열플라즈마를 이용한 탄화규소 분말의 합성

이시우,박혁상 한국화학공학회 1990 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.28 No.4

열플라즈마를 발생시켜 얻은 초고온 아르곤기체에 삼염화메틸사일린 [Si(CH₃)Cl₃]과 수소기체를 주입시켜 고온 화학반응에 의해 탄화규소 미세분말을 합성하였다. 이 때 최적 수소 농도는 3-4와 몰%로 나타났다. 이보다 적은 경우는 미반응 탄소분이 섞인 무정형의 탄화규소가 생성되는 것을 알았으며 큰경우는 미반응 규소가 생성됨을 알았다. 이 공정에서 얻은 분말은 20-60㎚의 크기를 가진 β-탄화규소로 나타났다. Ultrafine silicon carbide powders were chemically synthesized by introducing trichloromethyl silane and hydrogen into the high temperature thermal plasma argon gas. The optimum concentration of hydrogen was found to be about 3-4 mole%. Free carbon was included when the hydrogen concentration was lower than optimum and free silicon was formed when it was higher than optimum. It was also found out that powders synthesized were β-SiC with size distributions between 20 to 60㎚.

Dual Phase 전도성 CO₂ 분리막: 메커니즘, 미세구조 및 전기전도도

이시우,유지행,우상국,Lee, Shi-Woo,Yu, Ji-Haeng,Woo, Sang-Kuk 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.8

Novel conductive $CO_2$ membranes composed of dual phases, molten carbonates and electronic conducting ceramics, were investigated. As the microstructure control of electronic conducting ceramic supports is extremely important to keep the molten carbonates stable in the membranes by a capillary force applied by the pore structure of the supports, we have scrutinized the microstructure of the electronic conducting supports utilizing microscopic images and gas permeability measurement. From the evaluation of the electrical conductivities of the molten carbonates and the electronic conducting ceramic supports, we found that the ionic conductivity of the molten carbonates could determine $CO_2$ flux through the dual phase membranes if the surface exchange rate were relatively high enough.

手足汗症에 荊防地黃湯과 韓方 燻蒸方을 투약한 증례

이시우,박혜선,주종천,김경오 대한한방성인병학회 2000 韓方成人病學會誌 Vol.6 No.1

Though thoracic sympathectomy is widely used to treat essential hyperhidrosis or plantopalmar hyperhidrosis, many patients are not willing to be operated for its side effect such as compensatory hyperhidrosis, pneumothorax, Horner's syndrome, etc. A case of patient suggested palmoplantar hyperhidrosis who was recommended for sympathectomy from a university hospital showed favorable progress by Hyungbangjihwang-tang[荊防地黃湯] and herbal fumigation therapy.

솔 - 젤법에 의한 석영유리의 제조 : 2 . 초임계 건조 및 소결 2 . Supercritical Drying and Sintering

이시우,임재곤,고영표,이건홍 한국화학공학회 1993 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.31 No.1

