• Journal of Navigation and Port Research
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• v.40 no.5
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• pp.291-297
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• 2016

Ulsan Port is the main port for handling liquid cargo because of natural environmental conditions and the distribution of port infrastructures in Korea. Damage to both liquid cargo vessels and the port structure caused by maritime accidents could have a serious impact on property and human lives as well as the marine environment. For safe navigation, the parties concerned should ensure the suitability of various design criteria at the harbor design stage. In this paper we analyze and compare various domestic and international harbor design criteria, and then apply each criteria to Ulsan port to evaluate its overall safety. Additionally, this paper specifies certain precautions in terms of reviewing a ship's safety for each channel at Ulsan Port, and suggests possible improvements to optimize channel design.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.943-949
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• 2009

In this paper, the 5.9GHz WAVE(Wireless Access in Vehicular Environments) channel modeling is used by the Jakes channel model for the suitability of the fast wireless channel fluctuation. The performance analysed the fading signal constellation and the spectrum in the IEEE 802.11p spectrum mask, the Doppler effect, the modulation scheme. In addition, the vehicular speed, exactly the performance analysis the WAVE communication systems follow the Doppler effect.

• Journal of Navigation and Port Research
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• v.32 no.2
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• pp.141-148
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• 2008

This paper is structured into three main parts and a conclusion. The main section provide definitions of efficiency, effectiveness and performance in terms of the distribution channel, followed by a review of related performance measurement, before discussing difficulties of measurement. According to the theoretical approach, it appears that key theroretical issues are centered around customer service, logistics excellence, time compression, the use of IT, and a move towards integrated logistics. The empirical approach shows that in the past, various financial performance indicators were regarded as relevant management information. However, today, management needs additional performance indicators. Therefore, external assessments of effectiveness must be performed to measure customers' satisfaction with the physical flow of product through the distribution channel network. So, what is needed is to take previous normative and explorative research and progress through a framework by developing valid measures of distribution channel's effectiveness and efficiency, and identifying research methodologies suited to the data collection requirements.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.2
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• pp.43-51
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• 2017

In this study, the effect of the steering vector model mismatch due to array uncertainties on the performance of array processing was analyzed through simulation, along with the alleviation of the model mismatch effect depending on array calibration. To increase the reliability of the simulation results, the actual steering vector of the array antenna obtained by electromagnetic simulation was used along with the Jahn's channel model, which is an experimental channel model. Based on the analysis of the power spectrum for each direction, beam pattern, and the signal-to-interference-plus-noise ratio of the beamformer output, the performance deterioration of array processing due to array uncertainties was examined, and the performance improvement of array processing through array calibration was also examined.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.1
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• pp.102-109
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• 2016

The hydrodynamic interaction between two large vessels can't be neglected when two large vessels are closed to each other in restricted waterways such as in a harbor or narrow channel. This paper is mainly concerned with the ship maneuvering motion based on the hydrodynamic interaction effects between two large vessels moving each other in curved narrow channel. In this research, the characteristic features of the hydrodynamic interaction forces between two large vessels are described and illustrated, and the effects of velocity ratio and the spacing between two vessels are summarized and discussed. Also, the Inchon outer harbor area through the PALMI island channel in Korea was selected, and the ship maneuvering simulation was carried out to propose an appropriate safe speed and distance between two ships, which is required to avoid sea accident in confined waters. From the inspection of this investigation, it indicates the following result. Under the condition of $SP_{12}{\leq}0:5L$, it may encounter a dangerous tendency of grounding or collision due to the combined effect of the interaction between ships and external forces. Also considering the interaction and wind effect as a parameter, an overtaken and overtaking vessel in narrow channel can navigate while keeping its own original course under the following conditions; the lateral separation between two ships is about kept at 0.6 times of ship length and 15 degrees of range in maximum rudder angle. On the other hand, two ships while overtaking in curved narrow channel such as Inchon outer harbor in Korea should be navigated under the following conditions; $SP_{12}$ is about kept at 1.0 times of ship length and the wind velocity should not be stronger than 10 m/s.

