메릴랜드주 교차로

정승현,이석홍,Jeong, Seung-Hyeon,Lee, Seok-Hong 한국도로학회 2001 도로포장공학회지 Vol.3 No.4

다중 주파수 발생기 설계를 위한 단일 인젝션 락킹 현상에 관한 연구

정승현(Seung-Hyeon Jeong),민경한(Kyeong-Han Min),이선규(Seon-Gyu Lee),정진원(Jin-Won Jeong),이승대(Seung-Dae Lee) 한국전자통신학회 2019 한국전자통신학회 논문지 Vol.14 No.6

본 논문에서는 다중 주파수 발생기의 설계를 위한 단일 인젝션 락킹 현상에 대한 연구를 진행한다. 다중 주파수 발생기 설계를 위하여 인젝션 락킹 현상에 대한 기본적인 이론을 서술하고 이를 토대로 단일 인젝션 락킹 실험에 대하여 서술한다. 실험은 인젝션 신호에 비해 불안정하게 진동하는 발진기에 일정하게 진동하는 안정된 신호인 인젝션 신호를 인가하는 방식으로 진행하였다. 인젝션 신호는 홀렌드 전류원을 사용하고 콜피츠 발진기를 사용하여 회로를 구성하였다. 실험결과 각각의 인젝션 신호(840kHz, 500kHz)를 주입하였을 때각각의 발진기가 안정하게 진동하는 것을 확인하였다. 위의 단일 인젝션 락킹 실험결과를 통하여 다중 주파수 발생기 설계에 인젝션 락킹 현상을 응용 할 수 있음을 확인하였다. This study describes injection locking phenomena for multi-frequency generator design. For the design of the multi-frequency generator, we describe the basic theory of injection locking phenomenon and conduct a single injection locking experiment based on it. The experiments was conducted by applying injection signals that vibrates consistently to oscillators which vibrates unstablely compared to injection signals. Injection signal was applied using a Howland current source and circuit was designed using a Colpitts oscillator. The results of the experiment showed that each oscillator oscillates reliable when injection signals(840kHz, 500kHz) are injected. Through the results of a single injection locking experiment, it is confirmed that injection locking phenomena can be applied in the design of the multi-frequency generator.

초고압 처리한 생굴의 압력별 탈각 성능과 관능적 특성 변화

정승현(Seung-Hyeon JEONG),민은비(Eun-Bi MIN),윤은아(Eun-A YOON),황두진(Doo-Jin HWANG) 전남대학교 어업기술연구소 2018 어업기술연구소보고지 Vol.11 No.1

We developed an automatic oyster separating machine using high hydrostatic pressure, and conducted research related to improving the working environment and increasing production volume. Changes in the by pressure cast off performance and sensual properties of raw oysters (Crassostrea gigas) treated with high hydrostatic pressure were evaluated. At a pressure of 175 MPa or more, the shell removal rate was over 90%. Samples automatically separated using high hydrostatic pressures of 250 MPa, 200 MPa, and 175 MPa together with a manually separated sample were evaluated using a seven-point rating scale for appearance (color, shape), smell, taste (salty, fishy), texture, and preference. The manually separated sample had similar rating values to the 175 MPa automatically separated sample. In conclusion, it is necessary to continue evaluation of the machine’s performance, sensory evaluation, oyster quality improvement oysters and development of technology for future commercialization.

空港立地選定에 있어서 GSIS의 活用에 關한 硏究

정승현(Jeong Seung Hyeon),임승현(Lim Seung Hyeon),김태근(Kim Tea Geun),조기성(Cho Gi Sung) 대한공간정보학회 1997 대한공간정보학회지 Vol.5 No.1

