• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.222-224
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• 2016

본 연구에서는 우리나라 도선 서비스 현황과 운영제도 및 구조적인 문제점을 살펴보고 현행 도선 서비스가 가지고 있는 문제점을 계층적으로 분석하여 최우선적으로 개선해야 할 우선 순위를 도출하고자 한다. 우리나라의 도선 서비스 개선에 관한 주요 요인들 중에서, 첫번째로 도선사의 서비스 마인드가 가장 중요한 항목으로 나왔으며, 세부평가 속성들 중에서도 도선 서비스의 재평가가 최고우선 평가항목으로 도출되었다.

• Journal of Navigation and Port Research
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• v.44 no.6
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• pp.564-570
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• 2020

In order to propose a realistic demand forecast for harbor pilots, define a direction for securing a supply of pilots for the betterment of national logistic services, and ensure the competitiveness of Korean ports, this study intended first to propose a new forecasting process for harbor pilot requirements through conducting analysis of determining factors affecting harbor pilot demand. Additionally, analyzing relevant previous studies allowed us to estimate the number of pilots required in the past and asses the studies limitations. Our second purpose was to propose a more stable allocation method among different pilot areas after forecasting the demand of harbor pilots until 2027 through application of the new forecasting process. From this application, the total number of pilots required was forecasted at 270, suggesting the total demand for harbor pilots will be increased by 7.57% compared with 251 pilots in 2018.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.819-826
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• 2019

To accurately forecast the supply and demand of harbor pilots, it is necessary to derive the determinants of demand because they are directly linked to securing the safety of ships and ports. The securing of an appropriate numbers of harbor pilots can create conflicts of interest among the pilots, the Ministry of Oceans and Fisheries, and users of pilotage services as it is also a matter directly related to harbor pilots' income. Therefore, a measure is needed to ensure a suitable number of pilots can be maintained, through which high quality pilotage services can be provided. This can be achieved by deriving reasonable determinants for estimating and forecasting demand, which satisfy all stakeholders involved in pilotage service. To reveal the challenges posed by the current determinants regarding the demand for harbor pilots used by the Central Pilotage Operation Council, and arrive at solutions, this study derived three determining factors, namely the total annual average piloting time, the average working hours of pilots, and the current number of pilots. These were used to determine the demand for harbor pilots. This study used a survey and analysis of current determining factors, a questionnaire survey administered to the interested parties, a case study of selected countries, and so on, as the research methodology.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1139-1140
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• 2008

This paper is designated to introduce the method of reducing stand-by Power of SMPS applied PLC(Power Line Communication) and its implementation. PLC modem consists mainly of PLC Module, Coupling Circuit, ZCP(Zero-Cross Point) Circuit and Power Supply Circuit. By controlling power from Power Supply Circuit to PLC Module and ZCP Circuit, the reduction of Stand-by Power is established. When this method is applied to SMPS used for a low-speed PLC, about 50% power reduction is provided, compared to the other case to which it is not applied.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1947-1948
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• 2008

This paper presents the implementation of Power Line Communication(PLC) module which can reduce standby-power consumption. The suggested PLC module consists of PLC modem, coupling circuit, ZCP(Zero-Cross Point) Circuit and main SMPS control relay. The test results under power line communication test-bed used home appliance show the 77% saving of standby-power.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.856-866
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• 2021

The increasing international awareness regarding air pollutant reduction has resulted in increasing demand for eco-friendly ships; hence, electric ships are being actively developed by various countries. Presently, studies on electric ships are mainly focused on electric propulsion systems and electric motors. However, from the ship perspective, there are no studies on conceptual designs for coastal car ferries powered by removable power supply systems. In the present study, the main research consideration is regarding the conceptual design of a fully electrified car ferry using a battery-based removable system as the main power source. By analyzing the dimensions of more than 100 domestic coastal car ferries, the main criteria satisfying the requirements for developing a suitable vessel were derived, and a study on intact/damage stability was conducted considering the application of a removable battery truck. Further analyses of the problems concerning the conceptual design were also performed to derive solutions.

