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RISS 인기검색어
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- 저자 : 이상의(S. E. Lee) (검색결과 106 건)
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[論文] 흡기 밸브 주위의 정상 상태 유동에 관한 실험적 연구
이상석(S.S.Lee),이석재(S.J.Lee),김응서(E.S.Kim) 한국자동차공학회 1991 오토저널 Vol.13 No.6
In order to investigate the characteristics of flow around the intake valve exit, discharge coefficient and the velocity near the valve exit in steady state were measured using X-type hotwire. Valve and valve seat insert used in experiment were constructed as the same shape of production engine and the flow characteristics at various flow rates and valve lifts were investigated.<br/> From the results of discharge coefficient measurements, it is observed that there exists a similarity between the flow characteristics around the production engine valve and the typical poppet valve. Measurement of the velocity at the valve exit shows that the normalized radial velocity distribution is independent of the flow rate. When the mass flow rate is small, the difference between the primary direction of flow and the valve angle is large, but the difference becomes smaller as the flow rate increases.
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이만호(M H Lee),이상종(S J Lee),김철우(C W kim),채종찬(J C Chae),박영철(Y C Park),정을순(E S Chung),김명숙(M.S. Kim) 대한소화기학회 1988 대한소화기학회지 Vol.20 No.2
N/A Barrett's esophagus is a condition in which the normal stratified squamous mucosa of the esophagus is replaced by columnar mucosa, and it may be suspected on abnormal findings of endoscopy and the diagnosis is usually proved by biopsy. We have observed 10 cases suspecting with Barrett's esophagus on the endoscopic findings. Only 5 cases of them, however, could be proved as columnar epithelium-linked esophagus with histological examination. We observed for clinical features regarding age, sex, symptorns, habits, locations, combined diseases, and combined laboratory abnormalities for them. No significant differences of clinical features except serum lipid levels were seen between both groups of Barretts esophagus and chronic esophagitis. 1) All 5 patients with columnar epithelium-linked esophagus was male, and age distribution was from 35 to 60 with mean age of 50. 2) Number of the patients who complained reflux symptoms was 2 out of 5 patients. 3) There were 2 heavy alcohol consumers, 1 coffee drinkers, and 2 heavy cigarette smokers. 4) Location of the lesion was seen on upper esophagus in 3 cases, and on lower esophagus in 2 cases. 5) As a combined diseases, 2 cases with duodenal ulcer, 2 cases with fatty liver, one case with hepatitis, and one patient with rectal polyp. 6) In all 5 patients, serum cholesterol, serum triglyceride level, or both were elevated.
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질소 이온주입법에 의한 BN 박막의 계면구조 개선 및 밀착력 향상
변응선(E. Byon),이성훈(S.H. Lee),이상로(S.R. Lee),이구현(K.H. Lee),한승희(S.H. Han),이응직(E.J. Lee),윤재홍(J.H. Youn) 한국진공학회(ASCT) 1999 Applied Science and Convergence Technology Vol.8 No.2
ME-ARE법에 의해 합성된 c-BN 박막의 초기성장층 및 이의 계면구조를 개선하고 밀착력을 향상시키고자 후처리로서 질소이온을 주입 (PSII-N^+)하였다. 이온 주입량이 c-BN 박막의 미세구조, 계면구조에 미치는 영향에 대하여 조사하였으며 이와 함께 박막의 경도 및 박리특성에 미치는 효과를 고찰하였다. 질소이온 주입시 약 5.0×10^(15)atoms/㎠ 이상의 주입량에서부터 IR스펙트럼의 변화가 보이기 시작하였으며 5.0×10^(16)atoms/㎠ 이상의 주입량 이상에서부터 급격한 c-BN→ h-BN 상전환이 일어났다. HRTEM관찰 결과, 이온주입에 의해, sp² 결합을 하고 있는 취약한 초기성장층의 결정구조 개선을 확인할 수 있었으며 이온주입된 박막의 경도 및 박리거동을 비교하여 이온주입 및 주입량에 따른 경도 및 박리 상관관계를 설명하였다. The post ion implantation has been applied to modify early-grown BN layer and improve the adhesion of the BN films. The effect of ion implantation doses on microstructure and interlayer was investigated by FTIR and HRTEM. And the hardness and delamination life time of N^+-implanted BN films were measured. With increasing the ion dose up to 5.0×10^(16)atoms/㎠, the change of IR spectrum is observed. At 5.0×10^(16) atoms/㎠, a drastic transition of cubic phase into hexagonal phase is detected. The change of microstructure of early-grown layers by ion implantation is confirmed using HRTEM. Both microhardness and delamination life time of BN films increase with ion dose. The modification model of early-grown BN layers is briefly discussed based on the displacement per atom and excess boron in the BN film induced by ion irradiation.
