• 전기학회논문지
• /
• 제60권3호
• /
• pp.465-470
• /
• 2011

Recently fault currents are increasing in a network. It is caused by increase in electric demand and high penetration of distributed generation with renewable energy sources. Moreover, distribution network has become more and more complex as mesh network to improve the distribution system reliability and increase the flexibility and agility of network operation. Accordingly, the fault current will exceed capacity of circuit breakers soon and all the various rational solutions to solve this problem are taken into account. Under these circumstances, superconducting fault current limiter(SFCL) is a new alternative in the viewpoint of technical and economic aspects. This study presents operation processes for a resistive-type of SFCL, and it proposes reliability model for the SFCL. When a SFCL is installed into a network, the contribution of decreased fault currents to failure for distribution equipments can be quantified. As a result, it is expected that a SFCL makes the reliability of adjacent equipments on existing network improve and these changes are analyzed. We propose a methodology to evaluate the reliability in the distribution network where a SFCL is installed considering a reliability model for resistive-type of SFCL and reliability changes for adjacent equipments which are proposed in this paper.

• 한국ITS학회 논문지
• /
• 제21권4호
• /
• pp.157-166
• /
• 2022

IoT 기술 중에서 가장 많이 쓰이는 무선 통신 기술에는 ZigBee, WiFi, Bluetooth, Z-Wave 등이 있다. 그 중에서 Z-Wave는 현재 세계 시장 점유율이 60%로 선호하는 기술 중 하나이다. 본 논문에서는 Z-Wave 프로토콜을 이용한 온습도 센서 모듈을 구현하였다. 온습도 센서 모듈의 동작을 위하여 Z-Wave 프로토콜을 분석하고, 컨트롤러 모듈의 펌웨어를 탑재하여 구현하였고, 센서 모듈은 데이터 시트를 참고하여 설계 및 제작하였다. 또한 센서의 온습도 정보를 모니터링하는 프로그램을 개발하여 이를 확인하였으며, Z-Wave 모듈의 통달거리 시험, 수신데이터 성공률, 저전력 시험 등을 통하여 성능을 확인하였다.

• 대한조선학회논문집
• /
• 제60권5호
• /
• pp.296-304
• /
• 2023

Cavitation tests for a waterjet propulsor of an amphibious vehicle are carried out in the Large Cavitation Tunnel. Waterjet pump performances and cavitation characteristics including thrust breakdown performances are investigated in the tests. In addition, cavitation characteristics for waterjet propulsors working inside the intake are calculated by using a commercial CFD code, Star-CCM+. Sliding mesh is implemented to a rotating impeller and the k-epsilon turbulence model is chosen. Cavitation bubble growth and collapse are estimated using the Schnerr-Sauer cavitation model based on Rayleigh-Plasset equation. Calculated results agree fairly well with experimental results. The re-design of the waterjet propulsor is performed to enhance waterjet cavitating performances and calculated results show that waterjet thrust breakdown characteristics are significantly improved.

• 한국식품영양과학회지
• /
• 제35권6호
• /
• pp.734-737
• /
• 2006

다양한 생리활성을 함유한 보리잎을 이용하여 관능적으로 우수한 보리잎 분말차를 제조하는 방법을 개발하고 분말차의 기능성 성분함량을 분석하였다. 다양한 실험조건으로 보리잎차를 제조한 후 관능적으로 우수한 제조조건을 선발하였다. 그 결과 보리잎 분말차를 제조하는 공정은 보리잎을 절단, 세척하는 전처리 공정, $100^{\circ}C$에서 30초간 가열하는 증열공정, $130^{\circ}C$에서 40분간 처리하는 조유공정, 실온에서 25분간 처리하는 유념공정, $60^{\circ}C$로 30분간 덖음하는 중유공정, $55^{\circ}C$에서 25분간 재덖음하는 정유공정, $60^{\circ}C$로 20분간 건조하는 건조공정, $85^{\circ}C$에서 20분간 회전 덖음하는 가향공정 및 분쇄공정으로 최적화되었다. 이상의 방법으로 제조된 보리잎 분말차는 식이섬유 33.8%, 아미노산 12.9%, 무기질 4.7%, ${\beta}-carotene$ 6.9 mg% 등이 함유되어 있었다.

