• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.3
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• pp.50-58
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• 2017

TPCLT(Twice Per Cycle Left-turn) operation reduces this left-turn 'spill-over' problem on an as needed basis by servicing the protected left-turn movement as a leading and a lagging left-turn. In this study, to evaluate the effectiveness of TPCLT applied to three-legged signalized intersection in Korea, the analysis was carried out using VISSIM and SSAM model analysis. The study was implemented by three cases which are TPCLT operation, non-TPCLT operation and half-cycle operation using VISSIM program. According to the 9-left-turn volume scenario, total delay and travel times of each case was analyzed by VISSIM program. The study result shows more effective applying TPCLT operaion in the present ~ +50% scenario area at the intersection in terms of total delay.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.1-9
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• 2006

Recently, there has been an interest in premixed diesel engines as it has the potential of achieving a more homogeneous and leaner mixture close to TDC compared to conventional diesel engines. Because this concept reduced NOx and smoke emissions simultaneously. Early studies are shown that in a HCCI(Homogeneous Charge Compression Ignition) engine, the fuel injection timing and intake air temperature affect the mixture formation. The purpose of this study is to investigate characteristics of combustion and mixture formation according to injection timing and intake air temperature in a common rail direct injection type HCCI engine using an early injection method called the PCCI(Premixed Charge Compression Ignition). From this study, we found that the fuel injection timing and intake air temperature affect the mixture formation and in turn affects combustion in the PCCI engine.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.43-53
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• 2007

We have analyzed low current operation characteristics of a VCSEL transmitter operating at fixed Current over wide temperature range. Used 850 nm oxide VCSEL has low temperature dependence of the threshold current and $d^2I_{th}/dT^2$ is approximately $1.346\times10^{-4}mA/^{\circ}C^2$. We fixed on-current so that output power from the chip is 1 mW at $20^{\circ}C$ and investigated the turn-on, turn-off characteristics and eye-diagram of the 850 nm oxide VCSEL transmitter with varying ambient temperature and off-current. We measured rise time, fall time, extinction ratio and timing jitter by changing tile ambient temperature and off-current. With the fixed off-current of around $0.1\sim0.2mA$ lower than the lowest threshold current the transmitter successfully operated at 1.25 Gbps over a wide temperature range from $-20^{\circ}C$ to $80^{\circ}C$.

• Proceedings of the KOR-KST Conference
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• 1995.02a
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• pp.3-32
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• 1995

The Highway Capacity Manual specifies procedures for evaluating intersection performance in terms of delay per vehicle. What is lacking in the current methodology is a comparable quantitative procedure for ass~ssing the safety-based level of service provided to motorists. The objective of the research described herein was to develop a computational procedure for evaluating the safety-based level of service of signalized intersections based on the relative hazard of alternative intersection designs and signal timing plans. Conflict opportunity models were developed for those crossing, diverging, and stopping maneuvers which are associated with left-turn and rear-end accidents. Safety¬based level-of-service criteria were then developed based on the distribution of conflict opportunities computed from the developed models. A case study evaluation of the level of service analysis methodology revealed that the developed safety-based criteria were not as sensitive to changes in prevailing traffic, roadway, and signal timing conditions as the traditional delay-based measure. However, the methodology did permit a quantitative assessment of the trade-off between delay reduction and safety improvement. The Highway Capacity Manual (HCM) specifies procedures for evaluating intersection performance in terms of a wide variety of prevailing conditions such as traffic composition, intersection geometry, traffic volumes, and signal timing (1). At the present time, however, performance is only measured in terms of delay per vehicle. This is a parameter which is widely accepted as a meaningful and useful indicator of the efficiency with which an intersection is serving traffic needs. What is lacking in the current methodology is a comparable quantitative procedure for assessing the safety-based level of service provided to motorists. For example, it is well¬known that the change from permissive to protected left-turn phasing can reduce left-turn accident frequency. However, the HCM only permits a quantitative assessment of the impact of this alternative phasing arrangement on vehicle delay. It is left to the engineer or planner to subjectively judge the level of safety benefits, and to evaluate the trade-off between the efficiency and safety consequences of the alternative phasing plans. Numerous examples of other geometric design and signal timing improvements could also be given. At present, the principal methods available to the practitioner for evaluating the relative safety at signalized intersections are: a) the application of engineering judgement, b) accident analyses, and c) traffic conflicts analysis. Reliance on engineering judgement has obvious limitations, especially when placed in the context of the elaborate HCM procedures for calculating delay. Accident analyses generally require some type of before-after comparison, either for the case study intersection or for a large set of similar intersections. In e.ither situation, there are problems associated with compensating for regression-to-the-mean phenomena (2), as well as obtaining an adequate sample size. Research has also pointed to potential bias caused by the way in which exposure to accidents is measured (3, 4). Because of the problems associated with traditional accident analyses, some have promoted the use of tqe traffic conflicts technique (5). However, this procedure also has shortcomings in that it.requires extensive field data collection and trained observers to identify the different types of conflicts occurring in the field. The objective of the research described herein was to develop a computational procedure for evaluating the safety-based level of service of signalized intersections that would be compatible and consistent with that presently found in the HCM for evaluating efficiency-based level of service as measured by delay per vehicle (6). The intent was not to develop a new set of accident prediction models, but to design a methodology to quantitatively predict the relative hazard of alternative intersection designs and signal timing plans.