2단계 sonogel공정에 의하여 제조된 젤을 초임계 건조하여 에어로젤을 만들고 이것을 소결하여 석영유리를 제조하였으며, 젤의 미세구조와 공정변수들 간의 상호관계들을 조사하였다. 초임계 건조의 용매로는 에탄올을 사용하였으며, 조업조건은 300℃, 1500 psi로 고정하였다. 소결은 150℃, 300℃, 400℃, 600℃, 900℃ 및 1100℃ 에서 등온을 유지하며 진행하였으며, 분위기 가스로는 질소(<300℃), 산소(300℃-600℃) 및 헬륨(>600℃)를 사용하였다. 초임계 건조에는 약 8시간, 소결에는 약 17시간이 소요되었다. 에탄올을 사용한 초임계 건조는 젤의 표면을 소수성으로 만들어 물의 흡착을 최소화함으로 소결에 유리하였다 너무 높은 초임계 건조온도는 입자의 수축을 가져와 오히려 소결에 불리하므로, 최적 초임계 건조온도가 존재하였다. 소결시 발생하는 부풀음을 방지하기 위해서는 150℃에서 수분을 충분히 제거해 주어야 하였다. 소결시 젤의 부피 변화는 1070℃까지는 완만하였으며,. 1100℃에서 급격히 기공이 닫히며 소결이 완결되었다. 초임계 건조가 불완전하거나, 낮은 pH에서 제조된 젤은 소결에 의하여 결정이 생기는 것을 관찰하였다. 초임계 건조를 채택한 경우에는 wet젤의 구조가 소결의 조건에 큰 영향을 주었다. Aerogels were manufactured by supercritical drying of the wet gel which was made using 2-step sonogel process and silica glass was obtained by sintering of these aerogels. Effect of the microstructure of aerogels on process variables was investigated. Ethanol was chosen as a supercritical drying solvent, and the operating condition was set to 300℃ and 1500 psi. Sintering was performed with isothermal stages at 150℃, 300℃, 400℃, 600℃, 900℃ and 1100℃, and gaseous atmosphere was changed from nitrogen(<300℃) to oxygen(300-600℃) and helium(>600℃). It took about 8 hours in supercritical drying, and 17 hours in sintering. Supercritical drying with ethanol made the surface of aerogels hydrophobic, resulting in minimum adsorption of water on the surface. Since reduction of particles occurred due to high temperature during supercritical drying, optimum supercritical drying temperature must exist. Long isothermal stage at 150℃ eliminated bloating of sintered sample. The volume of aerogels reduced slowly up to 1070℃, but the pores were closed suddenly at 1100℃. Incomplete supercritical drying and low gelation pH produced crystals in sintering. The structure of wet gel had strong effect on the sintering conditions.

제지애쉬를 혼입한 모르터의 특성에 관한 실험적 연구

이시우,Lee, Si-Woo 한국건축시공학회 2002 한국건축시공학회지 Vol.2 No.3

The purpose of this study is investigating characteristics of paper-ash mortar according to partial replacement of fine aggregate by Paper-ash. For this purpose, selected test variables were mixing ratio with two levels of mortar(1:2, 1:3), and 3 types of paper-ash(A, B, C), and paper-ash content with four levels(5%,, 10%, 15%, 20%). As a result of this study, in all mixes with partial replacement of fine aggregate by Paper-ash generally Produced Paper-ash mortar with decreased compressive strength at ail age as compared to ordinary mixes. The mixing rate 1:2 was the higher increasing rate of strength than the mixing rate 1:3. The flow value and unit weight of paper-ash mortar were decreased with increasing of the paper-ash content. And the thermal conductivity of the thermal conductivity of the paper-ash mortar was lower than normal mixing without paper-ash.

어레이 압저항 센서를 활용한 체질맥 임상연구

이시우,주종천,김경요,김종열,Lee, Si-Woo,Joo, Jong-Cheon,Kim, Kyung-Yo,Kim, Jong-Yeol 사상체질의학회 2006 사상체질의학회지 Vol.18 No.1

