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장영기,송우석,Chang, Young Ki,Song, Woo Seok 한국압력기기공학회 2012 한국압력기기공학회 논문집 Vol.8 No.3
A seawater pumps in the nuclear power plant is responsible for providing cooling water to other components all the time. Because of the depreciation, the seawater pump with current impeller consumes too much power for maintaining the total head. Therefore the objective of this study is to reduce power with maintaining certain the total head by cutting the current impeller. By using a commercial CFD code, FLUENT, the overall performance of seawater pump with current and modified impeller was simulated. Also Affinity law was applied at pumps with various impeller diameter and evaluated the validity of the affinity law. The numerical results show that the pump efficiency is quite irrelevant to the diameters of the impellers and the pump efficiency becomes worse over the designed flow rate. And affinity law result and numerical one show good agreements at small change of impeller diameter. One of the impeller diameters was decided to modify and was applied to the nuclear power plant with the numerical study above.
설비개선이 터빈-발전기 축계의 비틀림 고유주파수에 미치는 영향 평가
이혁순(Lee Hyuk Soon),장영기(Chang young ki),오승환(Oh Seung Hwan) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Excessive torsional vibrations can result in blade failures and retaining ring failures. The severity of torsional oscillations and stress depends upon the relationship between the excitation frequencies and torsional natural frequencies. The difference between theses frequencies is referred to as the separation margin. ISO and manufacturers regulate this separation margin to ensure the system’s reliability. Recently, Turbine-generators have been replaced for the integrity reinforcement and the efficiency improvement, also, the last stage blade’s failures of LP turbines due to torsional vibration have been reported. In this paper the measured torsional vibration of the turbine-generator is analyzed to ensure the system’s reliability.
유용희,김태일,정종원,곽정훈,최희철,송준익,양창범,장영기,김호정,송기봉,Yoo Yong-Hee,Kim Tae-Il,Jeong Jong-Won,Gwak Jeong-Hun,Choi Hee-Chul,Song Jun-Ik,Yang Chang Bum,Jang Young-Kee,Kim Ho-Jung,Song Ki-Pong 한국축산환경학회 2005 축산시설환경학회지 Vol.11 No.1
본 연구는 대규모, 중규모, 소규모 양돈장을 선정 각 성장단계별 돈사내 및 부지경계선에서 악취물질 발생 농도에 대한 1차적인 기초 자료를 얻고자 수행하였다. 조사한 돈사의 형태는 무창돈사, 개방돈사이며 분뇨처리는 슬러리, 톱밥돈사 등으로 구성되어 있었다. 돈사 내에서 악취물질 발생 농도를 조사한 결과 성장단계, 사육규모에 관계없이 암모니아:0.9${\~}$21.0ppm으로 가장 높았고, 그 다음 황화수소:51.9${\~}$6,712.4ppb, 메틸머캅탄:N. D.${\~}$12.9ppb, 다이메틸설파이드:N. D.${\~}$5.2ppb, 다이메틸다이설 파이드:N. D.${\~}$2.6ppb 순으로 악취물질 발생 농도가 낮은 것으로 나타났다. 부지경계의 악취물질 농도는 돈사시설에서 풍하 방향을 고려하여 20m 외곽에서 실시하였다. 조사 당시 풍속은 0.23${\~}$0.73m/s 이었다. 악취물질 발생 농도 범위는 암모니아 0.2${\~}$4.5ppm, 황화수소 0.0l${\~}$0.06ppb, 메틸머캅탄 N. D.${\~}$0.009ppb, 다이메틸다이설파이드 N. D.${\~}$0.002ppb가 측정되었다. 악취물질별로 돈사 내 및 부지경계 기준악취물질 발생농도를 비교한 결과 악취물질 발생농도는 다이메틸설파이드 가장 낮게 검출되었으며 그 다음 황화수소, 암모니아, 메틸머캅탄, 다이메틸다이설파이드 순으로 검출되었다. 