• Journal of the Korean Institute of Navigation
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• v.18 no.2
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• pp.41-56
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• 1994

This paper was a part of the risk management in planning a channel. It utilized Korea Marine Training & Research Institutes(KMTRI) which Houses a real-time, full-mission shiphandling simulator to examine the safety of the ship's transit in the planned channel of Asan port. 6 competent Captains participated in this study. The vessel modelled was a 60,000-ton ship. The two variables(factors) examined were environ-mental conditions such as flood-and-ebb current condition and day-and-night condition. The two variables were combined to produce four experimental conditions. To evaluate the safety of the environmental conditions, two categories of performance measures were analyzed. They were vessel's proximity to channel boundary and vessel controalbility. The findings regar-ding the effects of environmental conditions were as follows : - Closest Point of Approach(CPA) to channel boundary was enough for 60,000-ton ship to transit th-rough the channel with 99.999% confidence level. - Closest Point of Approach(CPA) to channel boundary further was under against-current condition than under with-current condition. -Vessel controlability was better under against-current condition than under with-current condition. -Vessel controlability was better under inbound transit than under outbound transit.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.04a
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• pp.101-110
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• 1998

The safe passing maneuver of a large vessel along the designed course through a narrow channel in the flow of strong current is greatly related with her maneuvering characteristics. This paper treats maneuvering characteristic of a large vessel changing her course with the use of her control surface in a narrow channel with strong current. In this paper, the author proposed mathematical models of calculating maneuvering motions of the very large LNG tanker altering course using her control surface and calculated passing tracks of the vessel through the channel and compared the calculated results with those of maneuvering simulations by a desk-top simulator. In general the motions with the calculated values and the simulated motions are well coincided with each other.

• Journal of the Korean Institute of Navigation
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• v.21 no.4
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• pp.39-47
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• 1997

We researched the mechanism on th flucturain of Bottom Cold Water in the western channel of Korea Strait, using 13 years(1981~1933) oceanographic data of FRDA. The bottom cold water in the western channel appears more often in summer and fall than in winter and spring, and its year-to-year variation of temperature is very large. Such variation seems to be closely related with the variations of cold waters in the subsurface layer of the southwestern East Sea. According to the longitudinal temperature distribution along the korean southeastern coast, a density difference occurs all the time at the still deepth between the western channel and the southwestern East Sea. Thus, it is inferred that the cold waters would intrude into the western channle form the subsurface layer in the southwestern East Sea as a density-driven current, and it intensity depends upon the density difference.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.214-216
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• 2022

본 논문에서는 시정계에 비해서 낮은 가격으로 개발이 가능한 카메라 시스템과 촬영한 사진으로 해무 강도를 측정하는 방안을 제안한다. 항로표지에 부착이 가능하고 360도 촬영이 가능한 카메라 시스템 구현 내용을 설명하고 해무의 강도를 측정하기 위해 안개 모델과 Dark Channel Prior(DCP)를 이용해 해무 강도를 측정하는 알고리즘을 개발하였다.

• Journal of Advanced Navigation Technology
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• v.6 no.3
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• pp.203-210
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• 2002

In this paper, the BER performance of IEEE 802.11a OFDM WLAN system is obtained by simulation and it is shown that the proposed modified channel estimation algorithm improves the channel estimation performance of the system. The wireless channel used in channel simulation includes AWGN and delay spread channel implemented by TDL model. At first, the performance of OFDM WLAN system according to data rate and coding rate defined in standard is evaluated in AWGN channel. Then, imperfect channel estimation in indoor wireless channel is considered. After the performance of conventional channel estimation scheme using only two long training symbols is evaluated, and that of proposed modified channel estimation scheme using additional 8 short training symbol is compared with it. From the simulation results, it is shown that modified channel estimation scheme provides reduced channel estimation error and improves the channel estimation performance due to noise averaging effect with the same preamble format as defined in specification.