침전법에 의한 알루미나 분말제조 IV.ZrO₂의 분산에 의한 Al₂O₃/ZrO₂ 복합체의 제조 및 기계적 특성

홍기곤,이홍림,이형직,이호순 연세대학교 산업기술연구소 1992 논문집 Vol.24 No.2

In this study, a precipitation method, one of the most effective liquid phase reaction, was adopted in order to prepare high-tech Al₂O₃/ZrO₂ composite ceramics. Al₂(SO₄)₃·18H₂O, ZrOCl₂·8H₂O and YCl₃·6H₂O were used as starting materials and NH₄OH as a precipitation agent. Fine powders were prepared at optimum calcination condition. Sinterability of each fine powder and the effects of ZrO₂ on the grain size and mechanical properties of Al₂O₃ were investigated. The composition of Al₂O₃/ZrO₂ composites was fixed as Al₂O₃-15v/o ZrO₂(+3m/o Y₂O₃). The effect of MgO on the grain size of Al₂O₃ZrO₂ ceramics was also investigated.

반응소결 Sialon 및 Sialon 세라믹스의 제조와 재소결 특성

이홍림,이형직,이은복 연세대학교 산업기술연구소 1991 논문집 Vol.23 No.2

Sialon and Sialon-SiC ceramics were prepared by reaction sintering and post-sintering of powder mixture of Si, Al₂O₃, AIN, SiC, Y₂O₃. The powders were mixed to have the composition of Z=2. After nitridation, the specimens were post-sintered with powder bed. In the nitridation process Si was nitrided effectively by decreasing the amount of N2 below 1.0cc/sec. In the case of using passive powder bed, weight loss and β-Sialon were observed. On the contrary, when active powder beds were used, weight gain, β-Sialon and J-Sialon were observed. In active powder bed, higher strength and lower shrinkage were observed. Composition D, post-sintered in the SNSOC powder bed, has the largist strength of 332 MPa and the shrinkage of 6.2%.

하동카올린의 탄소환원법에 의한 질화거동

이형복,이홍림,이형직,임헌진 연세대학교 산업기술연구소 1985 논문집 Vol.17 No.2

Nitridation behavior of Hadong Pink Kaolin was studied over the temperature range of 1250-1350℃ in N₂-H₂atmosphere. Carbon was used as a reducing agent. Mullite, α-quartz, Si₂N₂O, X-phase, 15R-AIN, SiC and cristobalite were formed as intermediate products during reaction. But the final product was almost β-Sialon phase, when the reaction proceeded longer than 10hr at the C/H.K.(SiO₂) ratio larger than 3.

플라즈마 소결 PZT 세라믹스의 유전특성

이형직,송두규,권혁병,정해경,윤상옥,이형복,이홍림 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-

소결첨가제나 바인더를 넣지않고 만든 무첨가 PZT 분말 성형체를 플라즈마 소결-로 열처리 후의 미세조직의 변화, PbO의 거동 그리고 이에 따른 유전특성을 로소결한 경우와 비교하여 다음과 같은 결과를 얻었다. 플라즈마 소결-로 열처리로 만든 PZT 시편이 로 소결 시편과 비교하여 입성장이 크게 일어나지 않은 미세조직을 나타내었으며, 또한 균일한 Pb, Zr, Ti 성분분포를 보였다. 유전특성에 있어서는 1kHz에서 20%정도의 유전율의 향상을 얻을 수 있었으며 유전소실 또한 40%정도 낮출 수 있었다. 상기의 결과는 DC 플라즈마 소결법의 특징인 소결초기의 급속가열 효과와 PbO의 증발 억제 효과에 의한 것으로 고려된다. PZT powder compacts without additives and binder were processed by plasma sintering-furnace annealing. Microstructures, PbO behaviour and dielectric properties were investigated, and compared to the specimen obtained by furnace sintering. The specimen prepared by plasma sintering-furnace annealing showed more not only fine microstructures but also homogeneous pb, Zr, Ti composition distribution, and revealed 20% higher dielectric constant as well as 40% lower dielectric loss (measured at 1kHz). Above results might be considered to be caused by rapid heating effects, high temperature sintering effects and preventing effects of PbO evaporation characterized by dc plasma sintering.

