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Article
Publication date: 23 January 2025

Zhenxuan Zhang, Jaewoo Kim and Daehan Won

There are three major processes in the surface mounting technology (SMT) manufacturing line, namely, printing, mounting and reflowing. During the reflow process, the printed…

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Abstract

Purpose

There are three major processes in the surface mounting technology (SMT) manufacturing line, namely, printing, mounting and reflowing. During the reflow process, the printed solder pastes are melted into liquid and cooled down into solid again, forming the solder joint. During this process, because of the combined force of the liquid solder, the components will move from the placed location to the final location. This is known as the self-alignment performance in the reflow process. From the comparable studies, it is known that the reflow process with a longer time above the liquidus (TAL) results in better self-alignment performance, as well as higher peak temperatures of the reflow profiles. The TAL and the peak temperatures are influenced by multiple factors, but the experimental designs from the comparable studies kept the same ramping and cooling slopes to modify the TAL and the peak temperature. The purpose of this study is to study on the multiple factors influencing the TAL and the peak temperatures (ramping slope, cooling slope and peak temperature) by conducting designed experiments for each of the factors.

Design/methodology/approach

In this study, the TAL-influencing features are studied independently, including ramping slope, cooling slope and peak temperature; designed and conducted an experiment to reveal the relationship between the self-alignment and each of the three features; the statistical-based model for the combination of the three features for optimal self-alignment performance; and proposed a statistical-based simulation model for the offset after reflow.

Findings

The authors conducted a case study validating the mounter optimization model previously proposed. As a result, the optimized reflow profile improved the self-alignment performance by at least 10%, and the simulation within the error of 15 µm.

Research limitations/implications

This research is statistical-based, which is limited to component types and sizes used in the design of experiments (DOE). The model proposed in this study can suggest a new reflow profile that can increase the self-alignment performance, which is critical to the solder joint quality, especially long-term quality.

Practical implications

This study can suggest a new reflow profile that can increase the self-alignment performance, which is critical to the solder joint quality, especially long-term quality.

Social implications

This study can suggest a new reflow profile that can increase the self-alignment performance, which is critical to the solder joint quality, especially long-term quality.

Originality/value

The proposed statistical-based soldering reflow target profile optimization model offers a novel and practical approach. The soldering profile provided by the manufacturer contains recommended and acceptable ranges in the critical features. This study provides the optimal setting within the ranges.

Details

Soldering & Surface Mount Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 4 August 2021

Yuqiao Cen, Jingxi He and Daehan Won

This paper aims to study the component pick-and-place (P&P) defect patterns for different root causes based on automated optical inspection data and develop a root cause…

247

Abstract

Purpose

This paper aims to study the component pick-and-place (P&P) defect patterns for different root causes based on automated optical inspection data and develop a root cause identification model using machine learning.

Design/methodology/approach

This study conducts experiments to simulate the P&P machine errors including nozzle size and nozzle pick-up position. The component placement qualities with different errors are inspected. This study uses various machine learning methods to develop a root cause identification model based on the inspection result.

Findings

The experimental results revealed that the wrong nozzle size could increase the mean and the standard deviation of component placement offset and the probability of component drop during the transfer process. Moreover, nozzle pick-up position can affect the rotated component placement offset. These root causes of defects can be traced back using machine learning methods.

Practical implications

This study provides operators in surface mount technology assembly lines to understand the P&P machine error symptoms. The developed model can trace back the root causes of defects automatically in real line production.

Originality/value

The findings are expected to lead the regular preventive maintenance to data-driven predictive and reactive maintenance.

Details

Soldering & Surface Mount Technology, vol. 34 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 12 July 2022

Maitri Mistry, Rahul Gupta, Swati Jain, Jaiprakash V. Verma and Daehan Won

The purpose of this paper is to develop a machine learning model that predicts the component self-alignment offsets along the length and width of the component and in the angular…

249

Abstract

Purpose

The purpose of this paper is to develop a machine learning model that predicts the component self-alignment offsets along the length and width of the component and in the angular direction. To find the best performing model, various algorithms like random forest regressor (RFR), support vector regressor (SVR), neural networks (NN), gradient boost (GB) and K-nearest neighbors (KNN) were performed and analyzed. The models were implemented using input features, which can be categorized as solder paste volume, paste-pad offset, component-pad offset, angular offset and orientation.

Design/methodology/approach

Surface-mount technology (SMT) is the technology behind the production of printed circuit boards, which is used in several types of commercial equipment such as communication devices, home appliances, medical imaging systems and sensors. In SMT, components undergo movement known as self-alignment during the reflow process. Although self-alignment is used to decrease the misalignment, it may not work for smaller size chipsets. If the solder paste depositions are not well-aligned, the self-alignment might deteriorate the final alignment of the component.

