Droplet-Based Manufacturing 공정에 의해 제조된 무연 솔더볼의 제조공정 변수 연구

엄호천,조경목,송인혁,한유동 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.1

Uniform droplet of lead-free solder balls was produced by using the Droplet-Based Manufacturing(DBM) process. Compositions of solder were Sn, Sn-3.6 wt.% Ag, and Sn-3.8 wt.%Ag-0.6 wt.% Zn. Effect of parameters such as orifice size, pressure difference, and frequency on the solder ball production was also investigated. Mean size, size distribution, and surface defect of solder balls were analyzed with variations of the parameters. Droplet spacing decreased with increasing frequency and decreasing pressure difference. Thus the size of solder ball decreased with increasing frequency and decreasing pressure difference. Size distribution fell within the narrow range of ±5% from the mean diameter of solder balls. The experimentally measured diameter of the solder balls fabricated by DBM process coincided quite well with the theoretically anticipated value of d_d=A d_o^2/3.

연소반응 합성된 TiC 분말 소결체의 미세구조에 미치는 금속 Binder 영향

김명진,박민우,전재호,한유동 慶星大學校 1998 論文集 Vol.19 No.2

TiC cermets werefabricated by sintering of TiC and metal powders produced by self propagating high temperature systhesis (SHS). A total of five different cermet systems were studied. These are TiC-Ni, TiC-Co, TiC-Fe, TiC-Al and TiC-Cu. Powders of Ti, C, and metals (Ni, Co, Fe, Cu, Al) were first reacted to form TiC carbide in the matrix of each metal by SHS. The reaction products were crushed into fine powders, which were subsequently sintered at high temperatures either in hydrogen atmosphere or in vacuum for over 1 hours. The mocrosturctural evolution of the cermets was studied including carbide particle size and shape, growth of particles, and density of sintered body. The effects of different binder metals on the mocrosturctures of the cermets are discussed.

Creating Profits with Nonunion Workers: A Case Study of Market Basket

Yoo-Nah Hahn,Dong-Ho Kim 한국유통과학회 2015 Asian Journal of Business Environment (AJBE) Vol.5 No.1

Purpose - The study was designed to explore and examine the business relationships of the owners and the employees of Market Basket to analyze the implications of their recent turbulence and decisions. This article focused on two issues - business profit and labor union - to describe the uniqueness of this case. Design, methodology, data, and approach – This article, based on its purpose, applied all three approaches of case studies that are identified and described by Stake (1995), instrumental, intrinsic, and collective, to present the core nature of the issue and to improve and gain a clear understanding of this particular phenomenon. Results – The analysis of this case clearly indicates that seemingly dichotomous concepts of profit and employee welfare are not necessarily antithetical to each other Conclusions – The instant case of Market Basket serves as a testimonial for the rejection of the basic premises of corporate profits and labor unions. This case serves as a model and a practical example for many large retailers, especially the family operated retailers, and workers throughout the world.

R & D Status of Powder Metallurgy at the Center of Advanced Materials Processing(CAMP) in Korea

Hahn Yoo-Dong 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1

The 21st Century Frontier Program, which is one of the R&D programs funded by Korean government, was launched in 1999 to elevate the status of Korean science and engineering capabilities to the advanced nation in the strategic fields. Currently, 23 different fields of science and engineering programs are carried out by researchers in institutes, universities and industries. Center for Advanced Materials Processing (CAMP) was formulated in 2001 to develop the advanced materials as well as to improve the parts manufacturing process. The main role of CAMP is proposing and forecasting the long term vision in Materials Processing Technology and also supporting the project teams for their best performance in R&D. The CAMP program consists of 5 research areas such as, Multi-layer Ceramic Electronic Parts, Powder Formed Precision Parts, 3 Dimensional Polymer Based Composites, Functional Metal Sheets, Parts Integration Technology. An introduction of R & D activities at CAMP, specially focusing on powder metallurgy, will be presented.

Review of The Porous Materials

한유동 ( Yoo Dong Hahn ) 대한금속재료학회 ( 구 대한금속학회 ) 1994 분말야금 Vol.6 No.-

A Brief Analysis of Amazon and Distribution Strategy

Yoo-Nah Hahn,Dong-Ho Kim,윤명길 한국유통과학회 2018 유통과학연구 Vol.16 No.4

Purpose – The purpose of this paper is to analyze and illustrate Amazon’s business strategies and its success in terms of its distribution strategy and business practices. Research design, data, and methodology – This is an analytical case study that examines Amazon’s business strategies to demonstrate the importance of technologies to the success and sustainability of its organization. Results - The analysis indicates that the business strategies, including technology, distribution infrastructure, and customer service, are the most vital factor for the success and rise of Amazon, and these strategies have separated Amazon from its competitors in both e-tail and brick and mortar retail industries. Conclusions - Given Amazon’s continued growth that came with its constant strive for delivery and cost efficiency, technology innovation, and customer satisfaction, it was inevitable that Amazon would eventually venture into different types of businesses. The previous and current Amazon’s business strategies demonstrate that Amazon will continue to focus on developing and implementing new and creative strategies to separate itself from the rest of the retail and e-businesses. Furthermore, retail businesses in the most high-tech countries in the world, including Japan, Korea, and Russia, may have to adopt business strategies that are similar to those of Amazon to maintain their competitiveness.

