• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.617-624
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• 2011

The two-dimensional sloshing problem in a rigid rectangular tank with a free surface is considered. The flow is generated by a container in harmonic motion in time along the horizontal axis, i.e., a container excited by u=Asin($2{\pi}ft$) where u denotes the container velocity imposed externally, A is the amplitude of the oscillation velocity, and f is the frequency of oscillation. Experimental apparatus is arranged to investigate the large-amplitude sloshing flows in off-resonant conditions, where the large amplitude means that A~O(1), and the distance, S, is comparable to the breadth, L, of the container, i.e., L/S~O(1). Comprehensive particle image velocimetry (PIV) data are obtained, which show that the flow physics of the nonlinear off-resonant sloshing problem can be characterized into three peculiar free surface motions: standing-wave motions similar to those of linear sloshing, a run-up phenomenon along the vertical sidewall at the moment of turn-over of the container, and gradually propagating bore motion from the sidewall to the interior fluid region, like a hydraulic jump.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.86-93
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• 2003

This paper describes that the resonant tank type DC-DC converter consist of reactor and capacitor resonant tank circuit for increased the output current. This circuit configuration is composed of the resonant tank circuit used resonant capacitor and reactor and the capacitor connected in switch are a common using by resonance capacitor and ZVS(Zero Voltage Switching) capacitor. Therefore, the proposed converter can reduce a switching losses, noise, and voltage stress at turn-on and turn-on and has an advantage which is able to operating safely in load short, because DC reactor is connected with resonance reactor in order to supply a fixed current with low ripple from DC power supply. The analysis of proposed circuit uses normalized parameters and characteristic estimation is generally described the proposed circuit with the characteristics of power and output voltage etc. Also, design is based on the characteristic estmations in each step. Hence, We conform a rightfulness theoretical analysis by comparing a theoretical values and experimental values obtained from experiment.

• Journal of Korean Society of Transportation
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• v.16 no.1
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• pp.129-150
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• 1998

신호교차로에서의 효율적인 교통운영을 위해서는 비보호좌회전의 활성화가 필요하며 이를 위해서는 비보호좌회전이 허용되는 신호교차로에서의 교통운영의 정확한 분석이 가능해야한다. 본연구에서는 국내신호교차로에서의 운전자의 행태에 기초하여 USHCM의 비보호 좌회전 분석에서 요구되는 $g_f$, $g_q$, $P_L$, 의 현실적인 값을 산정하기 위한 모형이 제안되었으며 이에 기초하여 비보호좌회전 보정계수 및 용량분석 기법을 제시하였다. 본 연구의 결과는 다음과 같다. 첫째, 공용차로를 가진 비보호좌회전 신호교차로에서 주기당 좌회전교통량(LTC)이 5대까지의 범위에서 G(녹색신호시간)와 LTC를 변수로 한 $g_f$모형이 개발되었다. 둘째, $v_{olc}$와 $qr_o$를 변수로 한 $g_q$모형이 개발되었으며 제안된 모형에 의한 $g_q$값이 진주 및 광주에서의 현장관측치와 거의 일치함을 볼 수 있었다. 셋째, 1994 USHCM의 $P_L$모형이 LTC가 증가할수록 $P_L$값이 감소하는 비현실적인 모형의 구조를 가지므로 현실적인 모형의 구축을 위해 국내 현장자료에 기초하여 LTC를 변수로하여 $P_L$산정을 위한 단순화된 모형이 개발되었다. 넷째, 대향교통류를 통해 좌회전할 수 있는 유효녹색시간의 부분의 $g_u$를 산정하여 비보호좌회전 포화교통류율($S_{LT}$)에 주기 대 $g_u$의 비를 곱한 비보호좌회전 용량산정식이 제안되었다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.2
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• pp.38-45
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• 2000

In this paper, an approach of modeling the optical interconnection system by SPICE simulation is presented. SPICE simulations with equivalent circuit models for optical devices are performed in a stable manner. From the simulated results, eye diagrams for receiver output and BER are obtained. Timing jitter due to laser diode turn-on delay effects can be found under various bias conditions. Using this approach, various system parameters such as bit rate, BER, dissipated transmitter power, and bias conditions can be optimized. It is expected that this approach will find useful applications such as Gigabit Ethernet and ATM.