Findings

It were trained on their targets. Results obtained by each method for each target variable were compared to find the algorithm that gives the best performance. It was found that RFR gives the best performance in case of predicting offsets along the length and width of the component, whereas SVR does so in case of predicting offsets in the angular direction. The scope of this study can be extended to developing this model further to predict defects that can occur during the reflow process. It could also be developed to be used for optimizing the placement process in SMT.

Originality/value

This paper proposes a predictive model that predicts the component self-alignment offsets along the length and width of component and in the angular direction. To find the best performing model, various algorithms like RFR, SVR, NN, GB and KNN were performed and analyzed for predicting the component self-alignment offsets. This helps to achieve the following research objectives: best machine learning model for prediction of component self-alignment offsets. This model can be used to optimize the mounting process in SMT, which reduces occurrences of defects and making the process more efficient.

Details

Soldering & Surface Mount Technology, vol. 35 no. 2
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 March 2010

Junsok Yang

The government procurement market is one of the few markets where substantial trade barriers still exist. Many countries, including Korea, have been trying to reduce these market…

134

Abstract

The government procurement market is one of the few markets where substantial trade barriers still exist. Many countries, including Korea, have been trying to reduce these market barriers through the World trade Organization (WTO) plurilateral government procurement agreement (GPA) and foreign trade agreement (FTA) negotiations. The actual results have been somewhat disappointing. This paper argues that one factor behind the disappointing results may be Korea’s negotiating text, heavily influenced by the GPA, that includes several provisions which may hinder efficiency and add to procurement costs. The paper offers a policy option for Korean FTA negotiators - a “half track” approach where Korea can offer mutual national treatment to the suppliers of the FTA partner with no (or very little) additional procedural or transparency requirements such as those associated with the GPA -type provisions.

Details

Journal of Public Procurement, vol. 10 no. 3
Type: Research Article
ISSN: 1535-0118

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Book part
Publication date: 10 November 2016

Eunha Koh

Although Korean sociology of sport is relatively unknown to the international community of scholars, it is a mature field in Korea. Sociology of sport was first introduced in…

Abstract

Although Korean sociology of sport is relatively unknown to the international community of scholars, it is a mature field in Korea. Sociology of sport was first introduced in Korea in the mid-1960s when the field first evolved in North America and Europe. However, the development of the field shows different aspects from its Western counterpart due to unique cultural and environmental factors both in academia and in society. There are three major research trends that form Korean sociology of sport. First, there is the research focus on the benefit of sport and physical activity by examining empirical data using quantitative methodologies. The second group of researchers pays attention to individual experience in diverse sport fields and utilize qualitative methodologies to investigate empirical or secondary data. The third and most recent trend is a critical approach that theoretically analyzes ideologies, power relations, and identity politics in sport and society. When looking at the future, there are problems and limitations within the field in Korea. These include lack of continuity in terms of conference sub-themes, over-production of doctoral degree graduates, conservatism rooted in the field, and a danger of regarding sport policy research as an exit for sport sociologists. However, there are also possibilities and reasons for optimism. The biggest possibility for Korean sociology of sport is globalization of the field. Another significant possibility is the need for sport sociologists in planning, developing, and evaluating sport policy. Finally, diversification of the field gives ample opportunities for future research.

Details

Sociology of Sport: A Global Subdiscipline in Review
Type: Book
ISBN: 978-1-78635-050-3

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Article
Publication date: 1 June 2003

You‐Il Lee and Michael Hobday

The Korean Government wishes to transform the nation into a Northeast Asian business hub. Following economic crisis, there are attempts to move the economy towards a new…

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Abstract

The Korean Government wishes to transform the nation into a Northeast Asian business hub. Following economic crisis, there are attempts to move the economy towards a new market‐oriented paradigm of economic growth based on foreign direct investment (FDI) and market friendly transparent corporate governance, replacing the old model of the developmental state, involving intimate and opaque business‐government relations, which has dominated Korean policy for at least three decades. This paper presents findings from 37 interviews conducted with senior executives of foreign companies and various chambers of commerce in Korea. The paper offers new insights into the critical and often invisible issues which need to be confronted and successfully resolved for the transformation of Korea. In providing a critical analysis, the paper examines alternative interpretations of the hub concept, key advantages offered by Korea, the main barriers to becoming a hub, competition from other locations and draws lessons for government policy makers.

