• 대한전기학회논문지
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• 제43권7호
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• pp.1127-1134
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• 1994

The analytical model for the induced Hall field in the magnetotransistor considering the diffusion of carriers has been proposed and verified by experiment and simulation. Previous models for the induced Hall field in the magnetotransistor do not consider the influence of the diffusion carrier transport. However, the carrier diffusion in the base region of magnetotransistors cannot be neglected and should be considered to evaluated the Hall field in the magnetotransistors accurately. We have measured the Hall voltage in the base region of the fabricated magnetotransistors. The measured values have been compared with the numerical results evaluated from our diffusion model as well as the calculated results from the conventional model. The evaluated Hall voltage from the diffusion model agrees well with the measured values while the sign of the Hall voltage calculated by the conventional model is opposite to that of the measured values in the saturation region. This discrepancy is due to the fact that the diffusion model considers the carrier diffusion while the conventional one does not. The Hall field model including the influence of carrier diffusion may be an important tool to optimize the device structure and to understand the operating principle of the magnetotransistor.

• 한국분말재료학회지
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• 제12권2호
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• pp.131-135
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• 2005

7xxx series Al alloy has the most attractive properties including its excellent high specific strength, stress corrosion cracking and corrosion-resistance. However, in case of the Al-Zn system, the liquid phase has a transient aspect because of the high solid solubility of Zn in Al. Therefore, transient liquid phase sintering behavior was observed during the sintering process. And the amount of liquid and its duration were influenced by the process variables including heating rate and final sintering temperature. At high heating rates($100^{\circ}C/min$), the liquid fraction increased during sintering because diffusion was minimized and therefore local saturation could easily occur. The sintered density increased with increasing heating rate.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
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• pp.38-42
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• 2004

A pilot-scale experiment for the treatment of red tide in the enclosure was done in sea area of Shandong Province, P. R. China on Aug. 25, 2002. With the method of strong dielectric barrier discharge in microgap, $O_2$in air and $H_2O$ in seawater are ionized and dissociated into large numbers of OHㆍradicals, and then dissolved into a part of seawater to form OHㆍsolution of high concentration. With OH' concentration of 0.68mg/L, the kill efficiencies of 29 kinds of red tide organisms such as Chaetoceros lorenzianus and so on reached 99.89%, in which the kill efficiencies of bacterium and vibrio were 100%, and that of Gonyaulax cysts and Prei. Cysts were up to 100%. At the same time, the content of chlorophyll-a was decreased into the lowest limit of test. DO saturation of seawater was greatly increased to 100% because the residual OHㆍradical was decomposed into $H_2O$ and $O_2$after 20 minutes, Therefore the treatment of red tide using OHㆍradicals is a kind of advanced oxidation technology, which realizes zero pollution, zero emission and zero residual in the process of the production of OHㆍradicals and the treatment of red tide.

• Journal of Information Processing Systems
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• 제10권4호
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• pp.589-601
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• 2014

The performance of edge detection often relies on its ability to correctly determine the dissimilarities of connected pixels. For grayscale images, the dissimilarity of two pixels is estimated by a scalar difference of their intensities and for color images, this is done by using the vector difference (color distance) of the three-color components. The Euclidean distance in the RGB color space typically measures a color distance. However, the RGB space is not suitable for edge detection since its color components do not coincide with the information human perception uses to separate objects from backgrounds. In this paper, we propose a novel method for color edge detection by taking advantage of the HSV color space and the Mahalanobis distance. The HSV space models colors in a manner similar to human perception. The Mahalanobis distance independently considers the hue, saturation, and lightness and gives them different degrees of contribution for the measurement of color distances. Therefore, our method is robust against the change of lightness as compared to previous approaches. Furthermore, we will introduce a noise-resistant technique for determining image gradients. Various experiments on simulated and real-world images show that our approach outperforms several existing methods, especially when the images vary in lightness or are corrupted by noise.

