• Journal of Korean Society of Transportation
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• v.19 no.5
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• pp.49-59
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• 2001

In the transportation planning process, origin and destination(O-D) trip matrix is one of the most important elements. There have been developments and applications of the methodology to adjust old matrices using link traffic counts. Commonly, the accuracy of an adjusted O-D matrix depends very much on the reliability of the input data such as the numbers and locations of traffic counting points in the road network. In the real application of the methodology, decisions on the numbers and locations of traffic counting points are one of the difficult problems, because usually as networks become bigger, the numbers of traffic counting points are required more. Therefore, this paper investigates these issues as an experiment using a nationwide network in Korea. We have compared and contrasted the set of link flows assigned by the old and the adjusted O-D matrices with the set of observed link flows. It has been analyzed by increasing the number of the traffic counting points on the experimental road network. As a result of these analyses, we can see an optimal set of the number of counting links through statistical analysis, which are approximately ten percentages of the total link numbers. In addition, the results show that the discrepancies between the old and the adjusted matrices in terms of the trip length frequency distributions and the assigned and the counted link flows are minimized using the optimal set of the counted links.

• Journal of Korean Society of Transportation
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• v.33 no.4
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• pp.393-404
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• 2015

Gravity model has had the major problem that the model explains the characteristics of travel behavior with only deterrence factors such as travel time or cost. In modern society, travel behavior can be affected not only deterrence factors but also zonal characteristics or transportation service. Therefore, those features have to be considered to estimate the future travel demand accurately. In this regard, there are two primary aims of this study: 1. to identify the characteristics of inter-zonal travel, 2. to develop the new type of calibration method. By employing accessibility variable which can explain the manifold pattern of trip, we define the zonal travel behavior newly. Furthermore, we suggest 2-phase calibration method, since existing calibration method cannot find the optimum solution when organizing the deterrence function with the new variables. The new method proceeds with 2 steps; step 1.estimating deterrence parameter, step 2. finding balancing factors. The validation results with RMSE, E-norm, C.R show that this study model explains the inter-zonal travel pattern adequately and estimate the O/D pairs precisely than existing gravity model. Especially, the problem with estimation of short distance trip is overcomed. In conclusion, it is possible to draw the conclusion that this study suggests the possibility of improvement for trip distribution model.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.2
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• pp.31-40
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• 1986

Motor vehicle related air pollution has become more serious because of rapid increase of number of cars, specially in the urban area. The increase trend seems to be accelerated, however, the fact is that road conditions, parking facilities and traffic control systems are far behind coping with this situation. In spite of the lack of related basic data, urban transportation planning (UPT) and air pollution dispersion models were applied to predict air pollution level. In standard UPT model, trip generation, distribution, modal split and network assignment were estimated by experimental equations and appropriate models. The air pollution level in the central business area was believed to be higher and it will increase continuously due to the increase of traffic demand. To meet this situation, air pollution problem should be considered as a part of integrated plannings of urban plans or transportation plans as well as more stringent motor vehicle emission standards, have to be enforced.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.670-672
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• 2005

발전원이 다른 계동으로 연계된 춘천, 남춘천변전소의 태전선로간 Loop 시행시 일부배전선로가 Trip되는 현상에 대하여 PSSE 검토 TOOL을 활용하여 계통을 모의하고 변압기 병렬운전조건에 대한 물리적 의미와 검토대상 배전선로 계통특성, 주변 발전원의 발전력과의 상관관계를 기술검토를 통하여 계통특성을 분석함으로써 Loop시행이 가능한 계통여건을 파악, 선로 운영의 최적방안을 제시하고자 한다.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.171-174
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• 1990

When load areas on a feeder are deenergized due to faults,operaters need to identify nelghboring feeders, try to restore customers and minimize out-of-service areas. These cases include knowledge of system states and various constraints such as voltage drop. This paper concerns the load transfer infault restoration. Also, it is considered the operating constraints such as line current capacity, relay trip current, transformer capacity, voltage drop and line loss. The expert system is able to propose the optimal load transfer method by anallzing system states and considering constraints.

