• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.67-72
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• 2002

Water content of soils within pavement varies seasonally depending on climatic factors such as rainfall, temperature and so on, since a hydraulic gradient due to rainfall causes moisture flow, and a thermal gradient due to temperature change induces not only heat flow but also moisture flow directly and indirectly. Soils within pavement are usually in an unsaturated state, and heat flow and moisture flow have been recognized as coupled processes with complex interactions between them. This paper presents a one-dimensional analysis model by the finite element method for the coupled heat flow and moisture flow in unsaturated soils. The model can be used to predict not only the change of temperature and water content, but also frist heave with time. It will be a meaningful work for the design and maintenance of pavement to predict the change of the temperature and water content and frist heave. The model is tested through comparisons with the results by other models.

• The Journal of the Acoustical Society of Korea
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• v.15 no.5
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• pp.44-52
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• 1996

Acoustical characteristics of internal pipe structures and a loudspeaker of the thermoacoustic refrigerator are analyzed by using the transfer matrix method. The resonator system is dismantled into verious basic acoustic elements, and then linearized transfer matrices are serially combined with the dynamical system of linearized loudspeaker model, that the total system of thermoacoustic refrigerator can be analyzed in terms of frequency characteristics and acoustic field shape. Additionally, by using equations for energy flow through the capillary stack, the temperature distribution over the stack is numerically estimated. After expressing the acoustic work flow, thermoacoustic flow, and energy loss per unit length in a single capillary duct by using the transverse functional variations, overall energy flow rate and energy balance are obtained for the whole capillary stack. The final expression for energy flow through the stack is numerically evaluated by varying physical parameters obtained from the sound field analysis. After confirming good agreements between predicted and experimental results for the interior sound field of a refrigerator model, the thermoacoustic characteristics of Hofler's apparatus is analyzed by the proposed method and it is observed that the results agree well with Hofler's experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7B
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• pp.1253-1259
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• 2000

적합성 시험은 프로토콜 구현물인 IUT(Implementation Under Test)가 프로토콜 규격과 일치하는지를 검증하는 것으로, 이 적합성 시험의 질은 생성된 시험열에 의존한다. 기존에는 시험열 생성이 수작업으로 이루어지기 때문에 오류의 가능성을 내포한다. 본 논문에서는 자동화된 툴(tool)인 Design/CPN을 이용하여 SDL(Specification and Description Language)로 기술된 프로토콜의 시험열을 생성한다. SDL로 기술된 프로토콜을 자료흐름을 고려한 CPN(Colored Petri Nets)으로 변환 후 Design/CPN에 입력하여 자동 생성된 OG(Occurrence Graph)와 디스크립터 (descriptor)로부터 시험열을 생성함으로써, 기존의 시험열 생성 방법에 비해 오류 가능성을 줄일 수 있으며, 자료 흐름이 고려된 시험열을 얻을 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1434-1440
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• 2008

Performance of TCP/IP is studied on the wireless network using flow control and congestion control mechanism based on transmission rate. We discuss the elimination or the reduction of various phenomena of burst by flow controlling on transmission rate and verify that there are TCP ACK compression promblems on the queue by burst reaction while executing transmission rate controlled channels. Analyzing periodic burst reaction on the queue of source IP, the maximum value of queue is expected, which represents the applible expectation of throughput reduce and shows the improvement of performance by the reduce of throughput due to hi-directional traffic.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.7-9
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• 2020

기존 CCTV 비디오에서 딥러닝 기반의 이상 탐지 연구는 객체의 행동 값만을 이용하여 이상을 탐지하였기 때문에, 시간 흐름에 따른 정보가 축소되는 문제점이 있었다. 그러나 CCTV 비디오에서의 이상의 원인은 다양한 요소와 시계열 분석에 따른 정보로 이루어져 있어 시간 정보를 유지하면서 다양한 특징 값을 사용한 모델을 설계할 필요가 있다. 따라서 본 논문에서는 C3D에 광학 흐름을 결합한 새로운 앙상블 모델을 제안한다. 실험 결과 본 논문에서 제안하는 모델이 75.83의 AUC를 얻어 기존에 연구되었던 행동 값만을 사용한 모델보다 높은 정확도를 달성하였다. 또한 이상 탐지 모델 설계 시 객체의 행동에 다양한 측면을 고려할 수 있는 여러 특징 값과 시계열 분석에 따른 정보를 사용하는 것이 적절하다는 결론을 도출하였다.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.4
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• pp.179-188
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• 2017

