연구 - 한국의 계절별 계사의 부하 특성 연구

권영철,Gwon, Yeong-Cheol 대한양계협회 2019 월간 양계 Vol.51 No.8

본고는 금년 4월 26일 고려대학교에서 개최된 (사)대한건축학회 춘계학술발표대회에서 한라대학교 권영철 교수가 발표한 '한국의 계절별 계사의 부하 특성에 관한 연구' 내용을 발췌하여 게재하였다. 본 연구는 매년 여름 폭염으로 인한 닭들의 폐사를 줄이고 최적 단열 및 환기 방안을 마려하기 위한 연구의 일환으로 이루어졌다.

삽입물에 의한 관내 층류열전달 증진에 관한 실험적 연구

권영철,장근선,정지환 대한설비공학회 2000 설비공학 논문집 Vol.12 No.7

In order to understand the laminar flow heat transfer enhancement by the swirl flow, the effects of heat transfer in a circular pipe with a twisted tape insert were investigated experimentally. In the present study, the uniform heat flux condition was considered. The laminar heat transfer correlations were developed using the least-square-fit from the surface temperature distribution of an electrically-heated pipe and flow property data. Average Nusselt number correlations with the twisted tape insert were expressed as a function of swirl parameter, Reynolds number and Prandtl number. In the case of the twisted ratio y = 6.05, the mean Nusselt number increased approximately 500% and the friction factor increased approximately 300%, compared to the case of the empty pipe, respectively.

고출력 광섬유 레이저 기술의 현황 및 전망

권영철,박경윤,이동열,장한별,이승종,루이스 알론소 바즈게즈 주니가,이용수,김동환,김현태,정윤찬,Kwon, Youngchul,Park, Kyoungyoon,Lee, Dongyeul,Chang, Hanbyul,Lee, Seungjong,Vazquez-Zuniga, Luis Alonso,Lee, Yong Soo,Kim, Dong Hwan,Kim, Hyun Tae 한국광학회 2016 한국광학회지 Vol.27 No.1

최근 20 여년간의 괄목할만한 발전을 통해 단일 광섬유 레이저의 출력은 이미 kW 수준을 상회하고 있으며, 기존의 벌크 방식 레이저의 대체 기술로서 여전히 학계 및 산업계의 뜨거운 관심을 받고 있다. 본 논문은 이와 같은 광섬유 레이저의 괄목할만한 성장을 가능하게 한, 이터븀(Ytterbium) 혼입 이득 광섬유 사용 방식, 레이저 다이오드 펌프와 이중 클래딩 광섬유 구조를 통한 광학적 펌프 방식, 더 나아가서 양자결함을 최소화 하는 종렬 펌핑 방식 등 그 주요 요소 기술들을 개괄하고, 그 극한적 고출력화에 따른 발진 효율 및 특성 저하, 시스템 열화 및 불안정성 증대 등과 같은 고출력 광섬유 레이저 기술 자체가 직면하고 있는 다양한 기술적 문제점 및 그 완화 방안을 논의한다. 여기에서는 광섬유 레이저의 고출력화와 더불어 야기되는 다양한 형태의 광섬유내 비선형 현상, 광섬유 손상 및 모드 불안정 현상에 대한 논의를 포함한다. 이와 더불어, 전술한 다양한 출력 제한 현상을 극복함과 동시에 광섬유 레이저의 출력을 현격한 수준으로 더욱 증가시키기 위한 대체 방안으로 최근 주목을 많이 받고 있는 다중 빔 결합 기술에 대해 개괄적으로 논의한다. 특히, 분광형 다중 빔 결합 기술의 개념적 시스템 구성 요소 및 각 부문별 요구 기술에 대해 보다 심화된 논점을 둔다. 최종적으로 현 수준을 뛰어 넘는 광섬유 레이저의 출력 증대와 본 기술의 지속적 발전을 위한 앞으로의 발전 방향을 논의한다. Over the past two decades, fiber-based lasers have made remarkable progress, now having reached power levels exceeding kilowatts and drawing a huge amount of attention from academy and industry as a replacement technology for bulk lasers. In this paper we review the significant factors that have led to the progress of fiber lasers, such as gain-fiber regimes based on ytterbium-doped silica, optical pumping schemes through the combination of laser diodes and double-clad fiber geometries, and tandem schemes for minimizing quantum defects. Furthermore, we discuss various power-limitation issues that are expected to incur with respect to the ultimate power scaling of fiber lasers, such as efficiency degradation, thermal hazard, and system-instability growth in fiber lasers, and various relevant methods to alleviate the aforementioned issues. This discussion includes fiber nonlinear effects, fiber damage, and modal-instability issues, which become more significant as the power level is scaled up. In addition, we also review beam-combining techniques, which are currently receiving a lot of attention as an alternative solution to the power-scaling limitation of high-power fiber lasers. In particular, we focus more on the discussion of the schematics of a spectral beam-combining system and their individual requirements. Finally, we discuss prospects for the future development of fiber laser technologies, for them to leap forward from where they are now, and to continue to advance in terms of their power scalability.