• 한국토양비료학회지
• /
• 제11권2호
• /
• pp.89-95
• /
• 1979

규산질비료(珪酸質肥料)를 이앙(移秧) 전년(前年) 추시(秋施)했을 때와 이앙(移秧) 직전(直前) 춘시(春施)했을 때의 시용시기(施用時期) 및 입도(粒度)의 차이(差異)가 밀양 23호와 진흥의 수량(收量)에 미치는 효과를 검토할 목적(目的)으로 포장시험(圃場試驗)을 수행(遂行)하였다. 규산질비료(珪酸質肥料)의 시용(施用)(250kg/10a)에 의(依)하여 정조수량(正租收量) 및 고중(藁重)의 증가는 현저하였으나 시용시기(施用時期)에 대한 유의성(有意性)은 없었다. 입시(秋施)에 의(依)한 규산시용(珪酸施用)의 효과는 춘시(春施)한 것에 비(比)하여 다소 떨어지는 경향(傾向)을 나타낼 뿐이었다. 규산질비료(珪酸質肥料)의 입도(粒度)가 클수록 수도(水稻)의 수량(收量)에 미치는 규산시용(珪酸施用)의 효과는 떨어지는 경향(傾向)이었으나 8-25(60%)와 현행규산질비료(現行珪酸質肥料)는 대등한 것으로 평가(評價)되었다. 규산질비료(珪酸質肥料)의 시용(施用)에 의하여 대체로 주당수수와 수당입수가 증가된 반면(反面) 등숙률(登熟率)과 천립중(千粒重)은 떨어지는 경향(傾向)이었으나 추시구의 진흥에서는 입도(粒度)에 따라 수량구성요소(收量構成要素)의 변화경향이 일정(一定)치 않았다. 경엽의 규산함량(珪酸含量)은 진흥에서 높고 정조(正租)의 규산함량(珪酸含量)은 밀양23호에서 높았으며 품종간(品種間) 규산함량(珪酸含量)의 차(差)는 수확기(收穫期)보다는 이앙(移秧)50일후(日後) 식물체(植物體)에서 현저하였다. 규산함량(珪酸含量)에 미치는 시용시기(施用時期) 및 입도(粒度)의 영향은 이앙(移秧)50일후(日後) 식물체의 규산함량(珪酸含量)에서 유의성(有意性)이 인정(認定)되었으며 수확기(收穫期)의 규산함량(珪酸含量)에서는 진흥의 고중(藁中) 규산함량(珪酸含量)에 대한 입도(粒度)의 영향만이 인정(認定)되었다. 토양(土壤)의 유효규산함량은 시험전 36.7ppm에서 규산시용(珪酸施用)에 의하여 수확후(收穫後)에 춘시구에서는 159.5~273.8ppm, 추시구에서는 80.3~134.4ppm으로 증가되었다. 춘시구에서는 8-25(60%)를 시용(施用)한 경우에 가장 높았으며 추시구에서는 현행규산질비료(現行珪酸質肥料)와 8-25(60%)를 시용(施用)한 경우의 차(差)가 적었다. 결론적(結論的)으로 8-25(60%)는 현행규산질비료(現行珪酸質肥料)와 대등한 것으로 평가(評價)되며 추시(秋施)에 의(依)해서도 규산질비료(珪酸質肥料)의 효과를 충분(充分)히 얻을 수 있으나 규산질비료(珪酸質肥料)의 잔효에 대하여는 새로운 연구검토가 요구(要求)됨을 지적(指摘)하였다.

