• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.5
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• pp.615-627
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• 1997

An experiment was performed to local heat transfer coefficient and Nusselt number in the circular duct of 180.deg. bend for Re=6*10$^{4}$, 8*10$^{4}$ and 1*10$^{5}$ at swirling flow and non-swirling flow conditions. The test tube with circular section was made by stainless which has curvature ratio 9.4. The wall of test tube was heated directly by electrical power to 3.51 kw and swirling motion of air was produced by a tangential inlet to the pipe axis at the 180 degree. Measurements of local wall temperatures and bulk mean temperature of air are made at four circumferential positions in the 16 stations. The wall temperatures show particularly reduced distribution curve at bend for non-swirling flow but this effect does not appear for swirling flow. Nusselt number distributions for swirling flow which was calculated from the measured wall and bulk temperatures were higher than that of non-swirling flow. Average Nusselt number of swirling flow increased about 90 ~ 100% than that of non-swirling flow whole through the test tube. The Nu/N $u_{DB}$ values at the station of 90.deg. for non-swirling flow and swirling flow are respectively about 2.5 and 4.8 at Re=6*10$^{4}$. Also that is good agreement with Said's result for non-swirling flow. flow.

• KIEE International Transactions on Power Engineering
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• v.11A no.4
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• pp.45-50
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• 2001

The impact evaluation of a DSM program is a very important issue since the results are used to determine the sustainability of a program. In general. to estimate the impacts of a DSM program it is required to measure the electricity usage changes before and after a program. Since the measurement-based approaches cost highly, most of the conventional evaluations are based on the average figures. However estimation of the average-based impacts can lead to both distorted results of over/under estimation of kW and kWh savings and non-optimal DSM planning. In this paper, we have developed a new multi-point measurement approach which can evaluate kW and kWh savings of a DSM program more exactly. To do this, the saving rate and operating rate are defined and set as the function of load factor of a customer, and these rates are incorporated with the conventional diffusion function of Bass to project the future impacts of a DSM program. The case study is performed on the inverter program of Korea by using the suggested approach.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.1-9
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• 2000

To understand the thermal characteristics around the piston ring gap ring gap positions and piston temperatures are measured simultaneously. The locations of piston ring gap are measured by the radio-tracer method and piston temperature are measured by a K-type thermocouple and scissors type linkage system. From these experiments following facts are clarified. Piston temperatures fluctuate according to the piston ring rotation. And the temperature fluctuation is mainly affected by top ring gap position irrelevant to the second ring fop position. If the top ring gap position increases and the temperature of top ring groove shows maximum value when top rin gap position coincide with temperature measuring point. The maximum amplitude of temperature fluctuation which is proportional to the blow by gas rate is around 12-15$^{\circ}C$.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1359-1364
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• 2004

An experiment was performed to study the evaporation heat transfer and the pressure drop characteristics of liquid nitrogen in a horizontal stainless steel tube with wire coil inserts. The inner diameter of test tube is 4.3mm and the length is 1.5m. Four wire coils having different pitch and thickness were inserted into the plain test tube. The wire coil length is 1.5m and the diameter is 3.65mm with thickness of 0.5mm and 0.9mm. Experiments were conducted at saturation temperature of $-191^{\circ}C$ mass flux from 200 to 370 $kg/m^{2}s$ and heat flux of 62 $kW/m^{2}$. Direct heating method was used to apply heat to the test section. Boiling heat transfer coefficients of both the plain and the enhanced tubes were calculated. Pressure drops between inlet and outlet side of test section were also measured, and they are used to estimate EPR(Enhancement Performance Ratio).

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.4
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• pp.791-795
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• 2008

In the present study, Cordyceps sinensis extract (CSE) was evaluated to determine if it could protect pancreatic ${\beta}$ cells against cytokine-induced cytotoxicity of RINm5F cells. Treatment of cells with cytokines resulted in a decrease of viability, which was caused by increase of nitric oxide (NO) production. CSE protected cytokine-mediated viability reduction in a concentration-dependent manner. Incubation with CSE also induced a significant suppression of cytokine-induced inducible nitric oxide synthase (iNOS) protein and NO production. The molecular mechanism by which CSE inhibited iNOS protein expression appeared to involve the inhibition of $NF-{\kappa}B$ activation. The cytokine-stimulated RIN cells showed increases in $NF-{\kappa}B$ binding activity compared to unstimulated cells. However, pretreatment with CSE inhibited cytokines-induced $NF-{\kappa}B$ activation in RINm5F cells.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1177-1180
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• 2009

