• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.2
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• pp.238-246
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• 2004

This paper reports an experimental study around a module about forced air flow by blower (35${\times}$35${\times}$6㎣) in a portable personal computer model(200${\times}$235${\times}$10㎣). Experimental report is to know three data to investigate thermal resistance, adiabatic wall temperature and visualized fluid flow around the module by combination of the moving number and the arrangement method of blower. The channel inlet flow velocity has been varied between 0.26, 0.52 and 0.78㎧, and input power ( $Q_{p}$) to the module is 4W. To investigate thermal resistance. the heated module is mounted on two boards(110${\times}$110${\times}$1.2㎣, k=20.73, 0.494W/ $m^{\circ}C$) in parallel-plate channel to forced air flow. The temperature distribution were visualized by heated module on acrylic board(k=0.262W/ $m^{\circ}C$) using liquid crystal film. Fluid flow around the module were visualized using particle image velocimetry system.

• Korean Journal Plant Pathology
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• v.3 no.4
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• pp.285-290
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• 1987

Septoria brown spot caused by Septoria glycines Hemmi is one of the serious fungal diseases in soybean. Since little has been known about the disease progress in the field, the present study was conducted to determine the factors affecting the disease progress in the soybean plant. Disease severity and pattern of the progress of the Septoria brown spot were different with varieties. Susceptibility of soybean plants increased with increase of plant age and leaf maturity in order from the primary leaf to the newly expanded leaf. It seemed to be related with conidial germination on the leaves. Germination and germtube elongation were more inhibited by the diffusates obtained from upper leaves than those from lower leaves and they were higher in a susceptible variety than in a moderately resistant one.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.11
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• pp.17-22
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• 2000

A novel and robust direct parameter extraction method for hybrid-p equivalent circuit model of HBT is proposed. A new expression that can accurately resolve the base internal resistance from the measured S-parameters is derived, and it is not sensitive to the values of parasitic access inductance values. Based on the expression, six analytical expressions for the other parameters is developed and these expressions for hybrid-p equivalent circuit modeling ensure robust, fast, and reliable parameter extraction.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.43-49
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• 2008

Motivated by the Communication Broadcasting Convergence service, various technical approaches are being used to develop more efficient antenna models. This paper proposes a compact mobile antenna which is attachable to a cell phone and is applicable for Communication Broadcasting Convergence. In the design of the antennas for mobile handsets, size reduction is a crucial factor. In this paper, the compactness of a loop antenna is realized by bending a folded-dipole. A short planar dipole is transformed to a twice folded dipole and a loop antenna to produce a larger input resistance. The current distribution of the antenna is the same as a loop antenna, and its radiation patterns are omni-directional. We also analyze the performance of the RFID antenna by exploring the current-induced near field radiation patterns using a electro-optic field mapping system.

• Journal of IKEEE
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• v.4 no.2 s.7
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• pp.249-256
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• 2000

In EIT(electrical impedance tomography), the internal resistivity(or conductivity) distribution of the unknown object is estimated using the boundary voltage data induced by different current patterns using various reconstruction algorithms. In this paper, we present a regularized modified Newton-Raphson(mNR) scheme which employs additional a priori information in the cost functional as soft constraint and the weighting matrices in the cost functional are selected based on the exponentially weighted least square criterion. The computer simulation for the 32 channels synthetic data shows that the reconstruction performance of the proposed scheme is improved compared to that of the conventional regularized mNR at the expense of slightly increased computational burden.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.431-432
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• 2015

본 논문은 초고압 가스절연개폐장치의 메인 접점의 압점력에 따른 절연 특성에 대한 연구이다. 차단기 접점의 접촉이 잘 이루어지지 않는 현상이 발생하게 되면 접촉저항이 증가하여 차단기의 투입 및 개방 시에 전류에 의하여 접점에 손상이 발생한다. 그리고 차단기의 접점의 압점력이 커질수록 큰 조작력이 필요하므로 차단기의 동작에도 영향을 미치는 것은 많이 알려져 있다. 그러나 압점력과 절연 특성의 관계에 대한 연구가 미비하므로 이에 대한 연구가 필요하다. 본 연구는 초고압 가스절연개폐장치의 메인 접점의 압점력에 차이에 따른 전계를 해석하고, 고정측 접점의 쉴드 유무에 따른 절연 내력을 비교 및 분석하였다. 전계 해석 결과를 통해서 메인 접점의 압점력과 절연특성과 고정측 접점 쉴드의 영향을 비교함으로써 차단기 인터럽터 내부의 전계 분포를 확인하고, 전계 강도를 확인함으로 가스절연계폐장치의 적절한 절연내력 확보를 목적으로 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.2
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• pp.214-219
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• 2016