• Journal of Korea Port Economic Association
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• v.32 no.4
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• pp.149-163
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• 2016

Seafarers are an essential resource in maritime industries, which provide navigation skills, vessel maneuvering skills and fishing skills in the fishery industry. They also work as a driving force in pilotage, port operation, vessel traffic service, and marine safety. Other areas in maritime services, which rely on seafarer include safety management of ships, supervisory activities, and maritime accident assessment. In these ways, Korean seafarers have contributed to the growth of Korean economy. However, there have been issues of high separation rate, shortage of supply, multi-nationality, multiplicity of culture caused by employment of foreign seafarers, and aging. The present paper finds that maritime officers and fishery officers demonstrate differences in the statistics of on-board job taking and separation: the separation rate of fishery officers is higher than that of maritime officers. The existing data and statistics by the Korea Seafarer's Welfare & Employment Center could be improved by changing its structure from time series to panel data. The Korea Seafarer's Welfare & Employment Center is the ideal institution for collecting the panel data, as it has already accumulated and published relevant statistics regarding seafarer. The basic design method of the panel data is to adopt and improve it by including the information on ratings of maritime and fishery industries, ranks in a ship, personal information, family life, and career goal. Panel data are useful in short- and long-term forecasts of supply of Korean seafarers; demand evaluation of education, training, and reeducation of the seafarers; demographical dynamic analysis on Korean seafarers; inducement policy of long-term on board job taking in harmony with man-power demands in marine industries such as pilotage service; implementation of job attractiveness policy on Korean seafarers; and employment stabilization of Korean seafarers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.7
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• pp.566-569
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• 2018

A power line coupler that can apply high-frequency power to a railway overhead line structure was analyzed. It is difficult to supply auxiliary power to an overhead line in a high-voltage environment, and doing so requires a long-distance transfer. A method is proposed that utilizes the resonance on the Rogowski coil, which does not use a magnetic core. A simple overhead line structure was fabricated that consisted of a contact wire, messenger wire, and dropper. Couplers of various sizes were fabricated and deployed on the messenger wire, and the transfer characteristics of the two couplers were compared at a distance. As a result of applying the matching circuit to the coupler, the transmission efficiency was 53% at a distance of 2.5 m. The proposed method shows that it is possible to apply the auxiliary power by using the existing conductor in a special structure, such as the overhead line.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.3
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• pp.115-125
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• 2001

To examine the movement of the freshwater discharged artificially into the estuary during ebbing period in the Keum River dike we observed surface salinity variations in three stations along the estuary channel in May 1998 and July 1997 and surface temperature and salinity along the ferry-route between Kunsan and Changhang during eighteen days in July 1999. Based upon the typical features of observed salinity variation, we analyzed the excursion and decay processes of the discharged water. When freshwater is discharged, the low-salinity water forms strong salinity front over the entire estuary width, which basically moves forth and back by tidal modulation along the channel, producing the sudden change of surface salinity with the front passage. Salinity distribution along the channel, which is deduced from time variation of mean salinity over the estuary width, after one tidal period from gate operation suggests that diluted low-salinity water is trapped to the front and surface salinity increases gradually toward the upstream region. This frontal distribution of salinity is interpreted to be produced by the sudden gate operation supplying and stopping of freshwater within about two hours. Daily repeat of freshwater discharge produces separation (double front) or merge between decaying and new-generated fronts depending on dike-gate opening time, and the front decays with salinity increasing if the freshwater supply is stopped more than two days. In addition, the observed fluctuations and deviations in surface salinity variation is explained in terms of the differences of fronts intensity, their transition time and temporal salinity front running along the channel, which can be generated due to artificial gate-operation for the discharging time and water volume in the estuary dike.

• Journal of dental hygiene science
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• v.8 no.2
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• pp.89-96
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• 2008

Effects of sodium fluoride exposure on the amelogenesis during fetal formation were investigated using 11 days rat incisor of control group and two experimental groups. According to results of morphological analysis using an electron microscope, enamel organ in the rat incisor consisted of presecretory, secretory, and maturation zone, especially maturation zone had ruffle-ended ameloblasts (rAB) that additionally supply inorganic ions and smooth-ended ameloblasts (sAB) that remove water and organic compounds. Such a histological composition was same in fetal and adult rats. According to experimental results using calcein (green fluorescence) in order to reveal the modulation cycle of ameloblast, modulation cycle of experimental group decreased on an average one time than control group, as increase of density of sodium fluoride indicated that thickness of smooth-ended ameloblast decreased. Also ratio of thickness on sagittal total length of sAB increased than rAB in experimental groups than control group. In total length of teeth, an injected 100 ppm sodium fluoride group was similar control group but as injected 200 ppm group became short. In experimental group, thickness of sAB and rAB became narrow to the tip of cutting edge. According to concentration of sodium fluoride grows, the modulation cycle and total length of teeth were decreased, finally it prevented teeth growth.