• 한국전산유체공학회지
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• 제17권3호
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• pp.39-44
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• 2012

In this study, a longitudinal pitch effect on in-line tube bank heat transfer has been analyzed numerically. To verify the accuracy of the solver model and boundary conditions, global Nusselt number(Nu) and pressure drop across the 2 row tube bank are compared with the existing experimental correlations under 500 ~ 2,000 Reynolds number(Re) range. By changing transverse pitch($S_T$) or longitudinal pitch($S_L$) separately in tube bank, we're trying to identify the each effect on heat transfer. We found that the effect of transverse pitch can be accounted for Reynolds number evaluated with maximum velocity($V_{max}$) at the smallest flow area similar to most existing correlations. Variation of the longitudinal pitch($S_L$) has a greater impact on the heat transfer compared to the transverse pitch($S_T$). Overall Nusselt number increases with larger longitudinal pitch($S_L$), however individual Nusselt number of the tube row has significant difference after the first row.

• 대한기계학회논문집B
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• 제31권4호
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• pp.335-340
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• 2007

A new correlation between the Nusselt number based on modified heat transfer coefficient and Reynold number based on droplet-flow-rate was developed for the experimental data. The modified heat transfer coefficient was defined as ratio of wall heat flux to droplet subcooling. In the previous reports, the local heat flux of spray cooling in the film boiling region was experimentally investigated for the water spray region of $D_{max} = 0.0007{\sim}0.03m^3/(m^2s)$ . In the region near the stagnation point of spray flow, a new heat transfer correlation is recommended which shows good predictions for the water spray region of $D_x{\le}0.01m^3/(m^2s)$.

• 태양에너지
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• 제15권3호
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• pp.105-117
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• 1995

본 연구소에서는 Furan foundry sand 유동층내에 Spiral coil tube를 설치하여 유동입자, 유동층내 온도, 유동율, 전열 관의 Pitch와 직경 비(p/Do) 및 전열 관의 Pitch와 유동입자의 크기의 비(p/dp) 등이 전열 관 표면 열 전달계수(ho)에 미치는 영향을 실험적으로 연구하고, 또한 최대 $Nu_{max}$수를 여러 변수들의 관계로 나타내었다. 전열 관 표면 열 전달계수는 유동층내 온도가 높아 질 수록, 유동율이 커질수록 증가한다. 그러나 유동입자의 크기가 커지면 열 전달계수는 감소한다. 전열 관의 Pitch와 직경 비(p/Do)와의 관계에서 p/Do=4.75일 때 가장 높은 열 전달계수를 얻었으며, 유동층내 온도가 상승하고, Re 수가 증가할 수록 p/Do=1.58일 때보다 p/Do=4.75일때가 Nu수의 증가율은 다소 감소하는 경향을 보였다. 또한 p/dp의 비가 클 경우 낮은 온도($75^{\circ}C$)에서, p/dp의 비가 작을 경우는 높은 온도($550^{\circ}C$)에서 열 전달 효과가 큰 것으로 나타났다. 본 실험범위에서 최대 $Nu_{max}$ 수와 Re 수, Prg 수, p/dp 및 p/Do의 관계를 무차원 식으로 다음과 같이 나타낼 수 있었다. $$Nu_{max}=1.01\;Re^{0.48}Prg^{0.4}(p/dp)^{0.28}(p/Do)^{0.05}$$.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.285-290
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• 2000

The present study was conducted to determine flooding heat transfer limitation of a two-phase closed thermosyphon using PFC as working fluid. The variables such as pipe inner diameter, working fluid property, operating temperature were examined by way of analytic method. Comparison of experimental data on flooding heat transfer limitation shows a fairly good agreement with the analytic results. An expression fur flooding maximum heat transfer rate was formulated as a function of Bond number and saturation pressure and written as follows ; $Q_{max} =0.989{\cdot}P_s^{0.286}{\cdot}Bo^{1.74}$.

• 대한화학회지
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• 제26권5호
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• pp.274-281
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• 1982

펜타메틸벤젠 및 헥사메틸벤젠과 요오드 및 일염화요오드와의 각계를 사염화 탄소용액에서 자외선 분광광도법에 의하여 연구한 결과 1:1 분자 착물이 형성됨을 알았다. 이들 착물 생성에 의한 흡수최대는 온도가 상승함에 따라 blue shift 되므로 이에 따른 각 온도에서의 평형상수를 구하였다. 이 값으로 부터 이들 착물 생성에 대한 열역학적 파라미터를 산출한 결과 각 온도에서 폴리메틸벤젠과 요오드 및 일염화요오드 사이에 생성된 착물의 상대적 안정도는 ICl이 $I_2$보다 크다는 것을 알 수 있다. 이 사실은 폴리메틸벤젠에 대한 그들의 상대적 산성도를 나타내며 할로겐 원자의 전기 음성도의 차이에 의하여 설명할 수 있다. 그리고 이 계열의 연구결과를 종합하면 벤젠에 치환된 메틸기의 수가 증가함에 따라 ${\lambda}_{max}$는 red shift 하였고 이들 착물의 상대적 안정도가 다음 순서로 증가함을 알 수 있었다.Benzene < Toluene < Xylene < Durene < Mesitylene < Pentamethylbenzene < Hexamethylbenzene. 이에 따른 결과에 대하여 고찰하였다.