금후 돈사 내 악취물질 발생 및 그 원인에 대하여는 돈사 내$\cdot$외 환경 여건 변화에 따라 다양하므로 좀더 많은 연구가 필요한 것으로 판단된다. A field survey was conducted to determine the concentration of odor compounds from pig buildings and that were 20 meters within the boundary area. The odor compounds were measured from large, medium and small farms with enclosed and open housing systems and slurry and sawdust manure fermentation treatment methods. Among the odor compounds investigated, ammonia ($NH_3$) had the highest concentration at 0.9 ${\~}$ 21.0 ppm followed by Hydrogen Sulfide($H_2S$) with a wide variation concentration of 51.9 ${\~}$ 6,712.4 pub, Uethylmercaptan($CH_3SH$) with non-detectable (N. D.) ${\~}$ 12.9 ppb, Dimethylsulphide($(CH_3)_2S$), with N. D. ${\~}$ 5.2 ppb and Dimethyldisulphide($(CH_3)_2S_2$) with N. D. ${\~}$ 2.6 ppb. Considering the prevailing wind direction and air velocity ranging from 0.23 to 0.73 m/s within the boundary area, the odorous matters; $NH_3$, $H_2S$, $CH_3SH$, $(CH_3)_2S_2$ and $(CH_3)_2S$ were 0.2${\~}$4.5 ppm, 0.01 ${\~}$0.06 ppb, N. D. ${\~}$0.009ppb, N. D.${\~}$0.002ppb and N. D. for $(CH_3)_2S$ respectively. These findings suggested that the Odor compounds $(CH_3)_2S_2$ had the lower detection in the boundary area whilst $(CH_3)_2S$ had no detection level within a 20-meter distance only. However, with these results odor compounds from pig buildings has to be further investigated under more controlled environmental factors.
공기열원 히트펌프 시스템 실내 응축기 성능 특성에 관한 실험적 연구
이호성(Ho-seong Lee),원종필(Jong-phil Won),조중원(Choong-won Cho),장영기(Young-ki Chang),임택규(Taek-kyu Lim),전한별(Han-byoel Jeon),김용찬(Yong-chan Kim) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.- No.-
The development of eco-friendly cars due to global warming. The main problem is the relatively short when compared to the existing mileage per charge of the electric vehicle is a problem. In this situation, because the electrical energy must be spent for heating electric vehicles reduced mileage per charge. Heating performance is studied for air heat source heat pump system. In this study, experiment to analyze heating performance characteristics with air heat source have been with various operating conditions, which are likely to match the air heat source Heat pump system operating conditions under cold ambient conditions, such as variation of compressor speed and interior air temperature. Ambient temperature down from 5℃ to –10℃ occurs reduction of heating capacity of inner condenser due to reduction of refrigerant flow rate in accordance with reduction of 45% density of refrigerant. Increasing compressor speed from 2000 RPM to 3,500 RPM occurs increasing of heating capacity of inner condenser. But COP of heat pump system is reduced 26% due to additional compressor power. It seems a good way to study for a plan to try to increase inner condenser air flow rate, inner heat exchanger area.
권태인,장영기 國立 昌原大學校 基礎科學硏究所 1993 基礎科學硏究所論文集 Vol.4 No.-
R을 단위원을 갖는 환, P를 우측 R-가군이라 하자. R의 ideaⅠ에 대하여 P의 모든 부분가군이 P/Ⅰ형 일때 P를 곱셈가군이라 한다. 본 논문에서는 곱셈가군의 여러성질(정리 3.1)에 대하여 연구한다.
張榮基 서경대학교 인문과학연구소 1997 人文科學硏究 Vol.4 No.-
詩之用典, 赤謂之用故實, 學凡前代之文章成語與夫人物典故屬之1). 劉勰 「文心雕龍」 取名曰事類. 也「事類篇」 云.. 事類者, 蓋文章之外, 據事以類義, 援古以證今者也. 所謂事類, 蓋卽在文辭章法之外. 依據事情以類比義理, 援引往古以證驗來今之修辭方法又云..