• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2265-2272
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• 2004

The aquaculture tank is used for breeding fish in sea water which was pumped up to land. The flow characteristics in the aquaculture were investigated with varying the tank geometry and flow rate. The numerical analysis has been employed for calculating the velocity and temperature distributions in a water tank of rectangular type. The finite volume method and SIMPLE algorithm with 3-dimensional standard $\kappa$-$\varepsilon$ turbulence model were used for the numerical analysis. For comparison with experimental results, the PIV system was applied to visualize the flow patterns quantitatively. The numerical results showed good agreements with the experimental results. The mean velocity and temperature versus aquarium depth were represented for various circulating flow rates. Especially, the aquaculture environment is recommended that the aquarium depth has to be d=0.5 m, and this case is the condition of higher velocity and temperature in winter season.

• Ocean and Polar Research
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• v.34 no.2
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• pp.265-273
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• 2012

A new algorithm was developed, not only to detect the existence of a thermocline, but also to extract the thermocline parameters (such as thermocline thickness, mixed layer thickness, maximum temperature gradient, and temperature difference of thermocline), using the vertical profile of water temperature. According to Kappa analysis, in order to find adequate threshold values of vertical water temperature gradients ${\Delta}T$ ($^{\circ}C/m$), agreement and reliability were 87% and 0.74 respectively, in the conditions of maximum ${\Delta}T{\geq}0.5$ and surface and bottom layers ${\Delta}T<{\mid}0.2{\mid}$. Also, three different kinds of methods, viz. 1. Gradient method, 2. Hyperbolic tangent method, and 3. Differential hyperbolic tangent method, were tested to extract the key parameters of a thermocline. Comparing the results of three different methods, the differential hyperbolic tangent method was the most appropriate to extract the start and end point of a thermocline curve.

• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.68-74
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• 1997

One hundred and eighty two lactic acid bacteria, isolated mainly from kimchi, including reference strains were examined for their ability to utilize 95 carbon sources. The test strains were assigned to 5 major, 1 minor and 12 single-membered clusters based on the $S_{SM}$, UPGMA algorithm (at similarity of $80{\%}$). These aggregate clusters were equivalent to the genus Leuconostoc (aggregate cluster M and N), the genus Lactobacillus (aggregate cluster Q and R), and the genera Lactobacillus and Leuconostoc (aggregate cluster O and P) according to the database of the Biolog system. This study demonstrates that rapid identification and classification of isolates originating from kimchi can be achieved on the basis of such carbon source utilization tests.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.673-679
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• 2000

LNG Carriers are currently known as sole commercial means of shipping natural gas on the sea. They are designed to proven dangerous explosion for shipping a lot of gas over long distance. In this study. In this study, a scaled model chamber was made to investigate ventilation characteristics of the hood room in LNG carrier. Experimental study was performed in model using visualization equipments with laser apparatus and image intensifier CCD camera gated by an AOM controller Twelve different kinds of measuring area were selected as experimental condition. Instant simultaneous velocity vectors at whole field were measured by using 2-D PIV system which software adopts two-frame grey-level cross correlation algorithm. To look into stagnation area of hood room for LNG carrier, a three-dimensional numerical simulation with standard ${\kappa}-{\varepsilon}$ model was carried out by using PHOENICS for three kinds of Reynolds number, $6.5{\times}10^3$, $9.7{\times}10^3\;and\;1.29{\times}10^4$, based on the cavity inlet velocity and cavity height. The flow pattern showed the large scale counter-clockwise forced-vortex rotated at center area, small eddies at each corner and stagnation area located at left-back upper side of model.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.803-806
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• 2003

This paper presents a detailed study of the extended Kalman filter for estimating the rotor speed of an IM drive. The general structure of the Kalman filter is reviewed and the various system vectors and matrices are defined. By including the rotor speed as a state variable, the EKF equations are established from a discrete two axis model of the three-phase induction motor using the software MATLAB/Simulink, simulation of the EKF speed estimation algorithm is carried out for an induction motor drive with direct self control. The investigations show that the EKF is capable of tracking the actual rotor speed provided that the elements of the covariance matrices are properly selected.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1012-1016
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• 1998

According to the adoption of inverter circuit topology for welding machine area, the improvement of welding performance can be achieved. However conventional CO2 inverter arc welding machine uses the constant voltage characteristics. So the metal transfer is performed under unoptimum condition in the sence of spatter generation. In this paper the new control algorithm is proposed for welding machine, which is the instantaneous output current control method using single chip microprocessor. But the optimum waveform of welding current is still uncertain, as a first step for figuring out the optimized waveforms, this study was performed. And as a result of performance test of the proposed system, it was demonstrated that all of the waveform variation parameter could be set individually and the generated spatter is reduced compared to conventional inverter arc welding machine.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.632-635
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• 2016

