단단 축류압축기 유동해석에 대한 k-w 난류모델의 응용

이준석,김광용,Lee, Joon-Suk,Kim, Kwang-Yong 한국유체기계학회 2000 한국유체기계학회 논문집 Vol.3 No.3

A numerical study based on the three-dimensional thin-layer Navier-Stokes solver is carried out to analyze the flowfield through a single stage transonic compressor. Explicit fout-step Runge-Kutta scheme with spatially variable time step and implicit residual smoothing is used. The governing equations we discretized with explcit finite difference method. Mired-out average method is used at the interface between rotor and stator. And, an artificial dissipation model is used to assure the stability of solution. The results with k-w turbulence model were compared to the results with Baldwin-Lomax model, and physical phenomena of transonic compressor are presented. The two turbulence models give the results that show reasonably good agreements with experimental data.

한방병원에 내원한 위마비 및 비위마비성 기능성 소화불량증 환자에 대한 위 운동성 및 임상적 속성에 관한 연구

이준석,이선령,엄국현,김현경,장선영,유종민,김진성,류봉하,류기원,윤상협,Lee, Joon-Suk,Lee, Seon-Young,Eom, Guk-Hyeon,Kim, Hyun-Kyung,Jang, Sun-Young,Ryu, Jong-Min,Kim, Jin-Sung,Ryu, Bong-Ha,Ryu, Ki-Won,Yoon, Sang-Hyub 대한한방내과학회 2005 大韓韓方內科學會誌 Vol.26 No.4

Little is known concerning the pathophysiology and symptomatology of gastric dysmotility of patients who have sought treatment in eastern traditional medicine. The aim of this study was to investigate gastric electrical activity and clinical characteristics between gastroparesis and non-gastroparetic functional dyspepsia(FD) and assess the necessity to distinguish them for eastern traditional medical treatment. 60 patients were surveyed by questionnaire. Gastric electrical activity was recorded and analyzed using electrogas-trography. Patients were divided into gastroparesis and non-gastroparetic FD by 1.0 of power ratio. Healthy persons were used as reference. Postprandial normogastria of gastroparesis decreased and that of non-gastroparetic functional dyspepsia increased compared before and after meals. Suggested causes of onset were the meat diets that most patients were on in the gastroparesis group, and that drugs that patients in the non-gastroparetic FD group were taking. Distribution of main symptom was equally regular in patients with gastroparesis, but patients with non-gastroparetic FD showed mainly upper abdominal pain and fullness. Values for the gastroparesis group were double those for the non-gastroparesis FD group in frequency of upper GI endosopic examination. Results suggest that effective application of eastern traditional medical treatment requires that first a clear distinction be made in state of gastric dysmotility and clinical characteristics of gastroparesis and non-gastroparesis FD when treating dyspepsia.

흰쥐의 위(胃) 배출능(排出能)에 대한 반하사심탕(半夏瀉心湯)의 효능(效能)

이준석,김진성,류봉하,윤상협,Lee, Joon-Suk,Kim, Jin-Sung,Ryu, Bong-Ha,Yoon, Sang-Hyub 대한한방내과학회 2006 大韓韓方內科學會誌 Vol.27 No.2

Backgrounds & Objectives: Banhasasimtang granule(BHSST) has been used for the treatment of functional dyspepsia regarded as one of the gastric dysmotility disease. but its mechanisms of action are not well known yet: So we investigated the effects of BHSST on gastric emptying and its mechanisms of action in rats. Methods: Gastric emptying was measured by glass beads(1mm in diameter) expelled from the stomach for 60 min after administration of normal saline(NS) or BHSST 31mg/kg or 93mg/kg in rats. And by the same method gastric emptying was measured after administration of NS or BHSST 93mg/kg in rats treated with atropine sulfate(1mg/kg, s.c.), quinpirol HCI(0.3mg/kg, i.p.), NAME(NG-nitro-L-arginine methyl ester, 75mg/kg, s.c.) or cisplatin(10mg/kg, i.p.) to make delayed gastric emptying. Results: BHSST 93mg/kg improved gastric emptying more than NS or BHSST 31mg/kg(p=0.016). Under the delayed gastric emptying, BHSST 93mg/kg improved gastric emptying in the group treated with NAME$(5.00{\pm}3.101\;vs\;9.00{\pm}3.51,\;p\;=0.046)$, but aggravated it With atropine sulfate$(5.71{\pm}3.45\;vs\;2.57{\pm}1.62,\;p\;=0.050)$ and cisplatin$(12.7{\pm}2.29\;vs\;8.57{\pm}5.06,\;p\;=0.072)$. Conclusions: BHSST improves the gastric emptying through cholinergic and 5-hydroxytryptamine 3 receptors. Especially it is effective to improve gastric emptying delayed by NAME. So we expect that it would be effective in functional dyspepsia with impaired reservoir functions such as gastric adaptive relaxation.

현금흐름과 투자지출 관계의 산업별 분석

이준석(Lee, Joon-Suk),송준기(Song, Joon-Gi) 대한경영학회 2004 大韓經營學會誌 Vol.17 No.5

사용자 접근 특성을 이용한 새로운 포털 사이트 구조

이준석(Joon-Suk Lee),조용환(Yong-Hwan Cho) 한국엔터테인먼트산업학회 2008 한국엔터테인먼트산업학회논문지 Vol.2 No.2