현재 국토해양부 4대강 홍수통제소에서는 369개의(2007년 한국수문조사연보 기준) 수위관측소를 설치 운영하고 있으며 현장에서 수집되는 수위자료의 측정방법은 부자식, 레이더식, 초음파식, 영상수위계 등 다양하다. 한강홍수통제소에서 자체 시험연구과제로 수행한 "TM 및 일반수위관측자료 비교분석연구" (국토 해양부, 2007)에 의하면 홍수예보를 위한 주요지점을 위주로 부자식과 레이더식, 부자식과 초음파식 등으로 수위계가 이중화 설치된 것으로 조사된 바 있다. 최근 홍수예보시 수위계 장비 자체의 결함이나 통신이상 등으로 발생되는 결측치나 이상치 자료를 최소화하기 위하여 주 관측방식이 부자식인 수위관측소에서 부자식 수위계의 기기 고장이나 부자 걸림 등이 발생되어 정상적인 자료 취득이 어려운 경우, 보조로 설치된 레이더식 또는 초음파식 수위계의 자료를 수신 받아 자료 손실을 최소화하고 주요지점의 자료 생산 제공 활용의 안정화를 도모하기 위함이다. 따라서 이러한 활용성을 극대화하기 위해 평상시 주 수위계와 보조 수위계에서 생산되는 자료를 동시에 저장하여 두 자료를 비교 분석하여 향후 홍수통제소에서 적용 가능한 자료관리 및 운영에 대한 개선방안을 제안하고자 한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1547_1548
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• 2009

제안된 Fabry-Perot Interferometer (FPI) 어레이 기반 IR 스펙트로미터는 상층부에 FPI 어레이와 하단에 $V_2O_5$ 볼로미터 IR 적외선 센서어레이로 크게 두 부분으로 구성된다. 이 구조에서 다양한 FPI 공진 캐비티의 두께에 의해 특정 공진 파장이 선택되어 진다. 그리고 각각의 볼로미터 IR 디텍터는 IR 파장에 상응하는 투과도를 감지해낸다. 다양한 박막 필터 시뮬레이션 결과를 통해 제작된 FPI 어레이 기반 IR 스펙트로미터는 $3{\sim}5{\mu}m$의 적외선 파장대역에서 흡수 스펙트럼을 가지는 $CH_4$, $CO_2$, $N_2O$, CO 가스 검출을 위해 다층 박막 FPI 층의 다층 박막 FPI 층의 투과율을 높였다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.446-451
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• 2011

Recent trends for the miniaturization and weight reduction of portable electronic parts have driven uses of subminiature components. Assembly of the miniaturized components requires subminiature screws of which pitch sizes are micrometer scale. To produce such subminiature screws with high precision threads, not only a precision forming technology but also a high-precision measurement technology is required. The present study covers the development of a vision inspection system for precision screws for the automatic measurement of subminiature screws with high speed and reliability. In this study, the feeding unit that transfers the subminiature screws to the inspection unit is investigated through finite element(FE) analysis. The vibration characteristics of the feeding unit are predicted through FE analyses, from which we can determine whether the subminiature screw can be stably fed into the inspection unit or not. The effects of several design parameters on the vibration characteristics are also discussed.

• The Transactions of the Korea Information Processing Society
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• v.6 no.4
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• pp.1045-1057
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• 1999

Packet-switched multistage interconnection networks(MINs) have been widely used for digital switching systems and super computers. In this paper we show that multiple packets in a switching element can move to the succeeding switching element in one network cycle by fully utilizing the cycle bandwidth. Only one packet movement was usually assumed in typical MINs. we present an analytical model for the MNs with the multiple packet movement scheme, and validate it by computer simulation. Comparisons with the traditional MINs of single packet movement reveal that the throughput is increased up to about 30% for practical size MINs. Similar result was also obtained for delays. The performance increase is more significant when the network traffic is nonuniform.

• Korean Journal of Veterinary Research
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• v.6 no.1
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• pp.37-41
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• 1966

Observations were made on the total serum protein values of 532 Korean cattles(341 females and 191 males and 191 males) and 90 milk cows in order to determine the effects of age, sex and nutritional status upon serum protein. Results obtained in this studies were summerized as follows; 1. The concentration of total serum protein was higher in the adult than in the younger and was generally increased with the advance of age in Korean cattle. The rate of increase in total serum protein content was more significant in the young than that of adult. 2. The average concentration of total serum protein of male did not differ significaltly from that of females in Korean cattle. 3. The concentration of total serum protein in milk cows were significaltly higher than that of Korean cattle cows and this difference seemed to be influenced by rations high in protein 4. A general tendency showed that the concentration of total serum protein was significaltly higher in the Korean cattle keeping with good nutritional status than that of poor nutritional status.