• 한국지반환경공학회 논문집
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• 제17권5호
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• pp.5-16
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• 2016

A rainfall induced slope failure is a common natural hazard in mountainous areas worldwide. Sudden and rapid failures which have a high possibility of occurrence in a steep slope are always the most dangerous due to their suddenness and high velocities. Based on a series of experiments this study aimed to determine a critical angle which could be considered as an approximate threshold for a sudden failure. The experiments were performed using 0.42 mm mean grain size sand in a 200 cm long, 60 cm wide and 50 cm deep rectangular flume. A numerical model was created by integrating a 2D seepage flow model and a 2D slope stability analysis model to predict the failure surface and the time of occurrence. The results showed that, the failure mode for the entire material will be sudden for slopes greater than $67^{\circ}$; in contrast the failure mode becomes retrogressive. There is no clear link between the degree of saturation and the mode of failure. The simulation results in considering matric suction showed good matching with the results obtained from experiment. A subsequent discarding of the matric suction effect in calculating safety factors will result in a deeper predicted failure surface and an incorrect predicted time of occurrence.

• International Journal of Air-Conditioning and Refrigeration
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• 제17권3호
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• pp.81-87
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• 2009

The effect of oil on convective boiling of R-123 in an enhanced tube bundle is experimentally investigated at $26.7^{\circ}C$ saturation temperature. The enhanced tube had pores (0.23 mm diameter) and connecting gaps (0.07 mm width), which had been optimized using pure R-123. The effects of oil concentration (0 to 5%), heat flux (10 to $40\;kW/m^2$), mass velocity (8 to $26\;kg/m2^s$) and vapor quality are investigated. The oil significantly reduces the bundle boiling heat transfer coefficient. With 1% oil, the reduction is approximately 35%. Further addition of oil further reduces the heat transfer coefficient. The data are also compared with the pool boiling counterpart. The reduction in the heat transfer coefficient is smaller in a bundle (convective boiling) than in a pool (single-tube pool boiling), with larger difference at a smaller heat flux. Similar to pure R-123 case, the effects of mass velocity and vapor quality are negligible for the convective boiling of R-123/oil mixture.

• 식품과학과 산업
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• 제49권4호
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• pp.19-30
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• 2016

Food industry in Korea is one of the most important manufacturing field since the history of this country. Recent days all industries in the world move to $4^{th}$ industrial revolution beginning from 1st revolution. This means that connections between human to human, human to things and things to things should be settled down. food industry in this country should escape from the conventional manufacturing fields until now and accept new or cutting edge technology NT including artificial intelligence robot system and platform system using Internet of Thing. To overcome the saturation condition of domestic food market, it should be extended our market to overseas. To do this Korean food industry should be reformed the processing system to convergence and fusion inner or multi-disciplinary research in not only research field but also manufacturing field. The food industry must introduce new technology and concept of controlling all manufacturing systems. This paper present the fields should be convergence and the field study together and the new techniques, methods and new products be developed in the future.

• KSBB Journal
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• 제14권3호
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• pp.284-290
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• 1999

우수한 셀룰로오스 생산 균주인 Acetobacter xylinum BRC5의 교반배양에 의한 셀룰로오스 생산성을 향상시키기 위하여 fed-batch 배양을 하였으며, 기질공급속도, 기질 공급량 및 용존 산소의 영향을 검토하였다. 초기 glucose 양을 변화시켜 회분배양하였을 때 glucose 농도가 10 및 20 g/L인 경우 셀룰로오스 생산량은 각각 2.05와 4.10 g/L이였으며 glucose에 대한 셀룰로오스 수율 (Yp/s)은 0.21이었다. 초기 glucose 농도 40g/L일 때 셀룰로오스 수율을 향상시키기 위해서 초기 glucose 농도 20 g/L에서 회분배양을 시작하여 glucose가 gluconic acid로 완전히 전환된 시점부터 추가적으로 glucose를 공급하여 fed-batch 배양기간에 glucose 공급속도는 셀룰로오스 생산성에 큰 영향을 미쳐 20g/L의 glucose를 2.22 g/L.h의 속도로 9시간 첨가하여 fed-batch 배양한 결과 셀룰로오스 생성량이 10 g/L로 가장 우수하여 초기 glucose 농도 20 g/L로 회분배양하였을 때 비하여 약 2배 증가하였으며, $Y_{P/S}$도 0.26으로 현저히 향상되었다. 또한 동일조건으로 fed-batch 배양하면서 glucose 공급량을 증가시켜 40g/L의 glucose를 추가적으로 첨가한 경우 셀룰로오스 생산량은 10.7g/L는 거의 증가되지 않았으며, $Y_{P/S}$가 0.18로 감소하였다. 이는 셀룰로오스 농도가 증가함에 따라 산소 공급이 부족하기 때문이므로 용존산소(DOT)를 2~15% 포화범위에서 조절하여 fed-batch 배양했을 때 DOT를 10% 수준으로 유지하면서 fed-batch 배양기간에 40g/L의 glucose를 추가공급 했을 때 셀룰로오스 생성량은 15.3 g/L로 증가되었고 이때 $Y_{P/S}$는 0.26로 향상되었다. 이는 DO를 제어하지 않는 경우에 비하여 셀룰로오스 생성량이 1.5배 증가한 결과이다.

