• Journal of Korea Port Economic Association
• /
• v.26 no.3
• /
• pp.42-55
• /
• 2010

This paper primarily deals with a decision-making for determining the number of voyages in each ship size under a specific port structure in order to minimize the total transport cost consisting of transport cost at sea, queuing cost in port, and inventory cost in yard. As a result of computer simulation using queuing model characterized by inter-arrival time distribution, we were able to find out some combination of voyage numbers of 3 ship-size(50,000-ton, 100,000-ton, and 200,000-ton), where the total transport cost can be minimized under a specific port structure. The simulation model also allows us to figure out any trade-off relationship among sea transport cost, queuing cost in port, and inventory cost in yard. Put it differently, an attempt to reduce the sea transport cost by increasing the number of voyages of the largest ship size, the transport cost incurred in both port and yard is hypothesized to be increased and vice versa. Consequently, Port managers are required to adjust the number of annual number of voyages allocated in each ship size, put into the sea lines for importing raw materials, in order to optimize the transport costs incurred under the specific port system. We may consider a net present value(NPV) model for performing an economic feasibility analysis on port investment project. If a total discounted net benefit, including cost savings, exceeds the initial investment for an additional berth construction, then we accept the port investment project. Otherwise, we reject the proposed port investment plan.

• Journal of Korean Society of Transportation
• /
• v.19 no.3
• /
• pp.61-73
• /
• 2001

The purpose of this study is to simulate the suitable space of parking lots for Mass traffic instigating facilities in Pusan. After the suitable scale of parking lots estimate using GPSS, one of the Queue Simulation, with the average arriving time and the average parking time at parking lots, the formula is simulated by the Regression model to relate a total floor area and the suitable number of parking lots. The improved criteria or present parking lots is needed to prevent the unnecessary vehicles and improve the efficiency of land use. The suitable scale of parking lots estimate just with the state of using the parking lots in this study. but it is necessary to consider land use, traffic condition, commercial area etc.

• Journal of Korean Society of Transportation
• /
• v.26 no.1
• /
• pp.203-213
• /
• 2008

U-Turn offers convenience to drivers. U-Turn increases efficiency of traffic flow. But Standard of U-Turn is not clear. It caused many problems of traffic flow and traffic safety. This study estimate length between U-Turn location with front intersection based on stopping sight distance and left-turn vehicle's queue length. Variables are used traffic volume and operation speed. This study Analysis of U-Turn vehicle's behaviors and classification of conflict form by investigation. U-Turn length estimating based on relationship analysis between conflict with U-Turn length. Variables are used lane changing angles and operation speed. This study estimates length between U-Turn location with back intersection based on gap acceptance theory. Variables are used traffic volume, operation speed and lane changing angles. So, U-Turn location and length estimated considering traffic flow and traffic safety.

• Journal of Korean Society of Transportation
• /
• v.24 no.5 s.91
• /
• pp.77-88
• /
• 2006

The purpose of this study is to Propose the time dependent K-least time path algorithm applicable to a real-time based operation strategy in multi-modal transportation network. For this purpose, we developed the extended method based on entire path deletion method which was used in the static K-least time path algorithm. This method was applied to time dependent K-least time path algorithm to find k least time paths in order based on both time dependant mode-link travel time and transfer cost In particular, this algorithm find the optimal solution, easily describing transfer behavior, such as walking and waiting for transfer by applying a link-based time dependent label. Finally, we examined the verification and application of the Proposed algorithm through case study.

• Journal of Korean Society of Transportation
• /
• v.25 no.1 s.94
• /
• pp.133-141
• /
• 2007

The study examines households' auto ownership and car type choice with a nested legit model. In summary. ${\rho}^2$ and the inclusive values, which represent the goodness of fit of the model, are statistically significant. Therefore. the nested logit model is superior to the standard legit model in this case. Also. the elasticity of operating costs is larger than 1, which means households' car ownership and car type choice is very sensitive to the operating costs. Finally, the elasticity of the operating costs in the lower income group is higher than that or the operating costs in the higher income group.

• Journal of Korea Port Economic Association
• /
• v.29 no.3
• /
• pp.159-174
• /
• 2013

This paper mainly deals with the appropriation of ship voyage allocation, using a heuristic regression model, in order to reduce total costs incurred in port, yard and at sea under the specific port condition. Because of different behavior of costs incurred in port, yard and at sea, an effort to minimize these costs by adjusting the number of voyages for three ship classes(50,000, 100,000, and 150,000-ton) should be made. For instance, if the port managers attempt to reduce the sea transport cost by increasing the annual allocated number of ship voyages classed 150,000-ton for economies of scale, they have no choice but to suffer a significant increase in queueing cost due to port congestion. To put it differently, there are trade-off relationships among the costs incurred in port, yard, and at sea. We utilized a computer simulation result to perform a couple of regression analyses in order to figure out the appropriate range of allocated number of voyages of each ship class using a heuristic approach. The detailed analytical results will be shown at the main paper. We also suggested a net present value(NPV) model to make a proper investment decision for an additional berth of 200,000-ton class that alleviates port congestion and reduces transport cost incurred both in port and at sea.