Details

Management Decision, vol. 41 no. 5
Type: Research Article
ISSN: 0025-1747

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Book part
Publication date: 20 November 2020

Abstract

Details

Organized Labor and Civil Society for Multiculturalism: A Solidarity Success Story from South Korea
Type: Book
ISBN: 978-1-83982-388-6

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Article
Publication date: 1 August 1915

Before the appearance of our next issue, the Annual Meeting of the Library Association will have taken place. In many ways, as indicated last month, it will be an interesting…

23

Abstract

Before the appearance of our next issue, the Annual Meeting of the Library Association will have taken place. In many ways, as indicated last month, it will be an interesting meeting, largely because it is in the nature of an experiment. International conditions, the state of national and municipal finance, the absence of library workers with the colours, and the omission of social events, all tend to influence its character. It is possible, however, that these very circumstances may increase the interest in the actual conference business, especially as the programme bears largely upon the War. The programme itself is formidable, and it will be interesting to see how the section on the literature of the war, for example, will be treated. Probably the Publications' Committee have in mind the book symposia which are a feature of the meetings of various library associations in the United States. These consist of a few minutes' characterisation, by an opener, of a certain book or type of literature, and a discussion after it. The experiment was attempted in London last year at one of the monthly meetings, but owing to a misapprehension the speaker gave an excellent lecture on Francis Thompson of more than an hour's duration, when he had been expected to give a brief description of Francis Meynell's biography of that poet. If any gatherings for a similar purpose are arranged, we hope the speakers will be primed sufficiently to avoid that error. As for social events, their omission is less likely to be felt in London than anywhere else in the Kingdom. London is a perennial source of social amusement in itself, and the evenings can readily be filled there—“chacun à son goût”—really better than by attending pre‐arranged gatherings.

Details

New Library World, vol. 18 no. 2
Type: Research Article
ISSN: 0307-4803

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Book part
Publication date: 22 December 2005

Young-Myon Lee and Michael Byungnam Lee

While the origin of Korean Industrial Relations goes back 150 years when the country opened its seaports to foreign countries, it didn’t emerge as a field of study until 1950s…

Abstract

While the origin of Korean Industrial Relations goes back 150 years when the country opened its seaports to foreign countries, it didn’t emerge as a field of study until 1950s when academics began to write books and papers on the Korean labor movement, labor laws, and labor economics. In this paper, we sketch this history and describe important events and people that contributed to the development of industrial relations in Korea. Korean industrial relations in the early 20th century were significantly distorted by the 35-year-Japanese colonial rule (1910–1945). After regaining its independence, the U.S. backed, growth-oriented, military-based, authoritarian Korean government followed suit and consistently suppressed organized labor until 1987. Finally, the 1987 Great Labor Offensive allowed the labor movement to flourish in a democratized society. Three groups were especially influential in the field of industrial relations in the early 1960s: labor activists, religious leaders, and university faculty. Since then, numerous scholars have published books and papers on Korean industrial relations, whose perspectives, goals, and processes are still being debated and argued. The Korean Industrial Relations Association (KIRA) was formed on March 25, 1990 and many other academic and practitioner associations have also come into being since then. The future of industrial relations as a field of study in Korea does not seem bright, however. Issues regarding organized labor are losing attention because of a steadily shrinking unionization rate, changing societal attitude toward labor unions, and the enactment of new and improved laws and regulations regarding employment relationships more broadly. Thus, we suggest that emerging issues such as contingent workers, works councils and tripartite partnership, conflict management, and human rights will be addressed by the field of industrial relations in Korea only if this field breaks with its traditional focus on union and union–management relations.

Details

Advances in Industrial & Labor Relations
Type: Book
ISBN: 978-0-76231-265-8

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Article
Publication date: 4 November 2013

Hyun Jeong Min

During the 1920s and 1930s in the colonial city of Seoul, a group of women called the New Women and the Modern Girls expressed their modern identities by wearing different…

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Abstract

Purpose

During the 1920s and 1930s in the colonial city of Seoul, a group of women called the New Women and the Modern Girls expressed their modern identities by wearing different clothing, hairstyles and make-up; visiting cafés; viewing Western movies; and consuming other foreign merchandise. While these women were admired by many women as being pioneers of modernity, they were severely criticized by others under the pretext that they indulged their vanity without considering the economy of their families and their colonized nation. These criticisms continue in twenty-first century Korea. Based on the striking similarity between the two eras, an understanding of the consumption and the criticisms of the Modern Girls could provide a historical context for understanding women's experiences in the consumer culture of twenty-first century Korea. The paper aims to discuss these issues.

Design/methodology/approach

As secondary sources, literature published in both English and Korean was included. Primary data were obtained from articles in Korean newspapers, magazines and print advertisements from the 1920s and 1930s.

Findings

The New Women and Modern Girls expressed their modern identities by consuming various fashion goods, including Western-style clothes, make-up and various accessories, adopting Western hairstyles and frequenting modern cafés, theaters and department stores. However, their behaviors escaped the boundaries of the “wise mother, good wife” ideology, and they were severely criticized by those adhering to the neo-Confucianism and Korean nationalist ideology that was deeply rooted in Korean society. Thus, the reputations of the Modern Girls were tainted and the individuals were stigmatized.

Originality/value

This research illuminates the negative aspects of self-expressive consumption, showing how individualistic, identity-driven consumption can be stigmatized in the collectivistic culture of Korea that is rooted in neo-Confucian nationalism.

Details

Journal of Historical Research in Marketing, vol. 5 no. 4
Type: Research Article
ISSN: 1755-750X

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