• Journal of the Korean Geographical Society
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• v.24
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• pp.1-18
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• 1981

본 연구는 미국에서 boat공업의 중심지 중의 하나인 Seattle의 boat 공업의 입지와 그 변화를 고찰하므로서 소기업의 입지를 구명하려고 하였다. 본 연구에서는 먼저 Seattle에서 소규모 boat제조업체가 가장 많이 집중한 Washington호와 Shilshole 만간의 운하지역을 연구지역으로 선정하려 이 지역내에 입지하고 있는 boat 제조업체의 기업주와 interview한 결과를 기본자료로 이용하였다. 이상에서 얻어진 결과는 다음과 같았다. 연구지역의 소규모 boat 공업은 boat제조에 흥미와 능력을 가진 기업가들이 boat 공업에 유리한 Seattle의 환경의 영향을 받아 그들의 기업을 그들의 오랜 거주 지역에서 시작하므로서 발생하게 되었다. 그러나 담수를 지향하는 이 공업의 입지상의 특색, 원료공급처와 제품판매처의 위치, 주위의 지형 그리고 지방정부의 정책에 기인하여 이 공업은 Chittenden Locks와 Portage 만간의 운하지역에 그 입지가 국한되었다. 다시 이 지역내에서는 주위의 지형과 토지이용, 기업의 재정적인 능력 때문에 이 운하지역에 연해있는 기존공장 혹은 건물을 이용하여 입지하게 되었다. 입지후에 이 공업은 원료공급처와 제품판매처와의 강한 linkage를 형성하고 있다. 더구나 원료공급처의 희소성에 기인한 공간적 독점과 소비자 및 제품의 특성 때문에 연구지역의 대부분의 소규모 boat 제조업체는 바로 근처에 있는 원료공급처 및 소비자와 긴밀한 contact를 하고 있고 이러한 contact를 통하여 그들의 입지를 존속시키고 있다. 한편 Seattle 이 가지고 있는 boat 공업에 유리한 기업환경의 덕택으로 이들 소규모 boat 제조업체들은 수요의 계절적인 변동에서 초래되는 노동력의 공급 때문에 곤란을 받을 뿐 장기적인 불황에 직면한 적은 없다. 이리하여 이들 업체들은 이러한 계절적인 변동에 대처하기 위해 생산 input 의 조절, 주위의 기존공장이나 건물의 병합을 통한 연속적인 확장 혹은 그들의 action space 내에 있는 기존공장이나 건물을 이용한 이동등과 같은 입지변화를 보여왔을 뿐이다. 이리하여 연구지역의 소규모 boat공업은 Seattle의 경제 system 내의 주요 subsystem의 하나로서 활발히 움직이고 있다. 그러나 만약 기업의 외부환경에서 초래되는 stress, 즉 주민의 소득저하, 타 recreation 산업이 쇠퇴하게 되면 이 공업 또한 쇠퇴될 것이다. 요컨대 담수 지향성과 관련된 입지상의 특색을 제외하고는 연구지역의 소규모 boat 공업은 타 소규모 공업과 동일한 입지상의 특색을 가지고 있다.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.31-38
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• 2014

Ejector is a simple device which can transport a low-pressure secondary flow by using a high-pressure primary flow. The efficiency of the ejector system is relatively very low, compared to other fluid transport devices driven mainly by the forces acting on the normal direction. However, its major advantage is a simple structure with no moving parts, and it transports a large amount of fluid with a small driving energy. In this study, the performance of side-type liquid ejector commonly used in ships; is analyzed by using experimental and CFD methods under steady and incompressible flow condition by varying the length of the throat and diffuser, the flow pattern and suction phenomenon were studied in detail.

