미숙아 망막증

劉英碩 藥業新聞社 1991 (月刊) 醫藥情報 Vol.1991 No.7

議會政治의 本質

劉榮奭 단국대학교 정치학회 1958 정치학논집 Vol.2 No.-

合理的 人事考課制度에 대한 硏究

瀏榮奭 경기대학교경영대학원 1996 最高經營者課程 經營硏究 Vol.13 No.-

전자상거래를 위한 대표 속성을 이용한 협력적 여과 방법

류영석,양성봉 연세대학교 산업기술연구소 2001 논문집 Vol.33 No.1

In electronic commerce, it is important for customers to find the best goods among large information overload, with saving time and effort. That is, if we can recommend the best goods accurately, we will give a great satisfaction to an individual customer. Collaborative filtering can solve these problems. It recommends items through building a user profile from preferences for each item itself, and comparing preferences with other users' preferences for the same item. But collaborative filtering does not use the attributes of items. Therefore, in this paper, we present a new collaborative fi1tering algorithm that uses the representative attributes for better prediction accuracy. In order to demonstrate the effectiveness of our use the concept of representative attributes outperforms other collaborative filtering methods with better prediction accuracy.

L-Methionine 에 의한 적출 대동맥 평활근의 수축력 변동

김진혁,신홍기,김기순,류영석 한양대학교 의과대학 1993 한양의대 학술지 Vol.13 No.1

L-Methionine, an essential amino acids has been known to methylate membrane phospholigids altering the function of membrane ionic channels as a result of increased membrane fluidity in the smooth muscle cells. Recently it was reported that L-methionine enhanced not only the contractile response of rat aorta to KCI but also the slow component of the contractile response of rat aortic strip to norepinephrine. The present study was performed to investigate direct effect of L-Methionine on the vascular tension in the isolated rabbit and rat aortas. The contraction was expressed as a percentage of contraction induced by 5×10 M norepinephrine. Only after denudation, L-methionine (3×10 M) provoked a contraction (81.3 16.8%) of the isolated rabbit aorta which was not maintained well. On the other hand, L-methionine (1×10 -5×10 M) produced a concentration-dependent increase in tension of the isolated rat aorta with an intact endothelium. Following denudation of the vascular preparation, the L-methionine-induced contractions were markedly augmented. The contractile responses of rat aortic preparations to 50mM L-methionine before and after denudation were 37.2 ±10.1% and 66.3±14.4%, respectively. Methylene blue also augmented L-methionine-induced contractions in the isolated rat aorta. No contractile response to L-methionine was observed during superfusion with Ca²-free Tyrode solution. In the vascular preparation pretreated with caffeine (2×10 M) and ryanodine (3×10 M), L-methionine-induced contractions were markedly but not completely abolished, suggesting that L-methionine mobilized Ca requred for contration from Ca -storage sites, Sα and Sβ as well. Indomethacin, as inhibitor of cycloozygenase (10 M) had no effect on the contractile reponses of rat aortic rings to L-methionine. The results suggest that L-methionine produces both endothelium-dependent relaxation and endothelim-independent contraction in the isolated rabbit and rat aortas.

압저항 방식의 μN급 MEMS 추력 측정 시스템 설계 및 성능 예측

류영석,이종광,Ryu, Youngsuk,Lee, Jongkwang 한국추진공학회 2018 한국추진공학회지 Vol.22 No.6

마이크로 추력기의 성능평가를 위해 MEMS 추력 측정 시스템을 설계하였으며, 시스템의 성능 예측에 관한 연구를 수행하였다. 추력 측정 시스템은 빔, 박막, 압저항 센서로 구성된다. 시스템의 안정성 검증과 빔의 응력 변화를 확인하고 압저항 센서의 크기 및 위치 선정을 위해 FEM 해석을 수행하였다. 재료의 허용응력과 최대응력을 비교하여 설계한 시스템들의 안정성을 검증할 수 있었다. 압저항 센서는 높은 게이지 계수를 확보하기 위해 빔의 길이의 20%로 설계 하였으며, 기준형상의 박막과 빔의 크기는 각각 $15mm{\times}15mm$, $500{\mu}m{\times}500{\mu}m$로 설계하였다. In this study, an MEMS thrust measurement system was designed and a study on the performance prediction of system was performed to evaluate the performance of micro thruster. Thrust measurement system consists of beam, membrane, and piezoresistive sensor. An FEM analysis was carried out to verify the stability of the system, confirm the stress variation at the beam, and position the piezoresistive sensor. The stability of the designed system was verified by comparing the yield strength of the material with the maximum stress. The piezoresistive sensor was designed to be 20% of the length of the beam to obtain a high gauge factor. The size of the membrane and the beam of the reference model were designed to be $15mm{\times}15mm$, and $500{\mu}m{\times}500{\mu}m$, respectively.