It is very challenging to analyze the traffic flow in the city because there are lots of traffic accidents, intersections, and pedestrians etc. Now, even in mid-size cities Bus Information Systems(BIS) have been deployed, which have offered the forecast of arriving times at the stations to passengers. BIS also provides more informations such as the current locations, departure-arrival times of buses. In this paper, we perform the time-series analysis of the traffic flow using the data of the average trvel time and the average speed between stations extracted from the BIS. In the mid size cities, the data from BIS will have a important role on prediction and analysis of the traffic flow. We used the Dynamic Linear Model(DLM) for how to make the time series forecasting model to analyze and predict the average speeds at the given locations, which seem to show the representative of traffics in the city. Especially, we analysis travel times for weekdays and weekends separately. We think this study can help forecast the traffic jams, congestion areas and more accurate arrival times of buses.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1997.11a
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• pp.229-234
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• 1997

밀폐공간내에서 일어나는 자연대류 열전달은 태양열 집열판, 연료탱크, 원자로의 핵반응로, 초전도 자성체의 냉각 및 건물이나 방의 효율적인 열설계, 화재시의 안전대책등 공업적으로 그 응용성이 매우 광범위하고 다양하게 생활주변에서 흔히 볼 수 있다. 밀폐공간내에 경계층 유동이 존재할 경우, 이 경계층 흐름은 일반적으로 외부유동에서의 경계층 유동과는 달리 코어영역(Core region)에서의 흐름과 서로 밀접한 관계가 있다. (중략)

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.161-164
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• 2001

정상상태에서 소자 내부의 격자온도 분포를 해석할 수 있는 시뮬레이터를 제작하였다. Slotboom 변수를 사용하여 열흐름 방정식을 이산화하였다. 또한 격자온도 분포를 고려한 초기 해의 설정 방법을 제안하였다. 제안된 방법의 타당성을 검증하기 위하여 N/sup ＋ P 정합 다이오드에 대해 모의실험을 수행하여 MEDICI의 결과와 비교하였다 순방향 전압-전류 특성은 MEDICI의 결과와 비교하여 7% 이내의 최대 상대오차를 보였고 전위 분포와 온도 분포는 각각 2%, 2% 이내의 최대 상대오차를 보였다. BANDIS에서는 수렴을 위해 평균 3.7회 이하의 행렬 연산이 필요하였으며, MEDICI에서는 평균 5.1회 이하의 행렬 연산이 필요하였다.

• Journal of Bio-Environment Control
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• v.12 no.3
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• pp.107-113
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• 2003

This study was carried out to improve the performance of pre-developed heat recovery devices attached to exhaust-gas flue connected to combustion chamber of greenhouse heating system. Four different units were compared in the aspect of heat recovery performance; A-, B-, and C-types are exactly the same with the old ones reported in previous studies. D-type newly developed in this experiment is mainly different with the old ones in its heat exchange area and tube thickness. But airflow direction(U-turn) and pipe arrangement are similar with previous three types. The results are summarized as follows; 1. System performances in the aspect of heat recovery efficiency were estimated as 42.2% for A-type, 40.6% for B-type, 54.4% for C-type, and 69.2% for D-type. 2. There was not significant improvement of heat recovering efficiency between two different airflow directions inside the heat exchange system. But considering current technical conditions, straight air flow pattern has more advantage than hair-pin How pattern (U-turn f1ow). 3. The main factors influencing on heat recovery efficiency were presumably verified to be the total area of heat exchange surface, the thickness of ail-flow pipes, and the convective heat transfer coefficient influenced by airflow velocity under the conditions of allowable pipe durability and safety. 4. Desirable blower capacity for each type of heat recovery units were significantly different to each other. Therefore, the optimum airflow capacity should be determined by considering in economic aspect of electricity required together with the optimum heat recovery performance of given heat recovery systems.

• Journal of Korea Fair Competition Federation
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• no.79
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• pp.38-42
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• 2002