• 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.27 no.5
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• pp.17-28
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• 2009

There are many limitations in dealing with rapidly changing traffic demand in urban cities. Thus recently, traffic operation and management skills are more emphasized rather than the expansion of traffic facilities. In particular, in the interrupted flow formed by signalized intersections, it is quite important to give optimal signal timing to each intersection with consideration of progression. However, as fixed signal times per direction can affect passing capacity in signalized intersections, the present four-signal phase including a left-turn signal has many limitations, including reduction of directional road capacity when traffic demand is increases dramatically during peak hours. Because of this problem, lots of studies about internal metering techniques for oversaturated signal control skills have progressed but these techniques are not used widely due to the absence of detectors for queue sensing in real-time signal control systems. In this research, a new methodology called the "restrictive left-turn signal control", which is already used at the intersection above Samsung subway station, is suggested in order to reduce control delay of urban arterial roads. The restrictive left-turn signal control allows a driver to make a U-turn and then a right turn instead of turning left in that intersection. With this change, the restrictive left-turn signal control can contribute to increased intersection capacity by reducing the number of signal phases and maximizing the through phase time. However, road structure and traffic conditions at the target intersections should be considered before the adoption of the proposed signal control.

• Journal of Power Electronics
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• v.6 no.3
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• pp.253-263
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• 2006

A high performance and low cost single switch current fed energy recovery circuit (ERC) for an alternating current (AC) plasma display panel (PDP) is proposed. Since it is composed of only one power switch compared with the conventional circuit consisting of four power switches and two large energy recovery capacitors, the ERC features a simpler structure and lower cost. Furthermore, since all power switches can be switched under soft switching operating conditions, the proposed circuit has desirable merits such as increased reliability and low switching loss. Specifically, there are no serious voltage notches across the PDP with the aid of gas discharge current compensation, which can greatly reduce the current stress of all inverter switches, and provide those switches with the turn on timing margin. To confirm the validity of proposed circuit, its operation and performance were verified on a prototype for 7-inch test PDP.

• Korean Journal of Poultry Science
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• v.7 no.1
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• pp.13-22
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• 1980

On the Chicago Meracntile Exchange, individuals and firms buy and sell contracts for specified amounts of products that are to be delivered at a time period in the future at a price arrived at through openly competitive bidding. The transfer of ownership of these delivery promises takes place in a particular trading pit, for each commodity, on the floor of the Exchange. Trades are officially made by qualified members of the Exchange who act as brokers for their customers. For his services, the broker is paid a nominal round- turn commission fee by the customer. Although each commodity contract carefully describes the particular standards that product must meet in order to be a acceptable for delivery, actually fewer than three percent of the contracts traded are consummated by delivery. For the most part, contract obligations ions art offset, and thereby liquids. before the termination of the delivery month. The trader liquidates his position in the market after analyzing price trends, his timing, and his calculated price objectives. (omitted)

• Tribology and Lubricants
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• v.14 no.2
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• pp.63-74
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• 1998

The damage of cam/tappet surface is one of the major reasons for energy loss in an I.C. engine. High friction causes the accelerated wear of the cam/tappet surfaces which in turn changes the valve opening/closing timing. During the accelerated test evidence of both rolling fatigue and sliding abrasive wear could be found. Based on the results of the accelerated test, a scheme was devised to decrease tappet wear. Wear reduction of the tappet was achieved by using undulated surface topography in the tappet center region. The wear reduction is achieved by trapping of the wear particles in the undulations as well as by increasing the supply of lubricant to the sliding interface.

• Journal of Auto-vehicle Safety Association
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• v.9 no.2
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• pp.26-32
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• 2017

This paper presents the lateral stability criteria for integrated chassis control. To determine the intervention timing of chassis control system, the lateral stability criteria is needed. The proposed lateral stability criteria is based on velocity-yawrate gain domain to determine whether vehicle is stable. If the yawrate gain violates the proposed criteria, the stability of the vehicle is considered as unstable. Characteristic velocity and critical velocity are employed to distinguish lateral stability criteria. The inside of the two boundaries is stable and the outside is unstable. If yawrate gain of vehicle violates the lateral stability criteria, the chassis control begin to intervene. To validate the lateral stability criteria, both computer simulations and vehicle test are conducted with respect to circular turn scenario. The proposed lateral stability criteria makes it possible to reduce intervention of chassis control system.