• 환경영향평가
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• 제28권1호
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• pp.49-62
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• 2019

환경변화는 생물의 성장과 번식 등의 생활사에 영향을 주며, 생물은 살아가는 서식환경에서 생태적 적합도를 가장 극대화 시킬 수 있도록 적응되어 왔다. 본 연구에서는 동적상태의존모델을 이용하여 수온과 용존산소량의 변화가 어류의 초기 성장과 체내 스트레스 누적 과정에 미치는 영향을 분석하였다. 본 연구에서 제시한 어류의 생활사 모델은 취식 행동이 성장과 체내 스트레스 누적에 영향을 받는다고 가정하였다. 또한 수온과 용존산소량의 임계점은 가장 빠른 성장속도를 유도하는 수온과 용존산소량으로 가정하였다. 이에 모델은 수온과 용존산소량의 임계점에서 성장속도가 가장 빨랐으며 임계점보다 크거나 낮은 경우 성장속도는 느렸다. 용존산소량의 저산소 상태는 체내에 누적된 스트레스양의 증가로 성장속도는 느렸고, 고산소 상태는 성장속도를 향상 시켰으나 누적된 스트레스로 신체 크기를 감소시켰다. 본 연구를 통해 환경변화가 생물에 미치는 영향을 예측하는데 있어 단일 또는 독립적인 환경요인 보다 복합적 요인들의 영향이 높음을 보였다. 따라서 환경영향평가에서 환경변화에 대한 영향 예측을 향상시키기 위하여 생리생태학적 측면에서의 복합적 환경 요인을 평가에 도입이 필요하고 또한 관련된 기법 개발에 대한 연구가 후속 되어야 한다.

• 대한토목학회논문집
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• 제33권6호
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• pp.2381-2391
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• 2013

일반적으로 에너지파일의 열적 성능에 영향을 주는 중요한 인자로 지반의 열 물성, 열 교환기 형태, 운용방법, 파일 간 열 간섭 등이 고려될 수 있다. 본 연구에서는 지반의 실제 조건을 반영한 수치모델을 통해 이들 인자들이 미치는 영향을 살펴보았다. 지반의 포화 정도에 따라서 파일의 열 교환율은 최대 3배까지 차이를 보였으며, 열 저항은 최대 8.7%의 차이가 발생하였다. 또한 열 교환기 유형이 파일의 열 성능에 영향을 주며, 3U-Type이 W나 U-Type에 비해 상대적으로 높은 열 효율을 보였다. 운용방법에 있어서, 부분가동 시(8시간 가동, 16시간 휴지) 연속가동에 비해서 약 20%의 열효율을 보전할 수 있으며, 장기적인 열 축적현상을 방지하는데 유리하다. 지반의 조건에 따라 군 말뚝에 의한 열 간섭 정도가 달라지는데, 지반이 포화상태에서 건조 상태로 갈수록 군 말뚝에 의한 열 간섭효과는 감소한다. 일반적인 지반조건에서 열 교환 감소율 1%미만을 유지하는 적정 이격 거리는 U-Type에서 최대 3.2D, W-Type에서 최대 3.6D, 3U-Type에서 최대 3.7D로 산정되었다.