사회적 자본과 지식 창출이 공급사슬 성과에 미치는 영향

정승현 ( Seung Hyeon Jeong ),이창원 ( Chang Won Lee ) 한국생산성학회 2019 生産性論集 Vol.33 No.4

This study aims to investigate the effect of social capital and knowledge creation on supply chain performance in supply chain-based management environment. Since social capital has more important meaning than the study from the viewpoint of buyers who have conducted some studies from the viewpoint of suppliers. This study tried to prove how the role of structure of the supply chains is realized in the buyer-supplier relationship. The purpose of this study is to empirically analyze the effects of social capital and knowledge creation on supply chain performance in supply chain relationship. First, from the viewpoint of supplier, the influence of structural capital, cognitive capital, and relational capital on knowledge creation was identified. Second, the effect of knowledge creation on supply chain performance was demonstrated. Third, the mediating effect of knowledge creation was analyzed in the relationship between social capital and supply chain performance. For this purpose, a survey was conducted on employees who have worked for more than 5 years in the same sector in information and communication companies in Seoul and Gyeonggi Province. The measurement data were statistically analyzed through descriptive statistics, discriminant validity analysis, and confirmatory factor analysis, and the validity of the measurement items and the suitability of the measurement model were statistically analyzed. The research hypothesis was verified through the structural equation analysis on the research model. As a result of the analysis on demographic characteristics, the ratio of men was relatively high, with 101 men (53.7%) and 87 women (46.3%) in gender, and the distribution of age was 99 people (52.6%) under 30s, 65 people (34.6%) in 40s, and 24 people (12.7%) over 50s. The number of working years was 70 (37.2%) in 5-10 years, 47 (25.0%) in 10-15 years, 39 (20.7%) in 15-20 years, and 32 (17.0%) in 20 years or more. The largest number of companies were 101 companies (53.7%) with less than 100 employees, 51 companies (27.1%) with 100-500 employees, and 36 companies (19.1%) with more than 500 employees. The results of the analysis of the research hypothesis are as follows. First, social capital has a significant positive effect on knowledge creation. Second, knowledge creation had a significant positive effect on supply chain performance. Third, knowledge creation had a partial mediating effect on the relationship between social capital and supply chain performance. The implications of this study are as follows. First, companies should recognize the necessity of social capital and try to develop their capabilities to lead the competitive advantage that is specialized compared to competitors. Second, it is very important to establish, operate and manage more appropriate strategies in response to uncertain economic conditions. Third, the fact that knowledge creation has a significant mediating effect on the relationship between relational capital and supply chain performance explains the importance of social capital and the more important strategy among the factors affecting supply chain performance through knowledge creation. Although the effect of social capital and knowledge creation on supply chain performance was empirically verified in supply chain environment, the study results were not fully reviewed due to lack of previous studies. If these limitations are supplemented in the future, it is expected that sustainable and reasonable management plans will be devised in the uncertain management situation that is complicated and diverse enough to be unpredictable in the relationship between buyers and suppliers.

GSIS를 이용한 도로종합정보관리 시스템 구축

정승현(Jeong, Seung-Hyeon),임승현(Lim, Seoung-Hyeon),조기성(Cho, Gi-Sung) 한국측량학회 1998 한국측량학회지 Vol.16 No.2

매립 연령에 따른 침출수 특성

정승현 ( Jeong Seung Hyeon ),신현무 ( Sin Hyeon Mu ),정병곤 ( Jeong Byeong Gon ) 한국물환경학회 2003 한국물환경학회지 Vol.19 No.6

In order to investigate optimum process of leachate treatment depending on the landfill site age, anaerobic decomposition rate of organic matter and the change of ratio of humic and fulvic substances, distribution of organic matter after and before anaerobic degradation were studied. As the age of landfill site increases, it was observed that biodegradable organics were getting lower and the removal rate of dissolved organic carbon (DOC) under the anaerobic condition was decreased. It was found that over 50 % of the raw leachate was composed of high molecular weight organics (above M W. 10 K NMWL) and most of those were consisted of fulvic and humic acids. The older the landfill site is, the higher molecular weight of organic composition is. In the raw leachate. the fraction of fulvic was twice as much as that of humic acid. The removal efficiencies of fulvic and humic acids by anaerobic treatment were approximately 80 % and 20 %, respectively and which indicated that if humic acid were removed effectively, the leachate treatment efficiency could be improved.

무인항공기 기반 공간정보를 활용한 농작물보험 기초자료 수집기법 연구

정승현(Jeong, Seung Hyeon),최연웅(Choi, Yun Woong),조기성(Cho, Gi Sung) 대한공간정보학회 2018 대한공간정보학회지 Vol.26 No.3

공간정보는 스마트 사회로의 사회패러다임의 변화와 함께 인터넷 및 모바일 환경에서 위치정보를 기반으로 하는 다양한 분야에 활용되고 있으며 그 수요는 지속적으로 증가하고 있다. 한편, 농작물재해보험은 자연재해로 생산량이 감소하여 경제적 손실을 입은 농가의 손실을 보전하는 제도로써 매년 확대되어 적용되고 있다. 그런데, 농작물 보험의 가장 근본적인 기준이 되는 표준수확량 산정에 필요한 기초자료를 취득함에 있어 현지조사 방식에 조사결과의 객관성이 매우 낮은 상황이다. 따라서, 본 연구에서는 농작물재해보험을 운영함에 있어 반드시 필요한 기초자료조사 업무를 효과적으로 지원하기 위하여 무인항공기 기반의 공간정보를 구축하여 활용하는 방안을 제시하였다. Spatial information is being utilized in various fields based on location information in the internet and mobile environment, along with the change of social paradigm into a smart society, and the demand is continuously increasing. Meanwhile, crop insurance is a system to preserve the losses of farmers suffering from economic losses due to a decrease in production due to natural disasters. However, in order to obtain the basic data for calculating the standard yield, which is the most fundamental data of the crop insurance, it relies on the field survey method. Therefore, the objectivity of the survey results is very low. In this study, we propose a method to utilize spatial information based on UAV in order to effectively support the basic data investigation task which is essential in operating the crop insurance.

