• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.380-388
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• 2005

This paper presents analysis results of the effects of RF filter characteristics on the system performance of impulse radio. The impulse radio system transmits modulated pulses having very short time duration and information can be extracted in receiver side based on cross-correlation between received and transmitted pulses. Accordingly, the pulse distortion due to in-band group delay variation can cause serious system performance degradation. In general, RF bandpass filters inevitably cause group delay difference to the signal passing through the filter which is proportional to its skirt characteristic due to its resonance phenomenon. For time as well as frequency domain analysis, small signal scattering parameter $S_{21}$ and its Fourier transform are used to characterize output pulse waveform under the condition that the input and output ports are matched. The output pulse waveform of the filter is predicted based on convolution integral between input pulse and filter transfer function, and resulting BER performances in the BPM and PPM based impulse radio system are calculated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.678-685
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• 2013

In this paper, we propose a design of dual-band patch antennas for Global Positioning System(GPS) applications, and the designed antenna is used as an individual element of GPS arrays. A low distortion and a high isolation of the array are achieved by adjusting rotating angles of each array element. The antenna consists of two radiating patches that operate in the GPS $L_1$ and $L_2$ bands, and the two ports feeding network with a hybrid chip coupler is adopted to achieve a broad circular polarization(CP) bandwidth. The rotating angles of each antenna element are varied with four directions(${\phi}=0^{\circ}$, ${\phi}=90^{\circ}$, ${\phi}=180^{\circ}$, ${\phi}=270^{\circ}$) in order to minimize the pattern distortion and maximize the isolation among array elements. The measurement shows bore-sight gains of 0.3 dBic($L_1$) and -1.0 dBic($L_2$) for the center element. Bore-sight gains of 1.6 dBic($L_1$) and 1.0 dBic($L_2$) are observed for the edge element. This results demonstrate that the proposed antenna is suitable for GPS array applications.

• 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.

• Journal of Navigation and Port Research
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• v.26 no.2
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• pp.167-175
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• 2002

Busan Port which is the representative social overhead capital facilities for international trade of goods has need the driving force for economic development in Korea. Therefore, the central government should play the major role in building a rear road to Busan Port in order that it may function as a moor port of Northeastern Asia through the systemization of mutual assistance among connected facilities, completely equipped with port-related facilities befitting to the principal port of imports and exports. In this study, the validity of container tax is being examined, analyzing container tax which is considered as an obstacle to the development of Busan Port and its purpose, and grasping the present conditions by the realistic speculation on container tax issues and its abolition. First, the port rear road as a social overhead capital facilities, which connects port and expressway, should be considered as part of port, and port is social overhead capital invested by government. Second, the Busan City imposes taxes on container. As a result, a shipper and a shipping company are paying a double charge by paying container tax with port dues. Third, Empty container and Tranship container are the factor of Busan city traffic jam but their was excluded from container tax. This is deviate from equilibrium of the tax object. Forth, it has bad influence upon the competitiveness of Busan Port as Northeastern logistics base, as other ports who are competing with Busan Port like china, Taiwan, Japan's port make their competitiveness strong by decreasing the cost of port dues.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.439-445
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• 2005

Recently, owing to the increasing demand on the simplification of arrival and departure procedures, IMO's (International Maritime Organization) Facilitation Committee (FAL) is carrying out the standardization project of arrival and departure formalities and clearance form. Also, many port authorities of developed countries are making active researches for the smooth flow and efficiency of the information inbound and outbound ships by way of simplifying their formalities or through electronic means. However, this standardization project cannot be done by one country but by mutual cooperation among related nations. And to carry out this task, the first thing to be done is to standardize the formalities and document form, and to integrate information. To this end, this study has reviewed the model cases of advanced ports of developed countries with regard to their simplification and standardization efforts. And also we have analyzed the formalities and clearance form of the three countries Korea, China, and Japan. And then for the solution of common problems of three countries, this paper has suggested an ebXML-based Global Port B2B framework. Through this framework, we can reuse and automate the necessary information on the arrival and departure of ships, consequently realizing simplification, and laying a foundation for the introduction of e-commerce to the port industry.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.319-327
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• 2015