• 상하수도학회지
• /
• 제12권1호
• /
• pp.108-114
• /
• 1998

Experiments on an upgraded RBC were conducted to investigate its removal efficiencies of $NH_4-N$, coliform group and coliphage in the municipal wastewater treatment. A bench scale RBC, made of stainless mesh media with 5mm high surface protrusions, was fed with settled municipal wastewater containing 13-25mg/l of $NH_4-N$ and 40-75mg/l of TOC at the hydraulic loading of $89l/m^2.d$ and $60l/m^2.d$. It was found that the nitrification effectively occured at bulk liquid TOC concentration of less 10mg/l. The coliform group and coliphage were more than 98% and 90%, respectively.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2001년도 춘계 학술대회논문집
• /
• pp.38-44
• /
• 2001

An efficient Gauss-Seidel time integration scheme is developed for solving the Euler and Navier-Stokes equations on unstructured meshes. Roe's FDS is used for the explicit residual computations and van Leer's FVS for evaluating implicit flux Jacobian. To reduce the memory requirement to a minimum level, off-diagonal flux Jacobian contributions are repeatedly calculated during the Gauss-Seidel sub-iteration process. Computational results based on the present scheme show that approximately $15\%$ of CPU time reduction is achieved while maintaining the memory requirement level to $50-60\%$ of the original Gauss-Seidel scheme.

• 한국미생물생명공학회:학술대회논문집
• /
• 한국미생물생명공학회 1978년도 추계학술대회
• /
• pp.208.2-208
• /
• 1978

Rice Straw was delignified by autoclaving with 1％ NaOH solution at $121^{\circ}C$ for one hour and was disintegrated by a Wiley mill to 60 mesh. This substrate was saccharified with cellulase produced by Trichoderma viride T04 in solid culture me-dium. The rate and extent of hydrolysis were both increased when high enzyme concentration and low substrate concentration were employed. The original cellulose was treated with 0.19 FPA unit for three hours and followed by the second treatment for the same period with the same concentration of enzyme after washing. By doing this the hydrolysis rate at the second stage could increase four folds of that unwashed. The same experiment with 0.32 FPA unit yielded two folds suggesting an end-product inhibition on the recaction system. The extent of hydrolysis however, could not be in-creased by this process.

• 환경위생공학
• /
• 제14권4호
• /
• pp.93-98
• /
• 1999

We had investigated combustion properties of rice bran dusts. Decomposition of rice bran dusts with temperature were investigated using DSC and the weight loss according to temperature using TGA in order to find the thermal hazard of rice bran dusts, and the properties of dust explosion in variation of their dust with the same particle size. Using Hartman's dust explosion apparatus which estimate dust explosion by electric ignition after making dust disperse by compressed air, dust explosion experiments have been conducted by varying concentration and size of rice bran dust.According to the results for thermodynamic stability of rice bran dust, there are little change of initiation temperature of heat generation and heating value for used particle size. But initiation temperature of heat generation decreased with high heating rate whereas decomposition heat increased with particle size. Average maximum explosion pressure was $10kgf/cm^2$ for 60/70 mesh and $1.5mg/cm^2$ dust concentration.

• 한국식품영양과학회지
• /
• 제22권1호
• /
• pp.73-77
• /
• 1993

This study was intended to investigate the effects of solvents, particle size of a sample, sample to solvent ratio, temperature and time on the extraction of garlic oleoresin. Among eleven solvents used for oleoresin extraction from garlic, the optimal solvent was methyl alcohol. The most appropriate particle size of garlic, extracting temperature and mixing ratio of garlic to methyl alcohol were 20mesh, $25^{\circ}C$ and 1 to 3(w/w), respectively. On the basis of yield in oleoresin extraction, optimum extracting time was about 4 hours. The yield of oleoresin under the above-mentioned conditions was 21.3%. "L" and "b" as color appearance were decreased, whereas "a"was increased slightly during 60 days storage at 5$^{\circ}C$, $25^{\circ}C$ and 4$0^{\circ}C$. Changes in the pyruvate content showed close relation to pH value. During storage pyruvate content of garlic oleoresin was decreased as increasing storage temperature.