고효율 실리콘 태양전지를 위한 lotus surface 구조의 형성

정현철,백용균,김효한,음정현,최균,김형태,장효식,Jung, Hyun-Chul,Paek, Yeong-Kyeun,Kim, Hyo-Han,Eum, Jung-Hyun,Choi, Kyoon,Kim, Hyung-Tae,Chang, Hyo-Sik 한국결정성장학회 2010 韓國結晶成長學會誌 Vol.20 No.1

단결정 실리콘 태양전지의 광학적 손실을 감소시키는 표면 텍스쳐링은 최종 셀의 효율을 향상시키기 위하여 매우 중요하다. 본 연구에서는 2-step texturing의 공정으로 기존의 텍스쳐링에서 이루어진 피라미드에 수 많은 sub-micrometer 사이즈의 구조를 형성시켰다. $AgNO_3$ 용액으로 웨이퍼 표면에 Ag코팅을 한 후, 그 웨이퍼를 다시 HF/$H_2O_2$ 용액으로 수십초 동안 식각을 거치게 된다. 결과적으로, 피라미드 위에 생성된 수 nm사이즈의 구조물들은 $AgNO_3$의 농도 및 식각 시간의 변화에 의해 그 크기와 굵기가 변화하는 것을 알 수 있었다. 웨이퍼의 표면이 2-step texturing에 의해 식각이 이루어지면 연잎의 거친 표면과 비슷해지고, 그 결과 평균 10% 이상의 반사율을 보이던 기존 웨이퍼에서 3% 이하의 낮은 반사율을 얻을 수 있었다. 이는 일반적인 텍스쳐링과 anti-reflection coating을 거친 웨이퍼의 반사율보다 낮은 결과이다. The reduction of optical losses in mono-crystalline silicon solar cell by surface texturing is a critical step to improve the overall cell efficiency. In this study, we have changed the sub-micrometer structure on the micrometer pyramidal structure by 2-step texturing. The Ag particles were coated on the micrometer pyramid surface in $AgNO_3$ solution, and then the etching with hydrogen fluoride and hydrogen peroxide created even smaller nano-pyramids in these pyramids. As a result, we observed that the changes of size and thickness of nano structure on pyramidal surface were determined by $AgNO_3$ concentration and etching time. Using 2-step texturing, the surface of wafers is etched to resemble the rough surface of a lotus leaf. Lotus surface can reduce average reflectance from 10% to below 3%. This reflectance is less than conventional textured wafer including anti-reflection coating.

성견의 실험적 상피하 결합조직 이식시의 치주조직의 치유

정현철,최성호,조규성,채중규,김종관,Jung, Hyun-Chul,Choi, Seong-Ho,Cho, Kyoo-Sung,Chai, Jung-Kyi,Kim, Chong-Kwan 대한치주과학회 1997 Journal of Periodontal & Implant Science Vol.27 No.2

Several methods have been used for regeneration of tissue lost by periodontal disease. Subepithelial connective tissue graft technique, one of the technniques of mucogingival surgery, is used for the regeneration in esthetic problems such as recession, and denuded root coverage. This study is performed to evaluate the healing process and the regeneration and reattachment of periodontal tissue, including the reconstruction of junctional epithelium, and connective tissue. Alveolar defects in five adult dogs were treated with periodontal surgery and were attained by removing the marginal alveolar bone by $4{\time}3mm$ from CEJ in the labial side of incisors, and root surfaces were planed. The experimental sites were divided into two groups as follows. 1. root planing alone(control group) 2. with connective tissue graft (Experimental Group) In the two groups flaps were positioned and sutured tightly, the healing processes were observed and were histologically compared with each other after 2days, 4days, 1week, 2weeks, 4weeks. The results were obtained as follows : 1. In the two groups blood clots were observed as early as 2 and 4 days, and were resorbed at 1 week. 2. In the two groups moderate inflammation was observed as early as 2 and 4 days, decreased at 1 and 2 weeks, and disappeared at 4 weeks. 3. Junctional Epithelium migration was more significant in the control group, and was restrained by graft materials in the experimental group. 4. Features of connective tissue fiber attachment partially showed the parallel pattern in the two groups from 2 weeks, and entirely from 4weeks. 5. Anastomosis, between graft and connective tissue, appeared from 4 days in the experimental group and the border between them was not discriminated at 4weeks.