• Journal of Korean Society of Transportation
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• v.19 no.4
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• pp.85-96
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• 2001

This paper discusses the problem of finding the Origin-Destination(O-D) shortest path in urban road networks that have variable special qualifies such as time windows for passing as well as geometrical special qualities such as U-turn and left-turn prohibition. The focus of this paper is motivated by the problem of finding minimum travel time paths for an advanced traveler information system (ATIS) in the context of intelligent transportation system(ITS) application. The transportation network with variable and geometrical special qualities is a more realistic representation of the urban road network in the real word. But, the traditional and existing shortest path algorithms can not search practical shortest path that variable special quality is reflected. This paper presents a shortest path algorithm which can search reasonable shortest path information for the urban ATIS application within a real time. The algorithm is based on genetic algorithm(GA). The high performance of the proposed algorithm is demonstrated by computer simulations.

• Journal of Korean Society of Transportation
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• v.26 no.1
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• pp.145-153
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• 2008

Existing shortest-path algorithms mainly consider a single attribute. But traveler actually chooses a route considering not single attribute but various attributes which are synthesized travel time, route length, personal preference, etc. Therefore, to search the optimal path, these attributes are considered synthetically. In this study route searching algorithm which selects the maximum utility route using discrete choice model has developed in order to consider various attributes. Six elements which affect route choice are chosen for the route choice model and parameters of the models are estimated using survey data. A multinomial logit models are developed to design the function of route choice model. As a result, the model which has route length, delay time, the number of turning as parameter is selected based on the significance test. We use existing shortest path algorithm, which can reflect urban transportation network such as u-turn or p-turn, and apply it to the real network.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.3
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• pp.35-42
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• 2012

The database for driving patterns can be utilized in various system such as automatic driving system, driver safety system, and it can be helpful to monitor driving style. Therefore, we propose a driving pattern recognition system in which the sensor streams from a smartphone are recorded and used for recognizing driving events. In this paper we focus on the driving pattern recognition that is an essential and preliminary step of driving style recognition. We divide input sensor streams into 7 driving patterns such as, Left-turn(L), U-turn(U), Right-turn(R), Rapid-Braking(RB), Quick-Start(QS), Rapid-Acceleration (RA), Speed-Bump(SB). To classify driving patterns, first, a preprocessing step for data smoothing is followed by an event detection step. Last the detected events are classified by DTW(Dynamic Time Warping) algorithm. For assisting drivers we provide the classified pattern with the corresponding video stream which is recorded with its sensor stream. The proposed system will play an essential role in the safety driving system or driving monitoring system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.561-564
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• 2007

In driving a car, u-turn or left turn makes the speed of car decrease considerably or require more waiting time at the cross for the traffic signal to turn green. A more straight path, therefore, is probably faster to arrive at the destination than zig-zaged path with same distance. Previous works related to the path navigation do not consider the straightness of the path. In this paper, we have proposed the path navigation algorithm with turn heuristic for enhancing the straightness of a path. We have implement the proposed algorithm and compared it with a traditional $A^*$ algorithm. The experimental result shows that the degree of the straightness of a path is enhanced by 30% and the navigation distance of a path is deceased by 3.3%.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2072-2077
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• 2007

In driving a car, u-turn or left turn makes the speed of car decrease considerably or require more waiting time at the cross for the traffic signal to turn green. A more straight path, therefore, is probably fester to arrive at the destination than zig-zaged path with same distance. Previous works related to the path navigation do not consider the straightness of the path. In this paper, we have proposed the path navigation algorithm with turn heuristic for enhancing the straightness of a path. We have implement the proposed algorithm and compared it with a traditional $A^*$ algorithm. The experimental result shows that the degree of the straightness of a path is enhanced by 30% and the navigation distance of a path is deceased by 3.3%.

• Journal of the Korean association of regional geographers
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• v.21 no.2
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• pp.207-225
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• 2015

This study attempts to explore settlement and adaptation status involved in differing urban-to-rural migration types in Gyeongbuk Province and suggests policy implications based on this analysis. The attributes of urban-to-rural migrants in Gyeongbuk Province differ spatio-temporally, and their status of settlement and adaptation is also different depending on urban-to-rural migration types. "U-turn" migrants who are mostly first-generation rural-to-urban migrants with experience in farming and rural community life engage primarily in crop agriculture. "J-turns" and "I-turns," who have no experience in farming or rural community life, migrated for idyllic rural life. The household income of these types is relatively low compared to U-turn type. U-turns' degree of adaptation is relatively lower than the other types, and U-turn migrants mainly rely on family and community assets in order to solve problems. J-turns' and I-turns' degree of satisfaction is relatively high. However they typically have substantial difficulties in adapting due to lack of pre-migration preparation. Policy implications are : 'switching away from general and inclusive policies of support,' 'transition to policies embedded in the attributes of regions and migration types,' 'improvement of policy governance,' 'enhancement of support for pre-migration preparation and customized support based on the needs of migrants,' and 'comprehensive improvements of settlement environment to better integrate migrants with current residents.'.