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3차원 CFD 모형을 이용한 원형 교각의 국부세굴 특성 해석
오현식·김경호·양승룡 충북대학교 건설기술연구소 2008 충북대학교 건설기술연구소 논문집 Vol.27 No.1
Scour is a natural phenomenon, which occurs whenever a solid object is placed on loose sedimentary material, such as sand, in moving water. The flow of water is close to any such obstruction causes local increases in water velocity together with eddies and vortices. The flow phenomena are complex due to the presence of a boundary layer as well as and adverse pressure gradient set up by the bridge pier. Many researchers have conducted a vast number of experiments in laboratory flumes to investigate the local scour depth around a bridge pier. A few empirical formulas predicting the maximum scout depth have been developed under various experimental conditions. However, most of the experiments have been carried out in flumes under idealized conditions. such as steady flow, uniform sediment, simplified geometry, etc. The purpose of the study is to simulate accurately the flow field and scouring processes using a three-dimensional numerical flow model. In this study, for analyzing the mechanism of scouring process, CFD(computational fluid dynamics) model is used, based on the VOF(Volume of fluid) theory and finite differential equation. For the flow model, the simulated three-dimensional flatbed flow field(without bed slop) is compared with experimental data obtained by established scour equation and data. The results showed that 3D scouring flow field simulated by CFD model have almost the same phasis as experimental results.
이춘식,정병윤,하태명,박현건 진주산업대학교 농업기술연구소 2001 農業技術硏究所報 Vol.14 No.-
This study was carried out to investigate the purification effect of wastewater included LAS by electrolysis treatment system. Wastewater included LAS treated electrolysis treatment process, temperature of inner treated system were high than those of this raw wastewater, temperature change was electrolysis oxidation of LAS wastewater both cathode and anode. Electrolysis oxidation was oxidized LAS by oxidants of chlorine and ozone, on the time, according to the result development of treated efficiency on electrolysis contact time.
건축 단열재의 장기 경년변화에 따른 열전도율 변화에 관한 실험 연구 Ⅱ
최현중,정영선,김경우,강재식,이승언 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1
The objective of this study is to test for thermal conductivity of architecture insulation materials in domestic buildings with environmental condition change. In study, we measured change of thermal conductivity with test temperature change, long-time leaving and change of contained water rate. For long-time leaving test, the specimens of building insulation materials were kept in test conditions, which were influenced by the outside environment. The results of the study show 1) the contained water rate of artificial mineral fiber insulations was big for others, 2) thermal conductivity rose as test temperature(median) grew up and 3) the extruding insulations and hardened Urethane foam changed thermal conductivity with environmental condition and time elapse.
백서 뇌의 Ciliary Neurotrophic Factor 발현에 관한 면역조직화학적 연구
천현미,이영호,김원식 충남대학교 의과대학 지역사회의학연구소 1997 충남의대잡지 Vol.24 No.1
It was reported recently that ciliary neurotrophic factor (CNTF) is mainly present in the Schwann cells and asrocytes and maintain the motor neurons in postnatal periods. But there is no detailed research about the localization of CNTF. Several articles showed that there were many regions which have CNTF positive neurons. To test the unsettled CNTF immunoreactivity, the immunohistochemistry with CNTF antibody (Research & Development of the BML, Japan) was performed in th erat brain. The adult female rats weighing aound 200g were fixed by perfusion and 40-㎛-thick frozen sections were taken, and perform CNTF immunohistochemistry. The CNTF immunoreactivity was observed in the astrocytes of the optic nerve, olfactory nerve, fimbriae of the hippocampus, internal capsule, and cingulum, and in the non-astrocytes of the pyramidal tracts, the ventral portion of the pontine nucleus, and the central portion of the medulla oblongata. These data show that CNTF immunoreactivities present mainly in the astrocytes between the nerve fiber bundles in the cerebrum and in the non-astrocytes of the brain stem.
오현식,김경호 충북대학교 산업과학기술연구소 2002 산업과학기술연구 논문집 Vol.16 No.1
Submarine pipelines, one of the most important subjects in coastal engineering, are widely used in coastal structures. The stability of submarine pipelines is more important than other offshore structures, because local scour have influence on exposed pipelines due to waves generated in shallow water region. The local scour influence by wave should be previously considered because the self-burial caused to local scour induces additional static or dynamic loads and various risk elements. However, local scour occurring in waves has not been investigated as widely as in currents. This paper presents experimental investigations of scour depth with respect to scour parameters using regular waves. The investigations encompass shallow water region conditions. Developments of scour near the pipeline are observed and recorded due to variations of wave periods, wave heights and pipe diameters. This paper analyzes correlation between KC number and various scour parameters. By investigating new approach method suggested by C¸evik et al.(1999), it is found that modified Ursell number is valid for main parameters occurring to local scour below pipeline. Also this study analyzes relation between KC number and modified Ursell number and suggests modified equation based on experimental data. Under special experimental conditions, incomplete scours are appeared. This is caused by multiple correlation made with water depth(d), wave heights(H), period(T) and pipe diameter(D).
환경 및 시간경과에 따른 건축용 단열재의 열전도율 변화에 관한 실험적 연구
이승언,강재식,정영선,최현중 대한건축학회 2003 대한건축학회논문집 Vol.19 No.12
The objective of this research is to provide the basic experimental data for thermal insulation design standard of buildings and for test criterion. We tested the thermal conductivity of insulation materials which was the insulation materials in domestic buildings with environmental condition change and long-time elapse. In research, we measured change of thermal conductivity with change of contained water rate by weight, test temperature change and the passage of time. the specimens of insulation materials were kept in test condition, which was influenced by the outside environment during long-time elapse test. The result of the research shows 1)the contained water rate of artificial mineral fiber insulations is higher than others, 2)thermal conductivity rises as test temperature goes up, 3)the thermal conductivity of the extruding insulations and hardened Urethane foam changes with environmental condition and time elapse. As a result, the test methods and standards for thermal conductivity properties have much room for consideration.