• Journal of Ocean Engineering and Technology
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• v.31 no.3
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• pp.202-207
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• 2017

This paper presents the results of an experimental study on the motions and mooring characteristics of a floating vertical axis wind turbine system. Based on a comparison of regular wave experiment results, the motions of structures with different types of mooring are almost the same. Based on the tension response results of a regular wave experiment with a catenary mooring system, the mooring lines in front of the structure have a larger tension effect than the back of the structure by the drifted offset of the structure. The dynamic response spectrum of the structure in the irregular wave experiments showed no significant differences in response to differences in the mooring system. As a result of the comparison of the tension response spectra, the mooring lines have a larger value with a drifted offset for the structure, as shown in the previous regular wave experiment. The results of the dynamic response of the structure under irregular wave and wind conditions showed that the heave motion response is influenced by the coupled effect with the mooring lines of the surge and pitch motion due to the drifted offset and steady heeling. In addition, the mooring lines in front of the structure have a very large tension force compared to the mooring lines in back of the structure as a result of the drifted offset of the structure.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.4 s.142
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• pp.368-378
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• 2005

The effects of rotary oscillation on the unsteady laminar flow past a circular cylinder. are numerically investigated in the present study. The numerical solutions for the 20 Wavier-Stokes equation are obtained using a finite volume method Tn the framework of an overlapping grid system. The vortex formation behind a circular cylinder and the hydrodynamics of wake flows for different rotary oscillation conditions are analyzed from the results of numerical simulation. The lock-on region is defined as the region that the natural shedding frequency due to the Karmann Vortex shedding and the forcing frequency due to the forced oscillating a cylinder are nearly same, and the quasi-periodic states are observed around that region. At the intersection between lock-on and non-lock-on region the shedding frequency is bifurcated. After the bifurcation, one frequency fellows the forcing frequency($S_f$) and the other returns to the natural shedding frequency($St_0$). in the quasi-periodic states, the variation of magnitudes and relevant phase changes of $C_L$ with forcing phase are examined.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.1
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• pp.1-10
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• 1993

In order to investigate the environmental properties of set net grounds located in the coastal waters of Yeosu, oceanographic observations on the fishing grounds were carried out by the training ship of Yeosu Fisheries University from Jun. 1988 to Dec. 1990. The resultes obtained are summarized as follows; 1) The water mass in the fishing grounds were divided into the inner water (29.50-31.00$\textperthousand$), the mixed water (31.10-32.70$\textperthousand$) and the offshore water (32.70-34.30$\textperthousand$) according to the distribution of salinity from T-S diagram plotted all salinity data observed from Jun. 1988 to Dec. 1990. In spring the mixing water prevailed and in summer the inner and mixing water. But in autumn and winter the mixing and offshore waters prevailed. 2) The inner water which was formed by land water from the river of Somjin and the precipitation in the Yeosu district flowed southerly along the coast of Dolsando and spread south-easterly in the vicinity of Kumodo. The inner water and offshore water which supplied from the vicinity of Sorido and Yokchido formed the thermal front and halofront. 3) As the mixing water flowing from the western sea of Cheju to the southern coast of korea was low in temperature, the water mass of low temperature which appeared at the offshore bottom of Sorido in summer was considered not to be the Tsushima warm current. 4) As vertical mixing was made frequently in spring, autumn and winter, the differences in temperature and salinity between surface and bottom was respectively small. In summer, however, the mixing was not made because of the inner water expanded offshore through the space between surface and 10m layer and so a thermocline of $2.0^{\circ}C$/10m and halocline of 4.0$\textperthousand$/10m respectively in vertical gradient was formed. 5) In the vicinity of Dolsando and Kum a water low in salinity prevailed, but in the vicinity of Namhaedo and YoKchido the reverse took place. The inner and mixing waters formed at these arease was limited to the observation area not to spread widely.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.4
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• pp.29-45
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• 1991