이주노동자 대상 한국어 교수요목 설계 방안 연구 -입국 예정 이주노동자의 한국어 학습을 위해서-

류영석 한국언어문화교육학회 2008 언어와 문화 Vol.4 No.3

This study aims to develop the Korean language education syllabus to fit the migrant workers’ personal characteristics and traits on the basis of their needs and to enhance the basic communicative competence in their daily lives in society and at work. The migrant workers experience various kinds of difficulties in their daily lives, both inside and outside the workplace. These problems are due mainly to the lack of communicative competence on their part. This insufficient communicative competence can be attributed to the type of Korean learning that does not get accomplished systematically and substantially in their own respective countries. That is, the Korean language education syllabus does not reflect their needs and is not implemented and harmonized with the real circumstances and situations which they need to face in Korea. The problem worsens because the Korean language education syllabus they had is taught by their teachers in an arbitrary manner. This research aims to show that first of all, a suitable Korean language education syllabus that reflects the migrant workers’ needs should be developed in order that the Korean language education will be able to effectively accomplish the specific purposes that will benefit the migrant workers. This type of syllabus that will reflect the migrant workers’ needs will result in giving the learners more control of the communication process and enhancing their learning efficiency. This study aims to develop the Korean language education syllabus to fit the migrant workers’ personal characteristics and traits on the basis of their needs and to enhance the basic communicative competence in their daily lives in society and at work. The migrant workers experience various kinds of difficulties in their daily lives, both inside and outside the workplace. These problems are due mainly to the lack of communicative competence on their part. This insufficient communicative competence can be attributed to the type of Korean learning that does not get accomplished systematically and substantially in their own respective countries. That is, the Korean language education syllabus does not reflect their needs and is not implemented and harmonized with the real circumstances and situations which they need to face in Korea. The problem worsens because the Korean language education syllabus they had is taught by their teachers in an arbitrary manner. This research aims to show that first of all, a suitable Korean language education syllabus that reflects the migrant workers’ needs should be developed in order that the Korean language education will be able to effectively accomplish the specific purposes that will benefit the migrant workers. This type of syllabus that will reflect the migrant workers’ needs will result in giving the learners more control of the communication process and enhancing their learning efficiency.

눈感染症의 유형과 감별·치료

劉英碩 藥業新聞社 1990 (月刊) 醫藥情報 Vol.1990 No.8

압저항 방식의 μN급 MEMS 추력 측정 시스템 설계 및 성능 예측

류영석,이종광 한국추진공학회 2018 한국추진공학회지 Vol.22 No.6

In this study, an MEMS thrust measurement system was designed and a study on the performance prediction of system was performed to evaluate the performance of micro thruster. Thrust measurement system consists of beam, membrane, and piezoresistive sensor. An FEM analysis was carried out to verify the stability of the system, confirm the stress variation at the beam, and position the piezoresistive sensor. The stability of the designed system was verified by comparing the yield strength of the material with the maximum stress. The piezoresistive sensor was designed to be 20% of the length of the beam to obtain a high gauge factor. The size of the membrane and the beam of the reference model were designed to be 15 mm × 15 mm, and 500 μm × 500 μm, respectively. 마이크로 추력기의 성능평가를 위해 MEMS 추력 측정 시스템을 설계하였으며, 시스템의 성능 예측에 관한 연구를 수행하였다. 추력 측정 시스템은 빔, 박막, 압저항 센서로 구성된다. 시스템의 안정성검증과 빔의 응력 변화를 확인하고 압저항 센서의 크기 및 위치 선정을 위해 FEM 해석을 수행하였다. 재료의 허용응력과 최대응력을 비교하여 설계한 시스템들의 안정성을 검증할 수 있었다. 압저항 센서는 높은 게이지 계수를 확보하기 위해 빔의 길이의 20%로 설계 하였으며, 기준형상의 박막과 빔의 크기는 각각 15 mm × 15 mm, 500 μm × 500 μm로 설계하였다.

네트워크 동적 참여 기반의 효율적인 피어 - 투 - 피어 웹 캐슁 모델

류영석(Young-Suk Ryu),양성봉(Sung-Bong Yang) 한국정보과학회 2005 정보과학회논문지 : 정보통신 Vol.32 No.6

P2P(peer-to-peer) 웹 캐슁 모델은 서버 쪽에 집중되는 트래픽을 완화시킴으로써 전통적인 웹 캐슁 모델을 보완할 수 있다는 측면에서 최근에 활발히 연구되어 왔다. P2P 웹 캐슁은 클라이언트들의 로컬 캐쉬를 활용하여 부가적인 인프라의 추가없이 캐쉬 공간이 확대되는 효과를 얻을 수 있지만, 각 클라이언트들은 독립된 피어로서의 자율성(autonomy)을 가지므로 이러한 자율성의 제한을 최소화해야한다. 본 논문에서는 피어의 자율적인 동적 참여와 로컬 캐슁 전략을 보장하여 시스템의 실행 가능성(feasibility)을 높인 환경에서 효율적인 디렉토리 기반 P2P 웹 캐슁 시스템을 제안하였다. 제안하는 P2P 웹 캐슁 시스템은 동적인 P2P 네트워크 상에서의 오브젝트의 lifetime을 예상하여 이를 이웃 선택(neighbor selection)과 저장 공간 관리(storage management)에 적용하였다. 시스템의 성능 평가를 위하여 클라이언트의 http 요청 로그 데이터셋을 이용하여 트레이스 기반(trace-driven) 시뮬레이션을 수행하였다. 시뮬레이션 결과를 통하여 제안하는 시스템이 기존의 시스템에 비하여 주어진 동일한 환경에서 더 높은 정확성과 더 적은 리디렉션 실패(redirection failure)를 가짐을 확인하였다. A peer-to-peer web caching has been studied recently as it can reduce the traffic converged on the server side and can support the traditional web caching model. Although the peer-to-peer web caching has the merit of having additional cache space from the local caches of peers without additional infrastructure, several constraints such as dynamic participation and local caching strategy caused by the autonomy of peers in peer-to-peer networks may limit the performance of the peer-to-peer web caching. To overcome these limitations, we propose an efficient directory-based peer-to-peer web caching system under dynamic participation of peers. In the proposed caching system, we present new peer selection and replica management schemes by introducing the concept of the object lifetime in P2P networks. We evaluate the effectiveness of the proposed system through trace-driven simulations with a web log dataset. Simulation results show that the proposed system has higher accuracy and fewer redirection failures than the conventional directory-based P2P web caching system in feasible peer-to-peer networks.