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비휘발성 기억소자를 위한 NO / N₂O 질화산화막과 재산화 질화산화막의 특성에 관한 연구
이상은(S. E. Lee),서춘원(C. W. Seo),서광열(K. Y. Seo) 한국진공학회(ASCT) 2001 Applied Science and Convergence Technology Vol.10 No.3
초박막 게이트 유전막 및 비휘발성 기억소자의 게이트 유전막으로 연구되고 있는 NO/N₂O 질화산화막 및 재산화 질화산화막의 특성을 D-SIMS(dynamic secondary ion mass spectrometry), ToF-SIMS(time-of-flight secondary ion mass spectrometry), XPS(x-ray photoelectron spectroscopy)으로 조사하였다. 시료는 초기산화막 공정후에 NO 및 N₂O 열처리를 수행하였으며, 다시 재산화공정을 통하여 질화산화막내 질소의 재분포를 형성토록 하였다. D-SIMS 분석결과 질소의 중심은 초기산화막 계면에 존재하며 열처리 공정에서 NO에 비해서 N₂O의 경우 질소의 분포는 넓게 나타났다. 질화산화막내 존재하는 질소의 상태를 조사하기 위하여 ToF-SIMS 및 XPS 분석을 수행한 결과 SiON, Si₂NO의 결합이 주도적이며 D-SIMS에서 조사된 질소의 중심은 SiON 결합에 기인한 것으로 예상된다. 재산화막/실리콘 계면근처에 존재하는 질소는 Si₂NO 결합형태로 나타나며 이는 ToF-SIMS로 얻은 SiN 및 Si₂NO 결합종의 분포와 일치하였다. The characteristics of NO/N₂O nitrided oxide and reoxidized nitrided oxide being studied as super thin gate oxide and gate dielectric layers of nonvolatile semiconductor memory(NVSM) was investigated by dynamic secondary ion mass spectrometry(D-SIMS), time-of-flight secondary ion mass spectrometry(ToF-SIMS), and x-ray photoelectron spectroscopy (XPS). The specimen was annealed in NO/N₂O ambient after initial oxide process. The result of D-SIMS exhibits that the center of nitrogen exists at the initial oxide interface and the distribution of nitrogen is wider in the annealing process with N₂O than with NO annealing process. For investigating the condition of nitrogen that exists within the nitrided oxide, ToF-SIMS and XPS analysis were carried out. It was shown that the center of nitrogen investigated by D-SIMS was expected the SiON chemical bonds. The nitrogen near the newly formed reoxide/silicon substrate interface was appeared as Si₂NO chemical bonds, and it is agreed with the distribution of SiN and Si₂NO species by ToF-SIMS.
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이상형,박진철,이언구,Lee, S.H.,Park, J.C.,Rhee, E.K. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.3
This study aims to present the fundamental strategies to improve the Indoor Air Quality (IAQ) in apartment buildings. To investigate the concentration of indoor air pollutants such as radon, formaldehyde, and VOCs, both the document survey and the field measurement were conducted. In addition, to identify the source of the air pollutants, the laboratory experiment was carried out for various building materials. Finally, the minimum period to be reserved befor3e building occupation to ensure healthy IAQ, which largely depends on the ventilation rates, was simulated using a simple compuer program. The results of this study can be summarized as follows: 1. In case of newly-constructed apartment houses, concentrations of formaldehyde, VOCs and radon were found to exceed the standard. Meanwhile, at existing apartment houses, concentrations of VOCs, particularly toluene and xylene, highly exceeded the standasrd level. Concentrations of formaldehyde and radon, however, had been lowered according to the duration of occupation. 2. The laboratory experiment of concentration of pollutants per square meter of building material surface area showed that radon gas was much emitted from the gypsumboard; formaldehyde from flooring and wallpaper; and VOCs from paints and kitchen furnishings. The emission rates of formaldehyde and VOCs were proportional to air temperature. 3. According to the simulation of the minimum period to be reserved before occupation, newly-constructed airtight houses required about 190-200 days, and naturally ventialted houses with fully-open-windows required about 20-45days, in order to keep the level of radon gas lower than standard. Therefore, with the current practice, the date of occupation should be delayed for about 15 days.
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이상흥,김성일,민병규,임종원,권용환,남은수,Lee, S.H.,Kim, S.I.,Min, B.G.,Lim, J.W.,Kwon, Y.H.,Nam, E.S. 한국전자통신연구원 2014 전자통신동향분석 Vol.29 No.6
GaN(Gallium Nitride)는 3.4eV의 넓은 에너지 갭으로 인하여 고전압에서 동작이 가능하고, 분극전하를 이용한 캐리어 농도가 높아 높은 전류밀도와 전력밀도를 얻을 수 있으며, 높은 전자 이동도와 포화 속도로부터 고속 동작이 가능하여 고주파 고출력 고효율 소형의 전력증폭기 소자의 재료로 적합하다. 본고에서는 민수 및 군수 겸용 Ku-대역 및 Ka-대역 GaN 고출력 전력증폭기(SSPA: Solid-State Power Amplifier)와 관련된 GaN 전력증폭 소자, GaN 전력증폭기 MMIC(Microwave Monolithic Integrated Circuit), 내부정합 패키지형 GaN 전력증폭기 및 GaN SSPA에 대하여, 국내외 특허 기술동향과 연구개발 기술동향을 중심으로 고찰하고자 한다. 국외의 GaN 고주파 고출력 전력증폭기 기술의 연구동향이나 특허동향을 심층분석하여 연구개발에 활용하고자 한다.
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