This study can be summarized as follows : First, main participant, procedure and method of redevelopment of Inner port shall be additionally reviewed. Demands of stakeholder of Incheon Inner Port are actively accommodated to avoid the disruption in undertaking the project. Second, it must ensure the adequacy and appropriateness of policies regarding the redevelopment of the Inner Port in Incheon. It is necessary to obtain consent of people on this project. Third, appropriate system must be established to undertake the project. For this purpose, the governance system shall be built to collect the opinions of the people. The conclusions of this study are as follows. The national master plan and modify plans of Port redevelopment have been being undertaken based on Port Act. Incheon Inner Port redevelopment has been showing slight discrepancy with that of other ports. It's the essential part to coordinate the opinions and needs between the parties prior to the establishment of a redevelopment plan. This can be settled when it's warranted for dock workers to secure the job, and for port companies to provide replaceable piers as the precondition. In addition, eco-friendly waterfront leisure space shall be planned and alternative policies shall be arranged with accommodating the needs of local residents and merchants.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.379-385
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• 2017

In general, distribution board, panel board and motor control center can be installed over a wide area such as residence of group, building, schools, factories, ports, airports, water service and sewerage, substation and heavy industries that are used to supply converts the voltages extra high voltage into optimal voltage. There are electrical accidents due to rise of contact temperature, loose contact between busbar, deterioration of the contact resistance, over temperature of the busbars. In this paper, we designed and implemented the busbar joint and temperature measurement system, which can measure the joint resistance of busbar and loose connection between busbar using potentiometer and non-contact infrared sensor. The experimental results show that tightening the bolt and nut is fully engaged, resistance was decreased and maximum error range was 0.1mm. Also, the experimental result showed that the temperature at the contact area is increased from $27.3^{\circ}C$ to $69.3^{\circ}C$by the contact resistance.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.134-142
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• 2003

We present an ATM switch architectures based on the multistage interconnection network(MIN) for the efficient multicast traffic control. Many of these applications require multicast connections as well as point-to-point connections. Muiticast connection in which the same message is delivered from a source to arbitrary number of destinations is fundamental in the areas such as teleconferencing, VOD(video on demand), distributed data processing, etc. In designing the multicast ATM switches to support those services, we should consider the fairness(impartiality) and priority control, in addition to the overflow problem, cell processing with large number of copies, and the blocking problem. In particular, the fairness problem which is to distribute the incoming cells to input ports smoothly is occurred when a cell with the large copy number enters upper input port. In this case, the upper input port sends before the lower input port because of the calculating method of running sum, and therefore cell arrived into lower input port Is delayed to next cycle to be sent and transmission delay time becomes longer. In this paper, we propose the cell splitting and group splitting algorithm, and also the fairness scheme on the basis of the nonblocking characteristics for issuing appropriate copy number depending on the number of Input cell in demand. We evaluate the performance of the proposed schemes in terms of the throughput, cell loss rate and cell delay.

• Journal of the Institute of Convergence Signal Processing
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• v.17 no.2
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• pp.53-60
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• 2016

In this paper, we introduce the implementation and test results of a new method of correlated result storage to achieve the full performance of the Daejeon hardware correlator. Recently, the observation of 8 Gbps speed, which is the maximum observational standard of KVN(Korean VLBI Network), has been performed. The correlation processing using the Daejeon hardware correlator is also required. Therefore, a new correlation result storage introduction has become necessary. The maximum correlation result output speed of the Daejeon hardware correlator is 1.4 GB/sec per 25.6 ms integration time. The conventional correlation result storage system can not cope with the maximum correlation output speed of the Daejeon hardware correlator, and the output speed is limited to 1/4. That is, among the four input ports of the Daejeon hardware correlator, the three inputs are limited to correspond to the observation rate of 1 Gbps. This new storage system uses the Gluster file system among many of the latest technologies used in storage systems. In tests that meet the maximum output rate of 1.4 GB/sec for the Daejeon hardware correlator, 350 MB/sec for each of the four optical outputs, resulting in 1.4 GB/sec in total.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.2
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• pp.77-82
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• 2017

Recently, the possibility of abnormal waves of which height is greater than design wave height have been increased due to the climate change, and therefore it has been urgent to secure the stability for harbor structures. As a countermeasure for improving the stability of conventional caisson breakwaters, a method has been proposed in which adjacent caissons are interlocked with each other to consecutively resist the abnormal wave forces. In order to reflect this research trend, the reduction effect of the maximum wave force resulted from introducing a long caisson has been presented in the revision to the design criteria for ports and fishing harbors and commentary. However, no method has been proposed to evaluate the stability of interlocking caisson breakwater. In this study, we consider the effect of the phase difference of the oblique incidence of the wave based on the linear wave theory and apply the Goda pressure formula for considering design wave pressure distribution in the vertical direction. Sliding stability assessment formula of an interlocking caisson breakwater is proposed for regular, irregular, and multi-directional irregular wave conditions.