• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2004년도 ISMP Pb-free solders and the PCB technologies related to Pb-free solders
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• pp.211-219
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• 2004

A new alloy definition will be presented concerning increasing demands for the board level reliability of miniaturized interconnections. The damage mechanism for LFBGA components on different board finishes is not quite understood. Further demands from mobile phones are the drop test, characterizing interface performance of different package constructions in relation to decreased pad constructions and therefore interfaces. The paper discusses the characterization of interfaces based on SnPb, SnPbXYZ, SnAgCu and SnAgCuInNd ball materials and SnAgCuInNd as solder paste, the stability after accelerated tests and the description of modified interfaces stric시y related to the assembly conditions, dissolution behavior of finishes on board side and the influence of intermetallic formation. The type of intermetallic as well as the quantity of intermetallics are observed, primaliry the hardness, E modules describing the ability of strain/stress compensation. First results of board level reliability are presented after TCT-40/+150. Improvement steps from the ball formulation will be discussed in conjunction to the implementation of lead free materials. In order to optimize ball materials for area array devices accelareted aging conditions like TCTs were used to analyze the board level reliability of different ball materials for BGA, LFBGA, CSP, Flip Chip. The paper outlines lead-free ball analysis in comparison to conventional solder balls for BGA and chip size packages. The important points of interest are the description of processability related to existing ball attach procedures, requirements of interconnection properties and the knowledge gained the board level reliability. Both are the primary acceptance criteria for implementation. Knowledge about melting characteristic, surface tension depend on temperature and organic vehicles, wetting behavior, electrical conductivity, thermal conductivity, specific heat, mechanical strength, creep and relaxation properties, interactions to preferred finishes (minor impurities), intermetallic growth, content of IMC, brittleness depend on solved elements/IMC, fatigue resistance, damage mechanism, affinity against oxygen, reduction potential, decontamination efforts, endo-/exothermic reactions, diffusion properties related to finishes or bare materials, isothermal fatigue, thermo-cyclic fatigue, corrosion properties, lifetime prediction based on board level results, compatibility with rework/repair solders, rework temperatures of modified solders (Impurities, change in the melting point or range), compatibility to components and laminates.

• 마이크로전자및패키징학회지
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• 제23권4호
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• pp.57-61
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• 2016

대용량 전력저장용 황화나트륨 기반의 전지를 개발함에 있어서 베타 알루미나 고체 전해질 튜브와 알파 알루미나 셀 캡 간의 물리적 접합을 위해서는 세라믹-세라믹 접합용 씰링 글라스 후막 페이스트가 필요하다. 본고에서는 글라스 프릿 분말의 입도, 열처리 조건이 씰링 글라스의 열처리 후 미세구조 특히 기공율과 그 분포에 미치는 영향을 연구하였다. 씰링 글라스 분말의 입자가 클수록 열처리 후의 글라스의 미세 조직상에서의 기공율 및 기공의 수가 감소하였으며, 열처리 온도가 증가 할수록 기공의 수가 감소하는 반면 기공의 크기는 증가함을 확인하였다. 이로써 글라스 씰란트의 제조에 있어서, 글라스 페이스트용 글라스 프릿 분말의 입자 크기와 씰링 열처리 온도의 적절한 선정에 의해 글라스 씰링부의 미세구조에서 기공율과 기공의 분포 및 기공의 수를 제어할 수 있음을 보여주었다.

• Journal of Plant Biotechnology
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• 제45권1호
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• pp.45-54
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• 2018

This research was conducted to study the gene expression of coffee (Coffea arabica L.) seedlings under salt stress condition. A solution of five percent ($2.3dS\;m^{-1}$) deep sea water was used for the salt treatment, and it was thereby compared to normal irrigation water ($0.2dS\;m^{-1}$) used for the control treatment. The mRNA was extracted from the leaves of the coffee seedlings for a comprehensive analysis. In this study, a total of 19,581 genes were identified and aligned to the reference sequences available in the coffee genome database. The gene ontology analysis was performed to estimate the number of genes associated with the identified biological processes, cellular components and molecular functions. Among the 19,581 genes, 7369 (37.64%) were associated with biological processes, 5909 (30.18%) with cellular components, and 5325 (27.19%) with molecular functions. The remaining 978 (4.99%) genes were therefore grouped as unclassified. A differential gene expression analysis was performed using the DESeq2 package to identify the genes that were differentially expressed between the treatments based on fold changes and p-values. Namely, a total of 611 differentially expressed genes were identified (treatment/control) in that case. Among these, 336 genes were up-regulated while 275 of the genes were down-regulated. Of the differentially expressed genes, 60 genes showed statistically significant (p < 0.05) expression, 44 of which were up-regulated and 16 which were down-regulated. We also identified 11 differentially expressed transcription factor genes, 6 of which were up-regulated and rest 5 genes were down-regulated. The data generated from this study will help in the continued interest and understanding of the responses of coffee seedlings genes associated with salinity stress, in particular. This study will also provide important resources for further functional genomics studies.