Effects of an electric field on the dynamic characteristics of bubbles in nucleate boiling

권영철,장근선,권정태,김무환 대한설비공학회 2000 설비공학 논문집 Vol.12 No.11

In order to investigate the effects of an electric field on EHD (Electro-hydro-dynamic) nucleate boiling heat transfer characteristics in a nonuniform electric field under saturated pool boiling, the basic study has been performed experimentally. In the present study, the working fluid is R-113 and the plate-wire electrode system is used to generate a steep electric field gradient. Boiling parameters are investigated by using a high speed camera. The electric field distribution around a wire is obtained to understand the effect of an electric field on bubble departure/movement. The experimental results show EHD effects are much more considerable when the applied voltage increases. Bubbles depart away from the heated wire in radial direction. It is confirmed that the mechanisms of EHD nucleate boiling are closely connected with the dynamic behavior of bubbles. The boiling parameters are significantly changed by the electric field strength. With increasing applied voltages, the bubble size decreases and the nucleation site density, bubble velocity and bubble frequency increase.

혹서기 양계관리 중점 사항 - 양계장 단열의 중요성

권영철,Gwon, Yeong-Cheol 대한양계협회 2018 월간 양계 Vol.50 No.6

Asymptotic Behavior of Solutions for the Delay Semilinear Fuzzy Integrodifferential Systems

권영철,박동근,이부영,황진수 한국지능시스템학회 2010 한국지능시스템학회 학술발표 논문집 Vol.20 No.2

In this paper, we study the asymptotic behavior of solutions for the delay semilinear fuzzy integrodifferential systems on E 1/N.

植栽密度가 리기다소나무苗의 生長에 미치는 影響

權泳徹 진주산업대학교 1980 論文集 Vol.18 No.-

리기다소나무 1­-1苗를 生産하는데 보다 더 效果的인 方法을 模索하고자 本大學의 苗圃場에서 리기다소나무 1年生苗를 植栽密度別로 床替하여 生長狀態를 試驗한 結果를 要約하면 다음과 같다. 1. 植栽密度가 낮은 C區, D區 및 E區는 植栽密度가 높은 A區와 B區보다 生育空間이 比較的 넓어서 苗高生長이 좋았다. 2. 根元徑生長도 植栽密度가 낮은 C區, D區 및 E區가 좋았다. 3. 枯死率은 各區 모두 僅少하게 나타났으며, 植栽密度와는 關係가 없었다. 4. 리기다소나무 1­-1苗의 養苗는 合格苗의 得苗本數가 많고 得苗比率이 比較的 높은 C區로 床替하는 것이 1年生苗의 損失이 적고 床替하는 勞動力도 節約된다고 생각된다. These studies were carried out know the effective way in order to produce 1-­1 Pinus rigida seedlings, and therefore they were transplanted as each planting density in this college's forestry seedbed and were investigated the growth by planting desity. The results are summarized as follows; 1. In the case of C. plot, D. plot, and E. plot of low planting density the top height growth was shown better than A. plot and B, plot of high planting density owing to have large width. 2. The root caliper growth was also showed to be good in C. plot, D. plot and E. plot of low panting density. 3. In the case of each plot, there was a similar ratio of withering and death and it was not related to planting density. 4. Based on the above-­mentiond results, it was concluded that 1-­1 Pinus rigida seedling should be transplanted at C. plot gainning much seedling by standing test and for that reason the expenses and labors were subtracted by it.