이형성 협심증의 임상상

강정아(Jeong A Kang),이유선(Yeu Seon Lee),정승현(Seung Hyeon Jeong),이정우(Jeong Woo Lee),김보영(Bo Yeong Kim),임대승(Dea Seung Im),이민수(Min Soo Lee),김정희(Jeong Hee Kim),정준용(Jun Young Jeong),최시완(Si Wan Choi),정진옥(Jin Ok J 대한내과학회 2002 대한내과학회지 Vol.63 No.2

목적: 우리나라는 이형성 협심증의 발생 빈도가 높음에도 불구하고 임상상과 예후에 대한 연구가 부족한 실정이다. 이에 본 조사는 이형성 협심증으로 진단을 받은 환자를 대상으로 그 빈도와 임상상 그리고 예후에 대해 연구 조사하였다. 방법: 1995년 1월부터 2000년 7월까지 흉통을 주소로 충남대학교병원 순환기 내과에 입원하여 관상동맥 조영술를 시행한 결과 관상동맥의 내경의 협착이 50% 미만이며 에르고노빈(ergonovine)8, 9) 유발 검사로 이형성 협심증으로 진단된 178명을 대상으로 하였다. 결과: 1) 관상동맥질환자 중 이형성 협심증 환자의 빈도는 13.2%로 높았다 2) 이형성 협심증의 위험인자는 흡연이 가장 많았다. 3) 이형성 협심증의 임상상은 대부분 불안정형 협심증의 양상이었고, 13.2%의 환자는 급성심근경색의 임상상을 보였다. 4) 흉통의 발생 시간대는 대부분 새벽이었고, 흉통의 지속시간 평균 11분으로 일반 협심증보다 길었다. 5) 흉통이 없을 때 검사한 심전도는 대부분에서 정상이었고, 운동부하 심전도검사는 76%에서 음성소견을 보였다. 6) 이형성 협심증의 진단에 에르고노빈 유발 관상동맥 조영술은 안전하고 유용한 검사이다. 7) 이형성 협심증의 치료에 칼슘길항제와 나이트레이트제제는 효과적인 약물이다. 8) 이형성 협심증의 예후는 비교적 양호하나 임의로 약물이 중단된 상태에서 심장사 할 수 있다. 따라서 이형성 협심증 환자는 흉통 발생에 대비한 나이트레이트의 준비가 필요하다. 결론: 본 조사에서는 관상동맥질환자의 13.2%가 이형성 협심증 환자였고, 이들은 약물 치료에 대한 효과와 예후가 비교적 양호하였다. 그러나 2.8%의 환자에서 심정지나 심장사가 발생하여 흉통 발생시에 적절한 나이트레이트제제의 사용이 필요하겠다. Background: Coronary artery spasm plays an important role in the pathogenesis of variant angina. However the precise mechanism (s) and the clinical characteristics of variant angina remain to be elucidated. We investigated the clinical characteristics and diagnostic features of variant angina. Methods: The clinical characteristics and coronary angiographic findings were analyzed in 178 patients with angiographically documented coronary artery spasm, which developed spontaneously or was provoked by the admistration of intravenous ergonovine maleate. All patients were followed for at least 1 year or more or until their death. Results: One hundred and eleven patients complained of chest pain which developed especially at night and in the early morning. One hundred and thirty three patients (74.7%) were smokers. The electrocardiographic findings at the time of admission showed no changes in 147 cases (82.6%), testes showed ST segment elevation in 22 cases (12.4%), ST segment depression in 2 cases (1.1%), T wave inversion in 7cases (3.9%). The treadmill test was performed in 135 cases, ST segment elevation was noted in 6 patients (4.4%) and ST segment depression in 18 patients (13.3%). All of the other results were within normal range. The ergonovine provovative tests for coronary spasms were safe and effective. The right coronary artery was the most prevalent site of coronary artery spasm. Drug treatment was applied initially to all patients, but only 115 patients (64.5%) received the follow-up. Of these three died from cardiac arrest. The rate of cardiac death was low (1.7%) in patient, which made it difficult to know the risk factors for the cardiac deaths. Two (1.1%) had cardiac arrest. They didn't take any medication. Patients with variant angina usually responded well to nitrates and calcium antagonists. Thus nitrates and calcium antagonists are useful in preventing attacks and abolished attacks of variant angina. Conclusion: In this study, 13.2% of coronary artery disease was variant angina. The effectiveness of drug therapy and the prognosis of the patients was quite good in the group. But when chest pain happens, the adequate use of nitrate agents is needed because of cardia arrest or cardiac death in 2.8% of the patients. (Korean J Med 63:195-202, 2002)

폐렴구균에 의한 지역사회 획득 폐렴에서 페니실린 내성률과 내성에 따른 임상경과에 관한 연구

홍지현 ( Hong Ji Hyeon ),이형석 ( Lee Hyeong Seog ),정승현 ( Jeong Seung Hyeon ),김규원 ( Kim Gyu Won ),엄광석 ( Eom Gwang Seog ),이재명 ( Lee Jae Myeong ),장승훈 ( Jang Seung Hun ),김동규 ( Kim Dong Gyu ),현인규 ( Hyeon In Gyu 대한결핵 및 호흡기학회 2003 Tuberculosis and Respiratory Diseases Vol.54 No.3