• Title/Summary/Keyword: 김욱일

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Characteristics of Plane Impinging Jets(2)- Cylinder-tone - (평면 충돌제트의 불안정특성(2)-원통음-)

  • Kwon, Young-Pil;Kim, Wook;Lee, Joo-Won
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.2
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    • pp.105-110
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    • 2004
  • The objective of this study is to obtain the instability characteristics of the plane jet impinging on circular cylinder associated with the cylinder-tone. It is found that the characteristics depends upon he ratio of the cylinder diameter to the nozzle width, D/h, and the jet velocity. When the ratio is oderate the cylinder-tone is similar to the edge-tone. With increase of the ratio, its characteristics ecomes similar to that of the plate-tone in which only the high-speed tone associated with turbulent et is generated. When D/h 〈1. the frequency range, especially the lower limit of frequency, is ignificantly influenced by the cylinder diameter. At around D/h = 1/2, while low speed tones are nduced with the antisymmetric mode of instability and affected by the vortex shedding from the ylinder, high-speed tones are generated, at first, with the symmetric mode of instability. and then, ith antisymmetric mode, as the jet velocity increases.

A Study on Nonlinear Spatial Filter using Directional Information of Image (영상의 방향성 정보를 이용한 비선형 공간필터에 관한 연구)

  • Kim, Uk;Bae, Sang-Bum;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2007.10a
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    • pp.359-362
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    • 2007
  • According to the development of information and communication technology, a great deal of researches have been taken in image digital processing field. And for earning the standard level of images, to remove noises such as impulse noise has became a essential demand. In those algorithms which remove impulse noise effectively, the standard median (SM) filter is representative. However, it has a disadvantage to degrade the quality of overall image by occurring errors in the edge domain. Therefore, in this paper, to restore the corrupted image by impulse noise, a nonlinear spatial filter based on Min-max operation was proposed and it was compared with conventional methods through simulations.

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CFD Analysis on a Tall Building Augmented Wind Turbine (풍력발전기가 설치된 고층빌딜에 대한 전산유체역학적 고찰)

  • Jeon, Wan-Ho;Yoon, Seong-Wook;Kim, Wook;Cho, Jang-Hyung
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.418-421
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    • 2009
  • Renewable energy or green energy is a hot issue in theses days. Since wind resource can be endlessly supplied by nature, researchers and common people are interested in study how to use that resource at home or company. Especially, many architects have tried to integrate wind power generator for a part of building. So in this paper, three buildings installed wind power turbine are targed to CFD analysis and these buildings are Bahrain trade center, Discovery tower, and Pearl river tower. Bahrain trade center is the first builidng installed real wind turbine, Discovery tower is constructing at Texas, and Pearl river tower is designed and proved by china researchers. These buildings have very different type of wind power turbine and each turbine has different conditions for best power generation. Therefor this paper will focus on characteristic shape of buildings, wind power turbine type, and expected purpose of construction. Moreover, CFD analysis will show wind flow pattern and wind speed while wind is passing through wind turbine of three tall buildings. CFD analysis for three buildings make comparison the wind flow patterns with experimental result.

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A Numerical Study on Flow through a Cross Flow Fan: Effect of Blade Shapes on Fan Performance (직교류 홴의 유동 해석: 깃 형상 변화가 성능에 미치는 영향)

  • Hur, Nahm-Keon;Kim, Wook;Kang, Shin-Hyoung
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.1 s.2
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    • pp.96-102
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    • 1999
  • Cross flow fans are used in various applications, especially in industrial ventilation applications and in room air conditioners, due to their superior performance characteristics. Unlike radial and/or axial fans, the design of cross flow fans have been mostly based on earlier experiences and experiments. In the present study, numerical computations of flow fields through a cross flow fan used in room air conditioner are performed to investigate the detailed flow fields and to study the effect of the blade shape on performance curves to aid better design of the fan. Despite some discrepancies between the two results, it is seen from the present study that the computational results agree quite well with the qualitative experimental results. It is also shown from the present study that by having a different shape of blade, it is possible to achieve about $15\%$ increase in flow rates. The stimulating results of the present study can be used in the design of high performance cross flow fans with the use of optimal design algorithm and experimental verifications.

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A Study on the Estimation of Optimal ESS Capacity Considering REC Weighting Scheme (REC 가중치를 고려한 최적 ESS 용량 산정에 관한 연구)

  • Lee, Sungwoo;Kim, Hyoungtae;Shin, Hansol;Kim, Tae Hyun;Kim, Wook
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.8
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    • pp.1009-1018
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    • 2018
  • As the generation of renewable energy increases rapidly, the stability of the grid due to its intermittency becomes a problem. The most appropriate way to solve this problem is to combine and operate the renewable generators with the ESS(Energy Storage System). However, since the revenues of operating the ESS are less than the investment cost, many countries are implementing various incentive policies for encouraging investment of the ESS. In this paper we estimated optimal capacity of the ESS to maximize profits of renewable energy generation businesses under the incentive policy of Korea and analyzed the impact of the incentive policy on the future electric power system of Jeju island. The simulation results show that the incentive policy has significantly improved the profitability of the renewable energy businesses generation business. But the volatility of the net demand has increased as the energy stored in the ESS is discharged intensively at the time of the incentive application.