1. Objective Pulse diagnosis is generally applied to Traditional Oriental Medicine but not to Sasang Constitution diagnosis. Recently new pulse analyzer using array piezoresistive sensor and multi-channel robot arm developed. It reflects Oriental Medical Doctors' diagnostic processes, and its reproducibility test was done at Korea Institute of Oriental Medicine. We performed this study to set parameters diagnosing Sasang Constitution. 2. Methods One hundred thirty three subjects participated in this study. They are healty and approved this study. Before being tested with pulse analyzer, they had interview with Sasang Constitution Specialist to diagnose their Sasang Constitution. We established some useful parameters from parameters of pulse analyzer according to the Original Texts of Oriental Medicine and clinical experiences to analyze with clinical data of this study. 3. Results (I) There is a significant difference in pre-dicrotic notch time among all parameters of pulse analyzer in Sasang Constitution groups(P=0.047). (2) There is a significant difference in maximum pulse pressure in 33 to 48 year Sasang Constitution groups(P=0.010). (3) There is a significant difference in frequency width in 17 to 32 year Sasang Constitution groups(P=0.002). (4) There is a significant difference in CFS value in groups which OMD diagnoses; Floating & Sinking pulse(P=0.020). (5) There is a significant difference in pulse rate in groups which OMD diagnoses; Rapid & Slow pulse(P=0.000). (6) There is a significant difference in maximum pulse pressure in groups which OMD diagnoses; Deficient & Solid pulse(P=0.000). 4. Conclusions Analyzing parameters in each Sasang Constitution group, we found it shows significant difference in maximum pulse pressure and corresponding tendency in coefficient of floating & sinking pulse with theories of Sasang Consti-tutional Medicine. As we accumulate more clinical data, we will establish algorithm to diagnose Sasang Constitution using a pulse analyzer.

Locating Idle Vehicles in Tandem-Loop Automated Guided Vehicle Systems to Minimize the Maximum Response Time

이시우 대한산업공학회 2007 Industrial Engineeering & Management Systems Vol.6 No.2

An automated guided vehicle (AGV) system is a group of collaborating unmaned vehicles which iscomonly used for transporting materials within manufacturing, warehousing, or distribution systems. The performance of an AGV system depends on the dispatching rules used to assign vehicles to pickup requests, the vehicle routing protocols, and the home location of idle vehicles, which are called dwell points. In manufacturing handling are based on response times for pickup requests and equipment utilization. In an AGV system, the response time for a pickup request is the time that it takes for the vehicle to travel from its dwell point to the pickup station. In this article, an exact dynamic programming algorithm for selecting dwell points in a tandem-loop multiple-vehicle AGV system is presented. The objective of the model is to minimize the maximum response time for all pickup requests in a given shift. The recursive algorithm considers time restrictions on the availability of vehicles during the shift.

논 포장에서 해충 천적의 벼멸구 밀도 억제 효과

이시우,김승태,최병렬,이준호 한국응용곤충학회 2000 한국응용곤충학회 학술대회논문집 Vol.2000 No.1

유라시아 체계와 한반도

이시우 새얼문화재단 2010 황해문화 Vol.68 No.-

육성수조 내 북방전복, Haliotis discus hannai 치패 고밀도 중간양성 사육방식별 성장특성

이시우,김병학,박민우,김태익,손맹현 한국패류학회 2015 The Korean Journal of Malacology Vol.31 No.2

The effect of different intermediated rearing method by expanding the attached floor space in order to highly density culture on the growth characteristics and survival rate of the juvenile abalone, Haliotis discus hannai, were investigated in land-based tanks. The intermediated culture methods was determined thru the shelter counts and layer for 10 month with two replicates : the single layer shelter (SLS), the double layer shelter (DLS), the triple layer shelter (TLS) and the single layer shelter under net cage (SLSNC). In addition, the culture on shallow race way tank had to set up as culture of the ditch raceway tank (CDRT) and the floor race way tank (CFRT). In the growth performance of reared abalone (initial mean shell length 54.18 ± 7.39 mm and weight 1.93 ± 0.14 g) at experimental tanks, that the absolute growth rate (ARG), daily growth rate (DGR) and specific growth rate (SGR) to the shell length and shell breadth was not significant at each experimental tanks except SLSNC. As well as too, weight gain (WG), daily weight gain (DWG) and specific weight gain (SWG) to weight was not significant at each experimental tanks except SLSNC, too. Survival rates of CDRT and CFRT was lower than those of different experimental tanks (P < 0.05). Therefore, these results is showed that high density different intermediated rearing method by expanding the attached floor space for juvenile H. discus hannai was not have difference as growth performance and survival rate both one layer shelter and multi layer shelter. Also, it is considered that shallow race way tank was not useful rearing for the juvenile intermediate culture of H. discus hannai in land based.