한의약의 변천과 갈등에 관한 연구

정현철,Jung, Hyun-Chul 대한한약협회 1998 大韓漢藥 Vol.2 No.-

시계열 프레임워크를 이용한 효율적인 클라우드서비스 품질·성능 관리 방법

정현철,서광규,Jung, Hyun Chul,Seo, Kwang-Kyu 한국반도체디스플레이기술학회 2021 반도체디스플레이기술학회지 Vol.20 No.2

Cloud service has the characteristic that it must be always available and that it must be able to respond immediately to user requests. This study suggests a method for constructing a proactive and autonomous quality and performance management system to meet these characteristics of cloud services. To this end, we identify quantitative measurement factors for cloud service quality and performance management, define a structure for applying a time series framework to cloud service application quality and performance management for proactive management, and then use big data and artificial intelligence for autonomous management. The flow of data processing and the configuration and flow of big data and artificial intelligence platforms were defined to combine intelligent technologies. In addition, the effectiveness was confirmed by applying it to the cloud service quality and performance management system through a case study. Using the methodology presented in this study, it is possible to improve the service management system that has been managed artificially and retrospectively through various convergence. However, since it requires the collection, processing, and processing of various types of data, it also has limitations in that data standardization must be prioritized in each technology and industry.

복부지방축적에 따른 남자 비만청소년의 골밀도,아디포사이토카인과 골대사지표의 관계

정현철 ( Hyun Chul Jung ),송종국 ( Jong Kook Song ) 한국스포츠정책과학원(구 한국스포츠개발원) 2014 체육과학연구 Vol.25 No.2