Lip type stern tube sealing systems have used in almost all the middle or large ships which are being constructed in these days. It seems that the pressure fluctuation of the seal ring interspace, the cross-section profile and the materials quality of the seal rings have great effects on the sealing fuction of this sealing system. In this paper, the mechanical movement of lip seal ring which plays the most important role in stern tube sealing system and the possibility of leakage caused by pressure fluctuation are studied by theory and experiment. Using the finite element method for the axi-symetric object which receives the torsional load, the displacement and stress analysis of the seal rings, and also the possibility of crack occurance is checked by theoretical analysis. If the force which seal ring lip periphery receives is too small, there will be the possibility of leakage caused by the pressure fluctuation of the seal ring interspace, and if this force is too large, the frictional force between the seal ring and the liner will become problematical. The possibility of leakage caused by hardening of seal ring materials and creep phenomena of tested seal rings are also examined. The trial seal rings were designed and manufactured using the program of displacement and stress analysis developed in this study and the experimental apparatus to test the trial seal rings was also designed and manufactured. This trial seal rings were fitted in the experimental apparatus which was made in the same form as an actual stern tube. The one side of this apparatus was filled with sea water and the other side of it was filled with the lubricating oil. The leakage of oil and sea water was checked and the temperature was measured, rotating the propeller shaft at the constant velocity by D.C. motor. It was proved that the trial seal rings made in Viton rubber functioned excellenty but the trial seal rings made in N.B.R. rubber had problem in its durability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.293-299
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• 2012

The thermodynamic efficiency characteristics of R245fa and water as working fluids have been analyzed for the electricity generation system applying the Rankine cycle to recover the waste heat of the exhaust gas from a diesel engine for the propulsion of a large ship. The theoretical calculation results showed that the cycle, system, and total efficiencies were improved as the turbine inlet pressure was increased for R245fa at a fixed mass flow rate. In addition, the net work rate generated by the Rankine cycle was elevated with increasing turbine inlet pressure. In the case of water, however, the maximum system efficiencies were demonstrated at relatively small ratios of mass flow rate and turbine inlet pressure, respectively, compared to those of R245fa. The optimized values of the net power of the cycle, system efficiency, and total efficiency for water had relatively large values compared to those of R245fa.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.1
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• pp.46-58
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• 1997

The energy saving is one of the most important factors for profit in marine transportation. In order to reduce the fuel oil consumtion the ship's propulsion efficiency must be increased as possible. The propulsion efficiency depends upon a combination of an engine and a propeller. The propeller has better efficiency as lower rotational speed. This situation led the engine manufacturers to design the engine that has low speed, long stroke and a small number of cylinders. Consequently, the variation of rotational torque became larger than before because of the longer delay-time in fuel oil injection process and an increased output per cylinder. As this new trends the conventional mechanical-hydrualic governors for engine speed control have been replaced by digital speed controllers which adopted the PID control or the optimal control algorithm. But these control algorithms have not enough robustness to suppress the variation of the delay-time and the parameter perturbation. In this paper we consider the delay-time and the perturbation of engine parameters as the modeling uncetainties. Next we design the robust servo controller which has zero offset in steady state engine speed, based on H sub($\infty$) control theory. The validity of the controller was investigated through the response simulation. We used a personal computer and an analog computer as the digital controller and the engine (plant) part respectively. And, we could certify that the designed controller maintains its robust servo performance even though the engine parameters may vary.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.340-341
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• 2007

In case of Busan Port container terminals scale of a yard device chapter is small and narrow, and redundant works of device chapter facilities ability and transfer cranes are misgovernment occurring very much bemuse of this There is to the misgovernment that cannot support design ability of a container crane of quay because of this There is this in a change of marine transportation harbor environment to cross over to a large easel next of a ship, and a large problem cannot but become. Watched how redundant works were occurring in the second yards, and presented a problem Also, present the hint point tint these redundant works analyze how productivity of quay productivity and container crane is improved if solution works, and face to this.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.1
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• pp.47-52
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• 2013

The higher energy efficiency for ship and the lower pollution for global environment are required strictly. However the performance of marine diesel engine is gradually deteriorated with time. And also the operation condition is varied with sea conditions. Hence the optimization for operating condition of marine engines is needed for energy saving and environment kindly. In this paper, it was attempted to investigate the influence of aging for marine diesel engine. The deterioration of engine performance is assessed by the calculation results of the simulation program for two-stroke marine diesel engine developed by author which was reported before. And three parameters for deterioration of engine performance were considered such as lower efficiency of turbocharger by fouling, increase of blow-by gas due to wear of cylinder liner and getting worse of combustion by poor injection. By the results, it was shown that the influence of engine performance by aging was relatively not so small - 10.4 bar low in Pmax and 3.2% decrease in Pmi.