이축시험법에 의한 알루미나 세라믹스의 열충격파괴거동

이중현,박성은,이형직,이홍림 연세대학교 산업기술연구소 2001 논문집 Vol.33 No.1

The flexure strength distribution was observed with ball-on-3 ball test after thermal shock in 25℃ distilled water. Commercial alumina specimen(AES-11) was used, and after thermal shock and flexure test crack distribution was observed by dye-penetration. Statistical method for failure probability and comparison of failure probability of ball-on-3 ball test with that of 3-point bending test were studied. The nearest crack distance from the center of the specimen and crack density were considered as the factors affecting ball-on-3 ball test strength, and the nearest crack distance from the center of the specimen had a stronger effect on the flexure strength than crack density.

Si₃N₄/SiC 복합체의 기계적 성질에 미치는 Y₂O₃-Al₂O₃계 소결조제의 영향

이홍림,서유석,이형직 연세대학교 산업기술연구소 1992 논문집 Vol.24 No.2

Si₃N₄/SiC composites were prepared by mixing Si₃N₄powder with SiC powders of 0, 10, 20, 30 vol%. To these composites were added the powders of Y₂O₃-Al₂O₃system as sintering aids. These samples were hot-pressed at 1850℃ for 60min under a pressure of 30 MPa in N₂. Some of the samples were annealed at 1400℃ for 4 hr under N₂ before the measurement of mechanical properties. β-Si₃N₄ phase is starting powder was all transformed to β-Sic phase remained unchanged. The fracture toughness of the composites increased more or less with the increase of SiC content. The room temperature strength decrease was observed around 10-30 vol% of SiC content. For the sample in which grain boundary crystallization occurred after annealing, fracture toughness increased while roon-temperature strength decreased.

침전법에 의한 알루미나 분말제조 Ⅲ. 소결체의 열적·기계적 특성

임헌진,이홍림,이형직,홍기곤 연세대학교 산업기술연구소 1992 논문집 Vol.24 No.1

A precipitation method was adopted in order to prepare high-tech Al₂O₃ceramics. Al₂(SO₄)₃·18H₂O was used as a starting materials and alumimum hydroxides were obtained by single precipitation method at the pH condition 7 and 11, using NH₄OH as a precipitation agent. Fine Al₂O₃powders were prepared at optimum calcination condition and were sintered at 1650℃ for 4 h in air. Microstructures and mechhanical properties of Al₂O₃ceramics were investigated. Doped MgO limited the grain growth of Al₂O₃and increased grain size homogeneity of Al₂O₃Flexural stregth values were 340∼430 MPa. Critical temperature difference?? was 175 K showing rapid strength degradation by thermal shock.

A genome-wide association study of a coronary artery disease risk variant.

Lee, Ji-Young,Lee, Bok-Soo,Shin, Dong-Jik,Woo Park, Kyung,Shin, Young-Ah,Joong Kim, Kwang,Heo, Lyong,Young Lee, Ji,Kyoung Kim, Yun,Jin Kim, Young,Bum Hong, Chang,Lee, Sang-Hak,Yoon, Dankyu,Jung Ku, Hy Springer-Verlag 2013 Journal of human genetics Vol.58 No.3

<P>Although over 30 common genetic susceptibility loci have been identified to be independently associated with coronary artery disease (CAD) risk through genome-wide association studies (GWAS), genetic risk variants reported to date explain only a small fraction of heritability. To identify novel susceptibility variants for CAD and confirm those previously identified in European population, GWAS and a replication study were performed in the Koreans and Japanese. In the discovery stage, we genotyped 2123 cases and 3591 controls with 521 786 SNPs using the Affymetrix SNP Array 6.0 chips in Korean. In the replication, direct genotyping was performed using 3052 cases and 4976 controls from the KItaNagoya Genome study of Japan with 14 selected SNPs. To maximize the coverage of the genome, imputation was performed based on 1000 Genome JPT+CHB and 5.1 million SNPs were retained. CAD association was replicated for three GWAS-identified loci (1p13.3/SORT1 (rs599839), 9p21.3/CDKN2A/2B (rs4977574), and 11q22.3/ PDGFD (rs974819)) in Koreans. From GWAS and a replication, SNP rs3782889 showed a strong association (combined P=3.95 10(-14)), although the association of SNP rs3782889 doesn't remain statistically significant after adjusting for SNP rs11066015 (proxy SNP with BRAP (r(2)=1)). But new possible CAD-associated variant was observed for rs9508025 (FLT1), even though its statistical significance did marginally reach at the genome-wide a significance level (combined P=6.07 10(-7)). This study shows that three CAD susceptibility loci, which were previously identified in European can be directly replicated in Koreans and also provides additional evidences implicating suggestive loci as risk variants for CAD in East Asian.</P>