• Information Systems Review
• /
• v.18 no.4
• /
• pp.141-154
• /
• 2016

Mobile application is growing explosively with the advent of a new technology: smartphones. Mobile application is a new marketing channel and performs as a start-up platform. This study examines the effect of mobile application on the off-line market. Despite the continuous declining demand for taxi service, paradoxically, the supply of taxi service has increased. The taxi industry can be categorized into general taxi and call taxi. General taxi is accidental and inefficient because it has to search for its own passenger. As call taxi takes the request of a passenger, it is more efficient than general taxi. However, the current defective passenger-taxi driver matching system and insufficient taxi driver management hinder the development of the call taxi market. Differences in differences (DID) is an econometrical methodology that examines whether or not an event has meaningful influence. This research uses DID to investigate the effect of the Kakao taxi application on the call taxi industry. Furthermore, it examines the effect of major companies' reckless diversification, which is considered unethical behavior. The passengers of call taxi data from August 2014 to July 2015 and those of designated driving service data of the same period were collected as the control group.

• Journal of Digital Contents Society
• /
• v.15 no.2
• /
• pp.289-300
• /
• 2014

Cloud computing helps users to save a significant amount of cost that is related to infrastructure investment, management, and maintenance. In this paper, we study the conversion planning from campus legacy web servers into an integrated cloud computing web server system. We also analyze the conversion profit when campus web servers are integrated into a cloud computer. We first investigate the cost of legacy system model of campus web servers operated by individual laboratories, departments, institutes and so on. Next, we set up a cloud computer model for the integrated web services meeting the same performance requirements. Then, we derive the conversion profit. From the result of the derivation, we see that the conversion can be effectively applied to and adopted by mid or large sized campuses and similar institutions that provide web services.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.2
• /
• pp.573-582
• /
• 2014

Since there is no clear installation criteria on minimum spacing between signalized intersection and minor road, many problems have occurred in terms of traffic operation and safety. Even though many studies about entrance/exit intersection have been done in operational aspects, there is no specific and detailed research between the signalized intersection and minor road by now. Thus, this research suggests the optimal spacing between signalized intersection and minor road considering traffic operation and safety. Also, survey on vehicle behavior was conducted in this research. In conclusion, by suggesting the required minimum spacing between signalized intersection and minor road, it can be contribute in establishing and operating the installation criteria between signalized intersection and minor road.

• KDI Journal of Economic Policy
• /
• v.9 no.1
• /
• pp.43-67
• /
• 1987

산업구조(産業構造)의 고도화과정(高度化過程)에서는 고용흡수력(雇傭吸收力)이 감소(減少)하는 양적측면(量的側面)의 과제(課題)와 기술인력(技術人力)의 수요(需要)가 상대적으로 증가(增加)하는 질적측면(質的側面)의 인력정책과제(人力政策課題)가 동시에 야기(惹起)된다. 본(本) 논문(論文)에서는 이러한 여건변화(與件變化)에 대응(對應)하는 정책과제(政策課題)를 도출(導出)하기 위하여 인력수요(人力需要)의 결정요인(決定要因)을 실증분석(實證分析)하였다. 거시분석(巨視分析)에서는 1970~84년(年) 기간(期間)의 연간(年間) 시계열자료(時系列資料)를 이용(利用)하여 노동수요함수(勞動需要函數)를 추정(推定)하여 산업별(産業別) 결정요인(決定要因)을 비교분석(比較分析)하였으며, 미시분석(微視分析)에서는 섬유(纖維) 자동차(自動車) 전자산업(電子産業)에서 임의추출(任意抽出)한 200개(個) 표본기업(標本企業)에 대한 횡단면자료(橫斷面資料)를 이용(利用)하여 기업(企業)의 인력수요행태(人力需要行態)를 분석(分析)하였다. 산업별(産業別) 노동수요(勞動需要) 분석결과(分析結果)를 보면, 자본비용(資本費用)에 대한 노동비용(勞動費用)의 상대적상승(相對的上昇)이 노동수요(勞動需要)를 감소(減少)시켜 왔으나, 고용(雇傭)은 기본적으로 자본투자(資本投資)로부터 더 큰 영향을 받는 것으로 나타났으며, 또한 자본(資本)의 고용창출효과가(雇傭創出效果), 특히 제조업부문(製造業部門)에서, 시간(時間)의 경과(經過)에 따라 감소(減少)하는 것으로 분석(分析)되었다. 미시분석결과(微視分析結果)를 보면, 전문대졸(專門大卒) 및 고졸학력(高卒學力) 근로자(勤勞者)에 대한 수요(需要)는 중소기업(中小企業)에서, 대졸(大卒) 및 중졸이하학력(中卒以下學歷) 근로자(勤勞者)는 대기업(大企業)에서 흡수(吸收)하려는 것으로 나타났으며, 생산요소중(生産要素中) 노동(勞動)에 대한 투자우선순위(投資優先順位)는 자동차산업(自動車産業)에서 높게 나타났으며, 숙련기능인격(熟練技能人格)에 대한 수요(需要)는 세 산업(産業) 모두 높게 나타났다.