본 연구에서는 기존 웹 포털 사이트의 콘텐츠 유용성, 페이지 디자인, 학습 용이성, 웹 기능성, 검색 정확도 등의 유용성 평가지표를 분석하여 그들 사이의 구조모형을 도출하였다. 이를 통해 요인들 간의 경로 관계나 구조적 모형이 각기 다른 웹 포털 사이트 간에 어떤 차이와 유사점을 보이는지 분석하고 이상적인 웹 포털 사이트의 구조 모델을 제안한다. 본 연구의 분석 결과를 요약하면 다음과 같다. 첫째, 웹 포털 사이트 간 판매되는 상품 콘텐츠에 따라 사용 연령층이 구분되어짐을 알 수 있다. 둘째, 특화된 주제를 서비스하는 포털 사이트의 구조와 다양한 콘텐츠를 서비스하는 포털 사이트의 구조적 차이점을 도출해 냈다. 마지막으로 각 표본이 되는 사이트에 대해 연구요인들의 관계를 분석하고 이상적인 구조모형을 도출한 후, 도출된 구조모형이 적용된 신생 웹 포털 서비스를 제안한다. In this paper, we deduce structure model between the facts such as usability index of Contents usability, Page design, Learnability, Web functionality, Seach accuracy, etc. of conventional web portal sites. According to this, we analyze similarity among the other web portal sites that has different path relation and structural model between the facts. The results of this research summarized as follows. First, the results show that user ages are differentiated by selling goods contents in web portal site. Second, we deduce structural difference of portal site that serve various contents and structure of portal site that serve specialized subject. Also we analyze relationships among research factors for sampled sites and deduce ideal structural model. Finally, we suggest new web portal service applied deduced structural model.

단단 축류압축기 유동해석에 대한 k-w 난류모델의 응용

이준석(Joon-Suk Lee),김광용(Kwang-Yong Kim) 한국유체기계학회 1999 유체기계 연구개발 발표회 논문집 Vol.- No.-

A numerical study based on the three-dimensional thin-layer Navier-Stokes solver is carried out to analyze the flowfield through a single stage transonic compressor. Explicit four-step Runge-Kutta scheme with spatially variable time step and implicit residual smoothing is used. The governing equations are discretized with explcit finite difference method. Mixed-out average method is used at the interface between rotor and stator. And, an artificial dissipation model is used to assure the stability of solution. The results with k-ω turbulence model were compared to the results with Baldwin-Lomax model, and physical phenomena of transonic compressor are presented. The two turbulence models give the results that show reasonably good agreements with experimental data.

Do Product Market Dynamics Influence Cash Holdings Behavior and Hedging Strategy of Korean Companies?

Lee, Joon-Suk(이준석),Sohn, Pan-Do(손판도) 한국산업경제학회 2015 산업경제연구 Vol.28 No.1

본 논문에서는 한국기업들의 현금보유 및 헤지 행동에 대한 상품시장 동태성의 영향을 실증분석하였다. 기존 연구에서는 성장기회를 가진 기업은 해당 라이벌기업에 대한 약탈행위를 유도할 수 있고 심지어 상품시장 점유율에 영향을 미친다는 증거를 제시하였다. 이러한 경우 라이벌기업과의 성장기회를 해당 기업이 공유할 경우 특히 나타난다는 것이다. 이러한 기존 연구결과를 기초로 한국기업들에서도 이러한 현상이 발생하는지 실증 분석 하였다. 즉 구체적으로 본 저자들은 라이벌 기업과의 경쟁에 직면하는 정도는 파생상품의 사용 및 현금보유규모에 영향을 주는지를 실증분석 한다. 실증분석 결과 한국 기업들은 위험관리 수단으로서 현금보유를 사용 할 가능성이 존재하였으며 이러한 결과는 기업 특성변수들을 통제한 후에도 동일한 결과를 보였다. 추가적으로 산업집중도가 높은 기업은 해당 라이벌 기업의 위협을 감소시키기 위하여 파생상품을 사용하는 경향이 있다는 증거가 발견되었다. This paper investigates whether there is an influence of product market dynamics on a Korean firm’s cash holdings and hedging behavior. Recent prior papers provide that taking advantage of growth opportunity forces to predatory behavior on rival firms and even losses in product market share if a firm shares a larger proportion of firm’s growth opportunities with its rival firms. This issue is closely related to predation risk. Specifically we examines whether the extent of competition in facing rival firms affects to its use of derivatives and the size of its cash holdings. In empirical test, we find that firms are likely to use cash holdings as a risk management tool after controlling characteristic variables of firms. Also our result shows that firms with more industry concentration tend to use derivatives to reduce risk of rival firm’s threat.

유비쿼터스 환경에 맞는 한국형 게임 플랫폼 연구

이준석(Joon-Suk Lee) 한국엔터테인먼트산업학회 2008 한국엔터테인먼트산업학회 학술대회 논문집 Vol.2 No.2

흡기 시스템이 공기유량계의 감지도에 미치는 영향에 관한 연구

이준석(joon Suk Lee),조영진(Youngjin Cho),박심수(Simsoo Park),한봉훈(Bong Hun Han) 한국자동차공학회 2002 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2002 No.5_1

The air fuel ratio of current gasoline engine is mostly controlled by a hot film type mass air flow sensor and manifold absolute pressure sensor. For precise measurement of intake air flow rate, sensor manufacturers request enough duct length nearly 10 times of a duct diameter making a fully developed flow. But, mass produced vehicles have no enough space to install such a lengthy intake system. Therefore, the inserted duct or bell mouthed duct was applied to confirm the stable fully developed intake flow in an air cleaner assembly. Various duct configurations before mass air flow sensor effect the precision of HFM's sensibility, due to air flow patterns are influenced by the geometry of intake system. This study mainly focused on the geometry of intake systems which influence on real air mass flow measurement of HFM. Test results could be used as the present on the guideline for designing of a intake system.

가상대학의 비용- 효과분석

이준석 ( Joon Suk Lee ),조정원 ( Jeong Weon Cho ) 한국교육공학회 1999 교육공학연구 Vol.15 No.3