A Study on Organizational/Program Effectiveness : Definition, Measurement, and Factors Affecting It

Lee, Hong Jik,Bae, Chunghyu 이화여자대학교 사회복지연구센터 2004 이화사회복지연구 Vol.5 No.-

Recently, the rapid growth of the human service sector in the U.S. generates the need to develop its quality and accountability to gain a limited fund. Hence, the issue of effectiveness is becoming increasingly important in human service sector. In response to this environment, this study aimed to clarify the definition of organizational/ program effectiveness, to investigate organizational/program effectiveness evaluation and measurement issues, and to identify important factors affecting organizational/program effectiveness. This study reviewed approximately forty cases of theoretical or empirical research on effectiveness in organizations, especially human service organizations and social welfare programs. This study also included a few studies in other fields such as business and public management are included as they are relevant to the discussion of organizational and program effectiveness in social service sector. Results of this study are the followings. First, many previous studies regarded program effectiveness as a sub-category of organizational effectiveness, and as a result, they distinguished between program effectiveness and organizational effectiveness as two different levels. Secondly, various measures were used to test the effectiveness of program or organization in the previous research, and it was proved indirectly that developing valid and reliable measures in human service field is a difficult task. Thirdly, although diverse factors were reported to determine the level of program/ organizational effectiveness, factors related to human resource were most frequently indicated as key factors among them. These results suggest that continuous research, competition, and communication among social work researchers and practitioners are needed to establish firm and universally accepted definitions and to develop valid and reliable methodologies to measure them. 1980년대 이래로 미국의 사회복지학계에서 '조직 및 프로그램 효과성'은 중요한 화두가 되어왔다. 이러한 효과성에 대한 관심은 정부의 복지지출 감소로 인해, 제한된 재원을 확보하는 일환으로 인간봉사 조직에게 요구되어지는 책무성과도 그 맥락을 같이 한다. 이러한 사회적 상황에서, 본 연구는 조직 및 프로그램의 효과성에 관한 주요 개념과 측정 방법, 그리고 효과성에 영향을 미치는 요인을 명확히 하고자, 미국의 인간봉사 조직의 효과성에 관한 40여개의 연구문헌을 고찰하였다. 또한, 본고는 연구의 목적을 위해 인간 봉사 조직체뿐 아니라 일반기업체와 기타 공공기관을 대상으로 한 효과성 연구들도 부수적으로 활용하였다. 본 연구의 결과를 정리하면, 첫째, 효과성의 개념에 있어서는 프로그램 효과성은 조직 효과성의 하위개념으로 이해되며, 서비스 성과와의 비교에 있어서, 성과는 프로그램의 결과와 영향력, 성취 등으로 표현되며, 효과성은 이러한 성과가 제시한 목표에 근접하는 정도로 제시되고 있다. 둘째, 효과성의 측정 방법에 있어서는 연구에 따라, 다양한 척도들이 이용되었는데, 이는 보편타당하고 신뢰할만한 척도의 개발이 용이하지 않다는 것을 간접적으로 증명한다. 셋째, 효과성에 영향을 주는 요인으로 다양한 요인들이 제시되고 있는데, 그 중에서 기관장의 가치, 지도력, 능력, 그리고 직원들의 인지능력과 행위 등과 같은 조직 구성원에 관련된 요인들이 주요한 효과성 결정요인으로 제시 되었다. 요컨대, 효과성에 대한 정의, 측정방법, 그리고 효과성 결정요인에 있어서, 연구의 목적 및 연구 대상 기관과 프로그램이 지향하는 목표 등에 따라 다양하게 규정되고 있음을 발견하였다. 결론적으로 본 논문은 사회복지학계에서 조직과 프로그램의 효과성에 대한 지속적인 연구와 논의를 통해, 보다 보편적으로 적용될 수 있는 개념의 정립 및 측정방법 상에서의 체계화가 필요함을 주장한다.

Early History of Korean Society

Lee Hong-jik The Academy of Korean Studies 1964 Korea Journal Vol.4 No.7