• Fire Science and Engineering
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• v.30 no.2
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• pp.68-74
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• 2016

In semi-transverse ventilation system applied for road tunnel, adjustment of the port opening ratio is an essential part for uniform airflow rate per unit length over the entire tunnel. However, it has not been considered decently throughout the design process and operating of the tunnel. Therefore, in this study, we developed a program for the calculation of the opening size ratio of supply or exhaust port in transverse ventilation system and carried out the research to present a management plan for the port. In supply duct system, the opening size of the port had a tendency to increase and then decrease later when it gradually becomes closer toward the bulkhead at the beginning of the duct the minimum opening degree is to appeared as 56%. In the exhaust system, port size is the smallest at the beginning of duct as 15%, has shown a tendency to increase towards the bulk head. As results of estimating the air flow rate for 300 m intervals, the exhaust flow rate in the center of tunnel appeared to be extremely low as 8.1% and 12.5% when port size is constant and is adjusted supply type. Thus, even if the normal ventilation efficiency is declines, yet it is highly recommend adjusting the port size in order to obtain a uniform flow rate at fire accidents.

• Journal of Korea Port Economic Association
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• v.35 no.1
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• pp.1-18
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• 2019

It is debated whether the time value of bulk cargo should be reflected in the economic assessment of SOC investments. The purpose of this study is to present the basic considerations that should be addressed to reflect the time value of bulk cargo. The study first tried to understand the status of foreign countries, related research cases, and the limitations of applying findings to the domestic situation. Further, the method of reflecting the time value of bulk cargo, as well as the extent to which it is reflected, varies across countries. Furthermore, the reflection of the time value derived from the transport selection model remains a controversial issue. To overcome these limitations, this study suggests basic environment considerations to reflect time. Although the need to reflect the time value of bulk cargo is fully recognized, it seems that there are issues that need to be reviewed and solved before its actual implementation. To complement this, further research needs to be conducted, and it is expected that more clear guidelines will emerge.

• Journal of Navigation and Port Research
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• v.40 no.4
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• pp.223-230
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• 2016

While marine transport freight is steadily increasing, people are more interested in terminals handling cargo. But the domestic researches on terminals were almost on container terminal. This study attempted to study the service quality for bulk terminals. The users of bulk terminal services were divided into shipowners and shippers to compare their differences by using bulk terminal service provided. During the attributions proposed in this study, Tangibles were descripted by the numbers of berth or depth, facilities, and so on. So it was suitable to consider the tangibles by formative indicators. And also this study has tried using "reflective model" and "formative model" to make a measurement model for comprehensive analyses. The results showed that all of the items were significant except the relation between empathy and performance satisfaction in the overall measurement model analyses. User groups difference analyses results have showed that the trust responsiveness impact on performance satisfaction was more importantly assessed by shippers than by shipowners. It was expected to use the results of this study as a good strategic resource to help bulk terminal administrators make various expansion plans to improve the bulk terminal's competitiveness in the future.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.67-72
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• 2004

Many port states such as New Zealand, the USA, Australia and Canada have strict regulations to prevent ships which arrive in their port from discharging polluted ballast water which contain harmful aquatic organism and pathogens. They are notified that transfer of polluted ballast water can cause serious injury to public health and damage to property and environment. For this reason, they perceived that the ballast exchange in deep sea is the most effective method, together with submitting the ballast management plan which contains the effective exchange method, ballast system and safety consideration. In this study, we pursued both nautical engineering analysis and optimization of algorithm in order to generate the sequence of stability and rapidity. Heuristic Algorithm was chosen on the basis of optimality and applicability to a sequential exchange problem. We have built an optimized algorithm, for automatic exchange of ballast water, by redefining core elements of the $A^\ast$ algorithm, such as node, operator and evaluation function. Final version of the optimized algorithm has been applied to existing bulk carrier and the performance of the algorithm has been verified successfully.

• Journal of Korea Port Economic Association
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• v.29 no.2
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• pp.63-79
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• 2013

The fundamental endeavor of this study is to investigate the asymmetric relationship between bunker price and Baltic Dry-bulk Index (hereafter BDI). Previous investigations employ linear form based analysis between oil price and BDI but we develop nonlinear and asymmetric cointegration method, which is properly able to capture the decreasing and increasing periods differently. The empirical results show there is no relationships in linear model (e.g. Engle and Granger's methods). On the contrary, our estimate reveals there is significant long-run relationship with asymmetric framework, which implies the necessity of nonlinear and asymmetric consideration to the bunker price analysis.