An Analysis of Characteristics of Musculoskeletal Disorders Risk Factors (산업재해 중 근골격계질환 요인 특성 분석)

  • Kim, Hyun-Ho;Park, Hyun-Jin;Park, Ki-Hyuk;Kim, Wook;Yoo, Chan-Young;Kim, Jeung-Ho;Park, Jung-Sun
    • Journal of the Ergonomics Society of Korea
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    • v.28 no.3
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    • pp.17-25
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    • 2009
  • This study was aimed to analyze of characteristics of Musculoskeletal disorders (MSDs) based on the industrial accident statistics which were extracted from the Ministry of Labor. In this study all MSDs cases in 2007, 7,723 cases, were investigated. First of all, for the analysis of a wide view point concerning the characteristics of MSDs, We have inspected characteristics of the user population (i.e. age, gender, employed periods, etc.). Secondly, work-related risk factors such as repetitive motions, awkward postures, manual material handling were analyzed in terms of disease code, injured part of body, types of business, etc. Next, characteristics of handling of heavy materials were analyzed according to weight, types of handling, agency of cause, etc. Finally, we have compared and analyzed the features between the period of hospitalization and other variables. In addition to that we also conducted statistics analysis. The study results showed that there were significant characteristics of MSDs that could be used as basis data for the MSDs prevention policy.

PCR-Based Polymorphic Analysis for the Y Chromosomal Loci DYS19 and DXYS5Y (47z) in the Korean Population

  • Shin, Dong-Jik;Kim, Yung-Jin;Kim, Wook
    • Animal cells and systems
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    • v.2 no.2
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    • pp.281-285
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    • 1998
  • We examined Y chromosomal DNA polymorphisms at the DYS19 and DXYS5Y loci in a total of 480 unrelated male samples from the Korean population. All five common alleles were identified at the tetranucleotide microsatellite locus DYS19 in this study. The C allele was the most frequent (212/480), followed by D (136/480), B (75/480), E (36/480) and A (21/480) allele. The frequency of Y2 allele at the DXYS5Y locus was found to be 4.6% (22/480). Combining the allelic variation at these two loci resulted in a total of 9 combination haplotypes. The mean combination haplotype diversity wIns 0.72. Based on the results of these two loci, Korean and Japanese populations may share some common genetic structure that is rare or absent in the other ethnic groups. The genetic similarity between Korean and Japanese populations may be due to the large infusion of Y chromosomes through the Yayoi migration starting 2,300 years ago from Korea to Japan.

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Pre-treatment Condition for Inhibiting of Germination in Cotton Seeds (면실 종자의 발아억제를 위한 전처리 조건 연구)

  • Kim, Jae Yoon;Kwon, Hyeok;Lee, Yong Ho;Hong, Sun Hee;Son, Yong Suk;Kim, Wook
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.58 no.1
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    • pp.67-70
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    • 2013
  • This research study was to develop methods for inhibiting the germination of cotton seeds. Germination rates after heating treatment at $80^{\circ}C$ with 10, 20, 30, 40 min. were 9.3, 9.3, 5.3 and 1.3 percentage, respectively. Heat treatment over $85^{\circ}C$ with 10 min. caused no germination of cotton seeds. Germination was significantly reduced with gamma rays treatment more than 10,000 gy, while the treatment within 2,000-8,000 gy induced less effects. Microwave processing for 30 seconds and 60 seconds inhibit the germination of cotton seed under 8 and 0%, respectively. As a physical treatment, rollmill milling with 1.5, 2, 2.5 mm gap inhibited any germination of cotton seeds. The optimum gap of roll-mill for processing physical cracking was below 51% of the thickness of seed.

Simulation of photon propagation for transcutaneous optical communication (피부투과 광통신을 위한 세포내 광진행 시뮬레이션)

  • Lee, J.J.;Kim, W.E.;Lee, J.H.;Choi, J.H.;Ahn, J.M.;Choi, W.W.;Park, S.K.;Choi, J.S.;Kim, H.C.;Min, B.G.
    • Proceedings of the KOSOMBE Conference
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    • v.1996 no.11
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    • pp.65-67
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    • 1996
  • Optical property of tissue is characterized by its high scattering of light. In near infrared range$(800{\sim}1200nm)$ scattering is dominant than absorption. Communication using NIR through tissue is applicable to immplantable device. In this paper, simulation of unit impulse response of light in tissue is carried out to estimate the amplitude, phaselength and phaselength deviation.

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Optimization of Long-term Generator Maintenance Scheduling considering Network Congestion and Equivalent Operating Hours (송전제약과 등가운전시간을 고려한 장기 예방정비계획 최적화에 관한 연구)

  • Shin, Hansol;Kim, Hyoungtae;Lee, Sungwoo;Kim, Wook
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.2
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    • pp.305-314
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    • 2017
  • Most of the existing researches on systemwide optimization of generator maintenance scheduling do not consider the equivalent operating hours(EOHs) mainly due to the difficulties of calculating the EOHs of the CCGTs in the large scale system. In order to estimate the EOHs not only the operating hours but also the number of start-up/shutdown during the planning period should be estimated, which requires the mathematical model to incorporate the economic dispatch model and unit commitment model. The model is inherently modelled as a large scale mixed-integer nonlinear programming problem and the computation time increases exponentially and intractable as the system size grows. To make the problem tractable, this paper proposes an EOH calculation based on demand grouping by K-means clustering algorithm. Network congestion is also considered in order to improve the accuracy of EOH calculation. This proposed method is applied to the actual Korean electricity market and compared to other existing methods.