• Toxicological Research
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• 제31권1호
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• pp.41-48
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• 2015

Owing to the increase in price of cigarettes in Korea, herbal cigarettes have received increasing attention as a non-smoking aid; however, its safety has hardly been studied. We analyzed some of the toxic components in the mainstream smoke of herbal cigarettes, performed a mutagenicity test on smoke condensates for safety assessment, and compared the results with the corresponding values of a general cigarette with the same tar content. Herbal cigarette "A" was smoked using automatic smoking machine under ISO conditions in a manner similar to general cigarette "T". The tar content measured was higher than that inscribed on the outside of a package. The mainstream smoke of herbal cigarette "A" did not contain detectable levels of tobacco-specific nitrosamines and nicotine. Carbon monoxide and benzo(${\alpha}$)pyrene contents in herbal cigarette "A" were higher than those in the general cigarette "T". The phenolic contents such as hydroquinone, resorcinol, and catechol in herbal cigarette "A" were higher than those in the general cigarette "T", but cresol contents in herbal cigarette "A" were lower than those in the general cigarette "T". The content of aromatic amines such as 4-aminobiphenyl in herbal cigarette "A" was higher than that in the general cigarette "T"; however, this difference was not statistically significant. On the other hand, 1-aminonaphthalene, 2-aminonaphthalene, and 3-aminobiphenyl contents in herbal cigarette "A" were lower than those in the general cigarette "T". The smoke condensates of herbal cigarette "A" exhibited a higher mutagenic potential than the condensates from the general cigarette "T" at the same concentration. We concluded that the mainstream smoke of herbal cigarette contains some toxic components, the smoke condensates of herbal cigarettes are mutagenic similar to general cigarette because of combustion products, and that the evaluation of the chemical and biological safety of all types of herbal cigarettes available on the market.

• 한국병원경영학회지
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• 제7권1호
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• pp.1-18
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• 2002

Empowerment is a multifaceted concept which can be described somewhat differently. In general, it is defined as the motivational concept of autonomy and self-efficacy. Recently, this concept of empowerment is applied to improve organizational staff's job satisfaction and organizational commitment in many organizations. Empowerment in service organizations has certainly generated more publicity than any other organizations. The objective of this study is to measure the degree of hospital administrative staff's empowerment using Spreitzer(1995)'s empowerment theory, and also to analyze the relationship of empowerment and job satisfaction and organizational commitment. Spreitzer argues that the work empowerment is composed of 4 dimensions (meaning, competence, self-determination, and impact) and each dimension influences employee's job satisfaction, organizational commitment, and organizational performance in the end. In order to carry out this study, data were collected by self-administered Questionnaires from 181 hospital administrative staff at 3 university hospitals in Inchon and Kyunggi-Do. The response rate is 86%. The Collected data were analyzed with SPSS statistical package V10.0. The major findings of this study are as follows: First, the degree of hospital administrative staff's empowerment is a high level point at the 7 Likert Scale. Second, the reliability of 3 variables, empowerment, job satisfaction and organizational commitment, was statistically satisfied(Cronbach's alpha>0.80). Third, as a result of correlation analysis, four components of empowerment, job satisfaction and organizational commitment showed a positive relationship. Finally, multiple regression analysis was conducted to find the impact of empowerment on job satisfaction and organizational commitment. In the case of job satisfaction, the meaning and competence factors have a positive effect(P<0.05). And the case of organizational commitment, the meaning and impact components have a positive relation(p<0.05). These results showed that the workplace empowerment is significantly related to employee's job satisfaction and organizational commitment.

• 한국정보통신학회논문지
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• 제14권2호
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• pp.485-492
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• 2010

본 연구는 모바일 기기 상에서 애플리케이션 작성 시 GUI를 지원하는 윈도우 기반의 컴포넌트 패키지 소프트웨어 모듈인 WFC에서, 보다 다양한 콘텐츠의 표현과 조작을 지원하기 위한 포커싱 가능한 테이블 컴포넌트를 제안한다. 모바일 기기의 특성상 작은 디스플레이에서 테이블 특성을 가지는 콘텐츠의 표현은 쉽지 않다. 자바와 같은 관련 연구들에서 몇 가지 방법들이 제안되었으나, 이들은 모바일 기기의 특성을 고려하여 제안된 것들은 아니다. 본 연구에서는 모바일 기기의 디스플레이상에서 테이블 특성을 가지는 콘텐츠의 알맞은 출력을 지원하고, 사용자가 지정하는 콘텐츠에 포커싱 조작이 가능하게 함으로써, 일반적인 테이블에 비해 보다 폭넓은 표현을 제공하는 확장된 테이블 컴포넌트를 설계하고 구현한다. 또한, GUI 관점에서 성능 평가를 위해 제안된 컴포넌트와 자바 Swing의 JTable과의 비교를 제시한다.