• Journal of Korea Port Economic Association
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• v.35 no.3
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• pp.93-108
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• 2019

This study aims to suggest a containerization plan for non-standardized cargo; it also reveals the significance of containerization in facilitating freight inducement and cargo creation for increasing the competitiveness of the Gwangyang port container terminal and checking excessive competition among terminal operators. Therefore, this study suggested a containerization plan and its significance by dividing 14 items, ones with low containerization ratios or undergoing containerization, bulk, and liquid cargoes. In the case of general cargo, it will be necessary to raise the utilization rate by remodeling a general container or improving cargo loading techniques. In the case of bulk cargo, it will be necessary to exploit the benefits of containerization in preventing product deterioration due to rain, facilitating the sale of small orders, ensuring clean cargo handling, and reducing logistics cost, among others. In the case of liquid cargo, it will be necessary to order and sell liquid cargo in small quantities by using superior quality, safe, and durable Flexitank or Flexibag products, which offer transportation convenience and reduce time and costs.

• Journal of Korean Society of Forest Science
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• v.97 no.4
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• pp.385-391
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• 2008

Republic of Korea (ROK) log import companies have clustered around In-cheon, Jeon-buk and Busan. This reason related to port for log import. This study analyzed the quantity of Whole imported log transported by port. As the result of analysis, In-cheon port accounted for 56.9% log import, which is the maximum log import port in ROK. Next Bu-san port 20.9%, Gun-san port 17.9%. However, these port have declined the quantity of imported log transported since 2000. Gun-san port and Dong-hae port increased narrow range. The reason of why In-cheon and Bu-san port declined log import and Gun-san and Dong-hae port increased is that a sudden rise in the price of log in 2003, and import of using a container ship increased. In the addition, log import from Far eastern Russia, Germany and America increased through a container ship, however, declined log import through a bulk ship. Most of imported log at In-cheon port are from New zealand and Russia, imported logs at Bu-san port are almost from US and New zealand.

• Journal of Mechanical Science and Technology
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• v.16 no.11
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• pp.1457-1469
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• 2002

This paper is the first of several companion papers, which investigate axial stratification process and its effects in an Sl engine. The axial stratification is very sophisticate phenomenon, which results from combination of fuel injection, port and in-cylinder flow and mixing. Because of the inherent unsteady condition in the reciprocating engine, it Is impossible to understand the mechanism through the analytical method. In this paper, the ports were characterized by swir and tumble number in steady flow bench test. After this, lean misfire limit of the engines, which had different port characteristic, were investigated as a function of swirl ratio and injection timing for confirming the existence of stratification. In addition, gas fuel was used for verifying whether this phenomenon depends on bulk air motion of cylinder or on evaporation of fuel. High-speed gas sampling and analysis was also performed to estimate stratification charging effect. The results show that the AFR at the spark plug and LML are very closely related and the AFR is the results of bulk air motion.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.202-209
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• 1998

For development of SDI(Spark-ignited Direct Injection) engine, stratified mixture formation with adequate strength at spark plug was required in wide range of engine operating conditions. So, spray structure under high ambient pressure and spray distribution after impingement on piston bowl in motoring engine was visualized by using laser equipments. Also, incylinder bulk flow structure was measured by using PIV (Paiticle Image Velocimetry) system. Counter-rotating tumble port and bowl piston was found effective to conserve bulk motion directed to spark plug in compression stroke. In addition, mask attached near valve seat in intake port was proposed to attenuate conventional tumble component and enhance counter-rotating tumble component.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.54-58
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• 2002

This paper describes the theoretical analysis and performance of a 2.4㎓ bulk-driven downconversion mixer, where the LO signal is input via the bulk. A mixer core designed with a 0.18$\mu\textrm{m}$ CMOS process is able to operate under 0.8V∼1V supply voltage. The RF, LO, and IF port frequencies are 2.45㎓, 2.4㎓, and 50MHz, respectively. The measurement results exhibit conversion gain of -1.8㏈, l㏈ compression point of -17㏈m and IIP3 of -4㏈m with 0㏈m LO power. The power consumption is as small as 4mW.