이 연구의 목적은 복부지방 축적에 따른 남자 비만청소년의 골밀도, 아디포사이토카인 및 골대사지표의 관계를 규명하는 것이다. 연구대상자는 12~14세 남자 청소년으로 총 24명(비만청소년:12명, 일반청소년:12명)이었다. 신장과 체중을 측정하였고, TW3 방법을 적용하여 뼈나이를 산출하였다. 신체구성과 골밀도 4부위는 DXA(Hologic, QDR- 4500W, USA)를 이용하여 분석하였다. 복부지방조직은 CT(ECLOS, Hitachi, Japan)를 이용하여 요추 4~5번 사이를 10 mm 간격으로 촬영하였으며, 총 복부지방조직(TAT), 내장지방조직(VAT), 피하지방조직(SAT), 그리고 내장지방 대 피하지방조직비(VSR)를 산출하였다. 아디포사이토카인으로 렙틴(leptin)과 아디포넥틴(adiponectin)을 분석하였고, 골대사지표는 골형성지표인 osteocalcin(OC)과 bone-specific alkaline phosphatase(BALP), 그리고 골흡수지표인 C-terminal telopeptide(CTx), N-terminal telopeptide(NTx)를 분석하였다. 복부지방 축적에 따른 그룹 간 차이를 규명하기 위하여 독립 t-검증을 적용하였고, 피어슨 상관관계수를 이용하여 종속변인들 간의 관계를 분석하였다. 또한, 다중회기분석을 통하여 복부지방조직과 골밀도의 관계를 분석하였다. 연구 결과 비만청소년은 일반청소년보다 지방조직(p<.001), 체지방률(p<.001), 총 복부지방조직(p<.001), 내장지방조직(p<.001)과 피하지방조직(p<.001)이 높게 나타났으나, 골무기질량(p<.01)은 일반청소년이 유의하게 높게 나타났다. 전신골밀도(p<.001)와 요추골밀도(p<.01)는 일반청소년이 비만청소년보다 유의하게 높게 나타났으나, 대퇴골밀도와 전완골밀도에서는 유의한 차이가 나타나지 않았다. 복부지방조직은 전신골밀도, 요추골밀도와 부적상관을 보였으며, 렙틴은 골밀도와 부적상관을 보인 반면, 아디포넥틴은 골밀도와 정적상관을 보였다. 골흡수지표인 NTx는 복부지방조직과 정적상관을 보였다. 또한 내장지방조직은 전신골밀도와 요추골밀도의 부정적인 예견인자로 나타났다. 결론적으로 남자 비만청소년은 일반청소년에 비해 낮은 전신골밀도와 요추골밀도를 보였으며, 총 복부지방조직, 내장지방조직, 및 피하지방조직과 부적상관을 보였다. 또한 렙틴과 아디포넥틴은 골밀도와 밀접한 관련이 있는 것으로 나타났으며, 내장지방조직은 청소년의 전신골밀도와 요추골밀도를 설명하는 부정적인 예견인자로 나타났다. 추후 연구에서는 비만청소년들의 복부지방축적의 패턴을 규명하고, 운동을 통한 복부지방조직과 골대사지표의 변화를 살펴보기 위한 후속연구가 필요할 것으로 사료된다. The purpose of the study was to determine relationship of abdominal fat, adipocytokine, bone mineral density, and bone turnover markers in obese male adolescents. Twenty four male adolescents (obese: 12, normal: 12) volunteered to participate in the study. Anthropometry and skeletal maturity were measured. Body composition and bone mineral density were estimated by DXA (Hologic, QDR-4500, USA). Abdominal fat with total adipose tissue (TAT), visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and visceral adipose tissue to subcutaneous adipose tissue ratio (VSR) were estimated by computed tomography (ECLOS, HITACH, Japan). Blood samples were obtained for and analysis of adipocytokines including leptin and adiponectin. Bone turnover markers, osteocalcin (OC), bone-specific alkaline phosphatase (BALP) for bone formation markers and N-terminal telopeptide (NTx), C-terminal telopeptide (CTx) for bone resorption markers were analysed. All data were analyzed utilizing SAS 9.3 (SAS Institute, NC, USA). Independent t-test was used to evaluate the differences between obese adolescents and normal adolescents. Pearson correlation analysis was applied to figure out the relationship between abdominal fat, adipocytokines, bone mineral density, and bone turnover markers. Multiple regression analysis was used to find out the factors of abdominal fat which influence on bone mineral density. A level of significance was set at p<.05. The results of the study indicated that fat tissue (p<.001), percent body fat (p<0.001), TAT (p<.001), VAT (p<.001), and SAT (p<0.001) were significantly higher in obese adolescents than normal adolescents. However bone mineral contents were significantly higher in normal adolescents. Normal adolescents have significantly higher whole body BMD and lumber BMD than obese adolescents. Abdominal fat including VAT and SAT related negatively with whole body BMD and lumbar BMD. Leptin related negatively with BMD whereas adiponectin related positively with BMD. NTx for bone resorption marker related positively with abdominal fat. Visceral adipose tissue was a predictor for whole body BMD and lumbar BMD in explaining 46% and 32% in adolescents. In conclusion, obese male adolescents have lower whole body BMD and lumbar BMD than normal adolescents. Abdominal fat including VAT and SAT related negatively with whole body BMD and Lumbar BMD. And leptin and adiponectin were closely related with BMD. Finally, visceral adipose tissue was a predictor for whole body and lumbar BMD in adolescents.

통신용 전원공급 신뢰성 증진을 위한 ISC-STS 제안

丁賢澈(Hyun-Chul Jung),玄東石(Dong-Seok Hyun) 전력전자학회 2008 전력전자학회 논문지 Vol.13 No.5

UPS의 신뢰성 향상을 위한 독립제어 고속절환장치

丁賢澈(Hyun-Chul Jung),玄東石(Dong-Seok Hyun) 전력전자학회 2008 전력전자학회 논문지 Vol.13 No.4

전단간섭법을 이용한 감육 곡관부의 변형 계측

정현철(Hyun-Chul Jung),김경석(Koung-Suk Kim),장호섭(Ho-Sub Chang),정성욱(Sung-Wook Jung),강기수(Ki-Soo Kang) 한국비파괴검사학회 2006 한국비파괴검사학회지 Vol.26 No.5

MIMO 시스템용 실시간 다중경로 페이딩 채널 시뮬레이터 구현

정현철(Hyun-Chul Jung),노유미(Yoo-Mi No),서석(Seok Seo),이찬길(Chan-Kil Lee) 한국통신학회 2004 한국통신학회 학술대회논문집 Vol.2004 No.11

IP 기반 이동통신망에서 개선된 형태의 IPv6 주소할당 메커니즘

정현철(Hyun-Chul Jung),이준원(Jun-Won Lee),민상원(Sang-Won Min),양승미(Seung-Mi Yang),이영로(Young-Ro Lee) 한국통신학회 2002 한국통신학회 학술대회논문집 Vol.2002 No.11