The grating is the main purpose of drainage in civil engineering, architecture. This study examined the change and stress distribution by simulating three models of Vertical type grating structures that reduced the resistibility in respect of velocity rather than horizontal type grating and to design a grating with the optimal grating gap. The vertical type and horizontal type grating were compared in terms of the maximum stress and strain to identify the better product.

• Korean Journal Plant Pathology
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• v.13 no.2
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• pp.118-124
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• 1997

The two viruses of barley yellow mosaic(BaYMV) and barley mild mosaic virus (BaMMV) were detected by ELISA from barley plants with virus-like symptoms which were collected from 16 locations in southern Korea, during 1995 and 1996. Both viruses occurred in southern Korea. Barley plants at Chongdo and Koseong were infected with BaMMV, while those infected with BaYMV were at Kurye and Taegu. After sowing 50 barley cultivars at habitually infected fields in 10 locations, the susceptibility and resistance to BaYMV and BaMMV were screened with antiserum tests. The cultivars of Albori, Alchanbori, Daejinbori, Jokangbori, Milyangbori, Boeunkwamek, Naehanssalbori, Olssalbori, Weossalbori, Dusan 29 and Deogndohyangchonkwa showed positive reaction to BaYMV antiserum, while Saeolbori, Chalbori, Jinjukwa and Baegjinkwa showed positive reaction to BaMMV. Nonsankwa 1-6 and wheat cultivars of Chongkeymil, Dahongmil, Grumil, Urimil, Jochonhomil, Sinkeyhomil showed negative reactions to both viruses. The rest cultivars were infected both with BaYMV and BaMMV. Sap inoculations to barleyplants with the two viruses of BaYMV isolated in Haenam and BaMMV isolated at National Honam Agricultural Station, expressed lower infection rate than those grown in the virus-infected fields.

• Korean Journal Plant Pathology
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• v.10 no.2
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• pp.92-98
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• 1994

Phytophthora infestans populations collected from various geographical locations of Korea in 1991 and 1993 were analyzed for mating types and responses to metalaxyl. Both A1 and A2 mating type isolates were detected in 1991. The majority of the isolates were A2 mating type, but no A1 mating type was detected in 1993. About 40% of the isolates collected in 1991 were resistant to metalaxyl, and the distribution of metalaxyl-resistant isolates of P. infestans was strongly associated with their geographic origins in Korea. Metalaxyl-resistant isolates with EC50 values > 50$\mu\textrm{g}$/ml were collected from the northern provinces of Kangwon, Kyungbuk, and Chonbuk, but not from the southern provinces of Kyungnam, Chonnam, and Jeju in 1991. The drastic increase in the degree of quantitative resistance to metalaxyl was detected among the isolates from the southern provinces during 1991~1993. More than 50% of the isolates collected from the southern provinces of Kyungnam and Chonnam in 1993 had EC50 values >50$\mu\textrm{g}$/ml. The province of Kangwon had isolates with the greatest resistance to metalaxyl. this alpine areas might be the origin of metalaxyl-resistant isolates of P. infestans in Korea. The A2 genotype with metalaxyl resistance appears to be displacing the A1 genotype which is presently the predominant genotype in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2891-2898
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• 2015

The new developed long distance transport technology uses the effect of electro-magnetic energy. But it's difficult to estimate the new technology. We monitored the velocity profile and pressure drops in pipes and estimated the technology quantitatively from data analysis. Laboratory test and field test gave us that the effects of electro-magnetic energy changed the flow properties and increased the velocity, especially at the slip layer. When transporting the dredged soil, electro-magnetic field generation reduces the frictional resistances at the slip layer, increases the velocity of flow. Furthermore, it would be possible to transport the dredged materials up to 15km long with one pump station.