• The Journal of Fisheries Business Administration
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• v.47 no.1
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• pp.21-29
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• 2016

The purpose of this study is to estimate the economic value of skin scuba marine tourism activity in Jeju Island. The economic value is estimated as consumer surplus using count data models including the truncated Poisson model and the truncated negative binominal distribution model. This study collects the effective 369 questionnaires from skin scuba marine tourists through three times in Jeju Island. The truncated Poisson model was statistically more suitable and valid than other models. The truncated Poisson model was applied to estimate consumer surplus as economic value from skin scuba in Jeju Island. A consumer surplus value per trip was estimated as about 4,081,633 won. The annual economic value from skin scuba marine tourism activity was estimated as 8,428,571 won in Jeju Island. Consequently, skin scuba marine tourism activity has a very large economic value in Jeju Island.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.2
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• pp.239-254
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• 1995

Automated Storage/Retrieval (AS/R) systems have been used mostly in manufacturing or distribution industry in order to store or retrieve palletized items automatically. Since the items ore heavy or bulky, only one pallet at a time is moved by the stacker crane In this study, however, we introduce the "multi -load" AS/R system in which the items to be stored are data storage devices of equal size such as video tape or compact disc. Since the items are small and light multiple items can be stored and retrieved in each trip by using a magazine and a robot arm mounted on the crane Given the magazine capacity, and the locations of retrieval items and empty cells in the rack, the throughput of the multi-load AS/R system will depend on the selection of storage locations and the sequence of visits. We propose four heuristic algorithms for the multi-command. Computer simulation is used to evaluate the four algorithms in terms of throughput and number of back tracking of the crane.

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.15-22
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• 2003

In general, the linear regression model has been used to estimate trip generation in the travel demand forecasting procedure. However, the model suffers from several methodological limitations. First, trips as a dependent variable with non-negative integer show discrete distribution but the model assumes that the dependent variable is continuously distributed between -$\infty$ and +$\infty$. Second, the model may produce negative estimates. Third, even if estimated trips are within the valid range, the model offers only forecasted trips without discrete probability distribution of them. To overcome these limitations, a poisson model with a assumption of equidispersion has frequently been used to analyze count data such as trip frequencies. However, if the variance of data is greater than the mean. the poisson model tends to underestimate errors, resulting in unreliable estimates. Using overdispersion test, this study proved that the poisson model is not appropriate and by using Vuong test, zero inflated negative binomial model is optimal. Model reliability was checked by likelihood test and the accuracy of model by Theil inequality coefficient as well. Finally, marginal effect of the change of socio-demographic characteristics of households on trips was analyzed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.9
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• pp.111-119
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• 2008

As the penetration of distributed generation systems is recently high, there have been metering errors, trips of protective devices in KEPCO distribution systems including an occurrence of false fault-indicator in distribution automation system. The cause of malfunctions was the reverse-power-flow phenomenon due to transformer wiring types. By the effect of the reverse-power-flow, each of phase's fundamental currents was added by about 3 times on the neutral line. A new method based on the analysis of the reverse-power-flow is proposed in this paper. Fault currents on each section were analyzed by the proposed method, and the effect of types of transformer wiring was examined experimentally. In order to reduce the malfunctions due to the reverse-power-flow, controlling the zero-sequence impedance of transformer was designed and verified by using PSCAD/EMTDC software.

• Culinary science and hospitality research
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• v.23 no.6
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• pp.27-35
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• 2017

The purpose of this study was to examine the causal relationship among restaurant selection attributes and customer satisfaction and recommendation tastes for young people in their twenties who use tickets for Rail-ro. Data collection was conducted to utilize questionnaire survey with online and offline distribution. The collected data were analyzed using a statistical program SPSS 21.0 with frequency analysis, reliability analysis, factor analysis, and regression analysis. The results of the study showed that Internet search is the most common source of information about restaurants during the trip, and restaurant choice attributes have an important impact on customer satisfaction, food quality, employee service and reputation, but hygiene did not have a big effect on customer satisfaction. In addition, customer satisfaction has a significant effect on recommendation intention. Concluding the results from this study, it investigated the significant attributes for customers selection of restaurants and provide meaningful advice for market managers to make useful marketing strategies to attract more clients and augment economic benefits.