• 한국ITS학회 논문지
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• 제4권1호
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• pp.1-13
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• 2005

다양한 대중교통수단이 함께 구축되어 있는 통합대중교통망(Integrated Transit Network)에 대하여, 최적통행시간 경로정보뿐만 아니라 다수의 최적통행시간 정보를 제공하는 방안에 대한 기초연구는 그 사례를 찾아보기 어렵다. 본 연구는 다수의 대중교통경로를 탐색하기 위하여, 버스와 지하철의 두 수단이 함께 존재하는 복합교통망에서 K개의 최소통행시간을 갖는 경로를 탐색하는 방안을 제안한다 제안된 방안은 통행정보에서 대중교통 사용자가 일반적으로 필요로 하는 다음의 3가지 제약조건 (1) 수단의 서비스시간제약, (2) 통합거리비례제 요금제약, 3) 환승회수제약을 고려한다. 사례연구를 통해 K개의 최소통행시간 경로정보뿐만 아니라 위의 제약조건을 조합적으로 반영하여 사용자에게 필요한 경로정보의 질적 향상 및 다양화에 대한 가능성을 제시한다.

• 대한기계학회논문집
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• 제5권4호
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• pp.329-337
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• 1981

Natural convection within inclined high aspect-ratio rectangular cavity was analysed by using finite element method. For a cavity of sapect-ratio 20, the flow patterns of secondary vortices and the heat transfer characteristics on the wall were obtained with the variation of tilt angle as well as Ra and Pr. The observation on the governing equations shows that the increase of Ra/Pr and the existence of nonzero tilt angle make the flow pattern more complicated and so it becomes difficult to obtain converging solution. The max. value of Ra/Pr attained in this study was 3x10$\^$4/at 0$\^$0/ tilt angle and 1.1x10$\^$4/ at 45.deg. tilt angle for aspect ratio 20and Pr=0.7. Finally an empirical formula for Nusselt number which can accout for the effect of tilt angle is obtained for laminar flow regime.

• Journal of Plant Biology
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• 제37권3호
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• pp.333-341
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• 1994

Effective plant regeneration from immature cotyledons of soybean [Glycine max (L.) Merr.] cultivars was achieved via somatic embryogenesis. Somatic embryogenesis was performed with the cotyledons of immature embryos 14-20 d after flowering. Immature cotyledons of cv. Whangkeum were placed abaxial or adaxial side down on modified MS medium containing 20mg/L 2,4-D. The greatest number of somatic embryos, 1.2 per cotyledon, was produced from those of 4.0-4.9 mm in length which had been placed abaxial side down. Among cvs. Pecking, Whangkeum and Baekwoon, Pecking had the highest embryo induction efficiency with 4.3 somatic embryos per cotyledon in 20mg/L 2,4-D treatment and with 1.0 embryo per cotyledon in 8mg/L NAA treatment. Germinable globular somatic embryos were induced with the highest efficiency, 27.6%, in 20mg/L 2,4-D and were proliferated efficiently on liquid medium containing 10mg/L 2,4-D. The globular somatic embryos developed into germinable mature somatic embryos on medium containing 10 $\mu$M CoCl2, 9% sucrose, and 0.5% activated charcoal. These mature somatic embryos germinated on hormone-free mediu. After transfer to the soil, regenerated plants with seeds were obtained.

• ETRI Journal
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• 제46권2호
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• pp.290-306
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• 2024

To treat the novel COronaVIrus Disease (COVID), comparatively fewer medicines have been approved. Due to the global pandemic status of COVID, several medicines are being developed to treat patients. The modern COVID medicines development process has various challenges, including predicting and detecting hazardous COVID medicine responses. Moreover, correctly predicting harmful COVID medicine reactions is essential for health safety. Significant developments in computational models in medicine development can make it possible to identify adverse COVID medicine reactions. Since the beginning of the COVID pandemic, there has been significant demand for developing COVID medicines. Therefore, this paper presents the transferlearning methodology and a multilabel convolutional neural network for COVID (MLCNN-COV) medicines development model to identify negative responses of COVID medicines. For analysis, a framework is proposed with five multilabel transfer-learning models, namely, MobileNetv2, ResNet50, VGG19, DenseNet201, and Inceptionv3, and an MLCNN-COV model is designed with an image augmentation (IA) technique and validated through experiments on the image of three-dimensional chemical conformer of 17 number of COVID medicines. The RGB color channel is utilized to represent the feature of the image, and image features are extracted by employing the Convolution2D and MaxPooling2D layer. The findings of the current MLCNN-COV are promising, and it can identify individual adverse reactions of medicines, with the accuracy ranging from 88.24% to 100%, which outperformed the transfer-learning model's performance. It shows that three-dimensional conformers adequately identify negative COVID medicine responses.

• 대한전기학회논문지:전력기술부문A
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• 제53권11호
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• pp.596-603
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• 2004

This paper proposes an expert system based on the pattern recognition method which can enhance the accuracy and effectiveness of real-time bus reconfiguration strategy for the transfer of faulted load when a main transformer fault occurs in the automated substation. The minimum distance classification method is adopted as the pattern recognition method of expert system. The training pattern set is designed MTr by MTr to minimize the searching time for target load pattern which is similar to the real-time load pattern. But the control pattern set, which is required to determine the corresponding bus reconfiguration strategy to these trained load pattern set is designed as one table by considering the efficiency of knowledge base design because its size is small. The training load pattern generator based on load level and the training load pattern generator based on load profile are designed, which are can reduce the size of each training pattern set from max L/sup (m+f)/ to the size of effective level. Here, L is the number of load level, m and f are the number of main transformers and the number of feeders. The one reduces the number of trained load pattern by setting the sawmiller patterns to a same pattern, the other reduces by considering only load pattern while the given period. And control pattern generator based on exhaustive search method with breadth-limit is designed, which generates the corresponding bus reconfiguration strategy to these trained load pattern set. The inference engine of the expert system and the substation database and knowledge base is implemented in MFC function of Visual C++ Finally, the performance and effectiveness of the proposed expert system is verified by comparing the best-first search solution and pattern recognition solution based on diversity event simulations for typical distribution substation.