• Elastomers and Composites
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• 제59권2호
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• pp.73-81
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• 2024

In the field of electronic components, the potting material, which is a part of the electronic circuit package, plays a significant role in protecting circuits from the external environment and reducing signal interference among electronic devices during operation. This significantly affects the reliability of the components. Therefore, the accurate prediction and assessment of the lifespan of a material are of paramount importance in the electronics industry. We conducted an accelerated thermal aging evaluation using the Arrhenius technique on elastic potting material developed in-house, focusing on its insulation, waterproofing, and contraction properties. Through a comprehensive analysis of these properties and their interrelations, we confirmed the primary factors influencing molding material failure, as increased hardness is related to aggregation, adhesion, and post-hardening or thermal-aging-induced contraction. Furthermore, when plotting failure times against temperature, we observed that the hardness, adhesive strength, and water absorption rate were the predominant factors up to 120 ℃. Beyond this temperature, the tensile properties were the primary contributing factors. In contrast, the dielectric constant and loss tangent, which are vital for reducing signal interference in electric devices, exhibited positive changes(decreases) with aging and could be excluded as failure factors. Our findings establish valuable correlations between physical properties and techniques for the accurate prediction of failure time, with broad implications for future product lifespans. This study is particularly advantageous for advancing elastic potting materials to satisfy the stringent requirements of reliable environments.

• 대한치과의사협회지
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• 제53권11호
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• pp.855-869
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• 2015

The purpose of this study was to evaluate the oral health promotion of the disabled persons by voluntary dental services in Ulsan Metropolitan City. Two dentists taken a calibration training for national oral health survey examined the oral health status of 473 disabled persons from two special schools for the disabled children and adolescents, a residential facility and a gymnasium for the disabled persons in 2009-2010. The surveyed disabled persons in the age range was from 7 to 74 years old. Voluntary dentists, oral hygienists and other civilian volunteers had supplied with the oral health care services to the disabled persons at dental clinics of special schools for the disabled children and adolescents, and a dental clinic supported from Nam-Gu Public Health Center in Ulsan Metropolitan City since 1997. The obtained data from these surveys were analyzed with the SPSS statistical package. Among subjects aged 12-14 years, subjects with decayed, missing and filled teeth (DMFT) in permanent dentition was 46.9%; subjects with untreated decayed teeth, 17.2%. The number of decayed, missing and filled teeth in permanent dentition was 1.36. The proportion of decayed components of DMFT score was 28.00%; proportion of missing components of DMFT score, 1.43%; proportion of filled components of DMFT score, 70.57%. The proportion of filled components of DMFT score among disabled persons of all age group in Ulsan were evaluated to be a similar level to non-disabled citizens in Ulsan from 2010 Korean National Survey. The oral health care programs for disabled persons by voluntary services of dental professionals and other civilians are evaluated to be effective for the oral health promotion of disabled persons in Ulsan.

• 한국산학기술학회논문지
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• 제13권1호
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• pp.169-177
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• 2012

본 연구는 치위생(학)과 학생들의 치과위생사 양성 교육과정 요소에 관한 인식을 조사하기 위해 2009년 4월부터 6월까지 치위생(학)과에 재학 중인 학생 934명을 대상으로 진행되었으며, PASW Statistics 18.0 프로그램을 이용하여 분석한 결과는 다음과 같다. 교육목표, 교육내용 선정, 평가에 있어 중부권이 가장 높게 수도권이 가장 낮게 나타났으며, 전문학사 학위과정이 학사학위 과정보다 높게 나타났다. 교육내용 조직은 중부권이 가장 높게 호남권이 가장 낮게 나타났으며, 학사학위 과정이 전문학사 학위과정보다 약간 높게 나타났다. 요소별로 살펴보면, 교육목표 요소는 직업교육, 도덕적 윤리적 요소에서 높게, 창의적 측면에서 낮게 나타났다. 교육내용선정 요소는 학습가능성에서 높게 내용의 타당성과 관련성에서 낮게 나타났다. 교육내용조직 요소는 계속성, 계열성, 통합성 순으로 나타났으며, 교육평가 요소는 학교평가 준거에서 높게, 국가시험 방법에서 가장 낮게 나타났다.

• KIEAE Journal
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• 제11권4호
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• pp.63-70
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• 2011

In respond to the global energy crisis and climate change, there have been many ongoing national efforts to develop a sustainable housing prototype followed by "2 million Green Home Project" in Korea. More than 50% of nation's population are currently living in apartment housing thus the country is seriously in need of developing green apartment prototype. In this research, we focused on energy-conservative green apartment design prototype that have both passive components and active systems explored in a systemic design approach. After selecting an existing basic apartment unit, we analyzed and compared statistical data with the simulated annual energy consumption to match these two data sets for validating simulation accuracy performed with TRNSYS package. We performed energy simulations with different passive design factors such as varied insulation thickness, window types and infiltration rates as well as the active design factors including boilers and lighting fixtures to analyze their impacts on the energy performance of the housing unit using TRNSYS software. As a result, we acquired significant energy reduction effect with explored design strategies but the life cycle cost analysis for the final design guidline would need to be performed. In this study, we focused on a systematic comparative energy analysis based on TRNSYS that can improve the design of a green apartment housing.