패시브 하우스를 위한 고효율 단열재

권영철 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.11

床替密度가 삼나무苗의 生長에 미치는 影響

權泳徹 진주산업대학교 1981 論文集 Vol.19 No.-

삼나무 1-1苗를 生産하는데 보다 더 效果的인 방법을 摸索하고자 本大學의 苗圃場에서 삼나무 1年生苗를 密度別로 床替하여 生長狀態를 試驗한 結果를 要約하면 다음과 같다. 1. 床替密度가 낮은 C區, D區 및 E區는 床替密度가 높은 A區 및 B區보다 苗高生長이 좋았다. 2. 根元徑生長도 C區, D區 및 E區가 좋았다. 3. 床替密度가 높은 A區와 B區는 9月과 10月에 苗木이 많이 枯死되었으며, 枯死率도 높았다. 4. 삼나무 1-1苗의 養苗는 合格苗의 得苗本數가 많고 得苗比率이 比較的 높은 C區로 床替하는 것이 1年生苗의 損失이 적고 床替하는 勞動力도 節約된다고 생각된다. These studies were carried out investigate the effective way in order to produce 1-1 Japanese Ceder(Cryptomeria japonica D. Don) seedings, and therefore they were transplanted 1-0 Japanese Ceder seedings as each density in this College’s forestry seedbed and the growth were investigated by transplanting density. The results were summarized as follows. 1. In the case of C. plot, D. plot and E. plot of low transplanting density the height growth was shown better than A. plot and B. plot of high transplanting density. 2. The root caliper growth was also showed to be good in C. plot, D. plot, and E. plot of low transplanting density. 3. In A. plot and B. plot of high transplanting density was dead extremely much on September and October, and withering dead ratio was high. 4. Based on the above- mentiond results, it was concluded that 1-1 Japanese Ceder seedlings should be transplanted in C. plot gaining much seedling by standing test and for that reason the expenses and labors were subtracted by it.

方位別로 測定한 소나무의 胸高直徑과 根元直徑과의 關係에 關한 硏究

權泳徹,金在慶 진주산업대학교 1969 論文集 Vol.3 No.-

樹木에 있어서 直徑의 偏倚生長原因은 常風뿐만 아니라 立地, 울폐도, 병충해 등 諸原因이 綜合作用하여 일어나는 것으로 생각되나 위선 常風의 方向과 方位에 關한 林木의 直徑生長과 어떤 關係가 있는 것인가를 알고저 河東邑所在 松林의 林木들에 關해서 方位別로 測定한 根元直徑과 胸高直徑과의 關係를 要約하면 다음과 같다. 1. 幹의 橫斷面은 楕圓形으로서 長軸의 方向이 이 地方의 常風의 方向과 一致하여 直徑이 커져서 偏倚生長을 하고 있음이 인정되었다. 2. 根元直徑에서 胸高直徑을 算出하는 關係式 D=0.8214 D'-0.395의 式을 決定하였다. 3. 胸高 및 根元直徑과의 相關係數를 보면 NS의 方向에서 γ=+0.961±0.0196, EW의 方向에서 γ=+0.847±0.0020으로서 高度의 相關關係가 있음이 인정되었다. It's thought of that the ellipic growth of the diameter in the trees often results from the several causes, that is, the constant wind, the site, the degree of closure and the insect pests. But to know correctly what kind of relation exists between the course and direction and the diameter growth of the forest trees, I calcurated the relation between the diameter of breast height and the diameter of root-stock of the forest trees at HA DONG SONG LIM. The results of this study are as follows; 1) It was found that the cross section of the stem is a elliptical orbit and the direction of the long axis and the derection of the cinstant wind in this region agreed between themselves and the diameter grows as the ellipic growth. 2) It was decided that a formula to calculate the diameter of breast height from the diameter of root-stock, that is, D=08.214,D-0.395 3) According to the correlation coefficient between the daimeter of breast height and the diameter of root-stock, there was a high state correlation, that is, in the direction N S, R=+0,961±0,0196 and in the direction E W, R=+0,847±0,0020.