Clinical Analysis of Cytomegalovorus Antigenemia After Allogeneic Bone Marrow Transplantation and a Suggestion of a Guideline to Initiation of Therapy

Yoo, Jin-Hong,Shin, Wan-Shik,Choi, Jung-Hyun,Kim, Dong-Wook,Lee, Jong-Wook,Hahn, Chi-Wha,Min, Woo-Sung,Kim, Chun-Choo,Kim, Dong-Jip 대한조혈모세포이식학회 1997 대한조혈모세포이식학회지 Vol.2 No.1

Objective: We retrospectively reviewed 56 cases of allogeneic bone marrow transplantation (BMT) recipients who were screened for the cytomegalovirus(CMV) infection by the antigenemia assay. The aims of this study were to analyze the incidence and the incidence and the clinical patterns of the CMV infection in BMT recipients and to suggest a guideline for therapy. Method: Retrospective analysis of 56 consecutive BMT recipients based on medical records from Mrach-1994 to August-1995. The antigenemia assay was done by using CMV-VUE kit(INCSTAR, USA). Manipulation of data was done by epilnfo 6.02(CDC, USA, 1994) Results: 1. The underlying diseases were acute lymphocytic leukemia(6), acute myelogenous leukemia(27), Chronic lymphocytic leukemia(13), and severe aplastic anemia(10). The male to female ratio was 27 to 29. 2. Thirty out of 56 patients(53.5%) were antigenemia positive and 10 patients were symptomatic. The mortality rate in antigenemia positive patients was 23.3%(7/30), while those without antigenemia was 7.7%(2/26). The range of detection-date was between the 30th-86th day and majority of cases were datected on the 30th day after BMT. 3. In patients with acute graft versus host disease, the risk of antigen positivity was high than in those without thus complication(Odd ratio 5.76, 95% confidence interval 1.53-22.73). 4. Among 14 patients who received gancicovir, 4 patients died(28.6%). In 16 patients who did not receive ganciclovir despite of antigenemia, 3 patients died(18.8%), but most of these patients showed low titer of antigenemia or asymptoatic. 5. Maximum number of antigen-positive cells and duration of antigenemia were the main influential factor for survival according to the covariate analysis. 6. When the number of antigen-positive cells was more than4/50,000 leukocytes, the mortality was highest. Hence, We recommend that antigen-positive cells ≥4/50.000 leukocytes could be the starting point of ganciclovir therapy. Conclusion: In our opinion, CMV antigenemia seems to affect the outcome of BMT recipients and more than 4/50,000 antigen-positive cells can be a acceptable guideline to initiate treatment in Korea.

An ankyrin repeat protein is involved in anthocyanin biosynthesis in <i>Arabidopsis</i>

Yoo, Jihye,Shin, Dong Ho,Cho, Man‐,Ho,Kim, Tae‐,Lim,Bhoo, Seong Hee,Hahn, Tae‐,Ryong Blackwell Publishing Ltd 2011 Physiologia Plantarum Vol.142 No.4

<P>The ankyrin domain is one of the most common protein motifs in eukaryotic proteins. Repeated ankyrin domains are ubiquitous and their mediation of protein–protein interactions is involved in a number of physiological and developmental responses such as the cell cycle, signal transduction and cell differentiation. A novel putative phytochrome‐interacting ankyrin repeat protein 2 (PIA2) containing three repeated ankyrin domains was identified in <I>Arabidopsis</I>. An in vitro pull‐down and phosphorylation assay revealed that PIA2 is phosphorylated and interacts directly with oat phytochrome A. The N‐terminal domain of PIA2 was specifically phosphorylated, whereas interactions between the domains of PIA2 and phytochrome A had no Pr/Pfr preference. PIA2 was ubiquitously expressed in most tissues and was localized in both the nucleus and the cytoplasm independent of treatment with light of specific wavelengths. Anthocyanin accumulation in seedlings grown under far‐red light, a typical phenotype of wild‐type plants, was reduced in a loss‐of‐function mutant of PIA2 (<I>pia2</I>), whereas anthocyanin accumulation was increased in an overexpressing plant (<I>PIA2‐OX</I>). The gene expression of UDP‐flavonoid‐3′‐glucosyl‐transferase (UF3GT), a major enzyme in the anthocyanin biosynthesis processes, was decreased in <I>pia2</I> knockout plants suggesting that decreased anthocyanin was because of the decreased expression of UF3GT. Our results suggest that PIA2 plays a role in the anthocyanin biosynthesis during seedling development as a novel phytochrome‐interacting protein.</P>

만성 임파성 백혈병1의 임상적 고찰

남동호,한지숙,민유흥,이선주,이종화,고윤웅 大韓血液學會 1991 大韓血液學會誌 Vol.26 No.2

급성백혈병에서 화학요법후 골수기능 회복시 말초혈액내 CD34⁺세포 출현에 관한 연구 -말초혈액 조혈모세포이식을 위한 예비연구 (I)-

민유홍,최동훈,이승태,남동기,이선주,한지숙,고윤웅 大韓血液學會 1993 大韓血液學會誌 Vol.28 No.1