증강현실에서 영상과 증강된 콘텐츠 간의 이질감을 줄이기 위해서 정확한 호모그래피 행렬을 추정해야 하며, 정확한 호모그래피 행렬을 추정할때 RANSAC 알고리즘이 널리 사용된다. 그러나 RANSAC 알고리즘은 랜덤 샘플링 과정을 반복적으로 거치기 때문에 불필요한 연산 과정이 발생하고 이로 인해 알고리즘의 효율이 저하된다. 이러한 단점을 극복하기 위해 DCS-RANSAC 알고리즘이 제안되었다. 제안된 DCS-RANSAC 알고리즘은 이미지를 특징점 분포 패턴에 따라 그룹으로 분류하고 각 그룹에 제약조건 문제를 적용하여 불필요한 연산 과정을 줄이고 정확도를 향상시킨 알고리즘이다. 그러나 DCS-RANSAC 알고리즘에서 사용된 이미지 그룹 데이터는 수동적인 방법을 통해 직관적으로 분류되어 있지만 특징점 분포 패턴이 다양하지 않아 분류시 정확도가 저하되는 경우가 있다. 위의 문제점을 해결하기 위해 본 논문에서는 머신러닝 기법을 통해 이미지들을 자동으로 분류하고 각 그룹마다 각기 다른 제약조건을 적용하는 MCS-RANSAC 알고리즘을 제안한다. 제안하는 알고리즘은 머신러닝 기법을 사용하여 전처리 단계에서 이미지를 분류하고 분류된 이미지에 제약조건을 적용시켜 알고리즘의 처리시간을 줄이고 정확도를 향상시켰다. 실험 결과 본 논문에서 제안하는 MCS-RANSAC은 DCS-RANSAC 알고리즘에 비해 수행시간이 약 6% 단축되었고 호모그래피 오차율은 약 15% 줄어들었으며 참정보 비율은 2.8% 증가한 것으로 확인되었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.348-351
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• 2016

대학에서는 매학기 개설된 수업에 대해 강의실 배정작업을 진행하고 있으며 대부분의 대학에서는 년4회(1 2학기, 여름, 겨울 계절학기) 수작업으로 반복적인 강의실 배정 작업을 수행하고 있다. 강의실 배정작업은 교수가 선호하는 강의실 또는 교과목특성(실험과목 및 대형 강의)이 반영된 강의실 등 다양한 조건에 의해 강의실을 배정하고 있으며 수작업으로 일일이 강의실을 배정 하는 데에는 상당한 시간이 소요되고 있다. 몇몇 대학에서는 강의실 배정작업을 개선하기 위해 교수 및 강의실의 특성을 고려한 강의실 자동 배정 시스템을 구축을 시도 하였으나, 많은 변수로 인해 여전히 수작업으로 강의실을 배정하고 있다. 이에 본 연구에서는 강의실 자동 배정 시스템을 구축하기 위한 방법으로 최근 3년간 기 배정된 강의실 빅 데이터 자료를 기반으로 작성된 강의실 자동 배정 알고리즘을 제시하고 실적용한 고려대학교 시스템 구축 사례를 살펴보고자 한다.

• Journal of Power Electronics
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• v.11 no.4
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• pp.490-498
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• 2011

This paper presents a novel analysis, design, and implementation of a battery charging three-phase high frequency semi-controlled power converter feasible for plug-in hybrid electric vehicles. The main advantages of the proposed topology include high efficiency; due to lower power losses and reduced number of switching elements, high output power density realization, and reduced passive component ratings proportionally to the frequency. Additional advantages also include grid economic utilization by insuring unity power factor operation under different possible conditions and robustness since short-circuit through a leg is not possible. A high but acceptable total harmonic distortion of the generator currents is introduced in the proposed topology which can be viewed as a minor disadvantage when compared to traditional boost rectifiers. A hysteresis control algorithm is proposed to achieve lower current harmonic distortion for the rectifier operation. The rectifier topology concept, the principle of operation, and control scheme are presented. Additionally, a dc-dc converter is also employed in the rectifier-battery connection. Test results on 50-kHz power converter system are presented and discussed to confirm the effectiveness of the proposed topology for PHEV applications.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.50-53
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• 2016

Image processing techniques play an increasingly important role in many aspects of our daily life. For example, it has been shown to improve agricultural productivity in a number of ways such as plant pest detecting or fruit grading. However, massive quantities of images generated in real-time through multi-devices such as remote sensors during monitoring plant growth lead to the challenges of big data. Meanwhile, most current image processing systems are designed for small-scale and local computation, and they do not scale well to handle big data problems with their large requirements for computational resources and storage. In this paper, we have proposed an IPABigData (Image Processing Algorithm BigData) platform which provides algorithms to support large-scale image processing in agriculture based on Hadoop framework. Hadoop provides a parallel computation model MapReduce and Hadoop distributed file system (HDFS) module. It can also handle parallel pipelines, which are frequently used in image processing. In our experiment, we show that our platform outperforms traditional system in a scenario of image segmentation.