• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.65-65
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• 2016

Various types of flow conditions are developed in the region just downstream of hydraulic structures such as weir and drop structures. One of distinct flow conditions occurred downstream of drop structures is the wave type flow with undular hydraulic jump formation. We present three-dimensional numerical simulations of a wave type flow formed downstream of a stepped weir which were experimentally investigated by Kang et al. (2010). The turbulent flow over the weir structure is modeling using the unsteady Reynolds-averaged Navier-Stokes (URANS) simulation employing the Spalart-Allmaras one equation model and the detached eddy simulation. Numerical modeling and the performance of turbulence modeling approaches are evaluated by comparing with the experimental measurements in terms of the free surface variation, the shapes and sizes of undular wave, roller near at free surface, recirculation zone near the channel bottom downstream of the structures, and streamwise velocity profiles at selected longitudinal locations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.11
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• pp.1397-1405
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• 2013

The optimal rib pattern design of B-pillar trim considering occupant head protection can be determined by two methods. One is the conventional approximate optimization method that uses the statistical design of experiments (DOE) and response surface method (RSM). Generally, approximated optimum results are obtained through the iterative process by trial-and-error. The quality of results strongly depends on the factors and levels assigned by a designer. The other is a methodology derived from previous work by the authors, called the sequential design of experiments (SDOE), to reduce the trial-and-error procedure and to find an appropriate condition for using artificial neural network (ANN) systematically. An appropriate condition is determined from the iterative process based on the analysis of means. With this new technique and ANN, it is possible to find an optimum design accurately and efficiently.

• The Korean Journal of Archival Studies
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• no.65
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• pp.253-319
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• 2020

Hongdong Herstory in an narrative-based archival activities. This Herstory Workshop designed by a facilitator who is using her love for language and storytelling to empower all voices. Herstory Workshop has been opened at winter every year for a month. The place where the workshop opened is located at farming area. Hongdong Herstory Workshop has been the field where the members of the community having a talk together. 20 women have been participated at the Herstory Workshop. Herstory projects have been published every year. This essay is an trial for rearchiving the herstory projects. This essay focused on the narrative function of archives.

• Journal of Advanced Navigation Technology
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• v.26 no.2
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• pp.105-112
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• 2022

In this paper, unmanned underwater glider was designed for high-depth operation and adopted a bladder-type buoyancy controller for improving battery efficiency, and the motion controller controls the pitch angle by moving the internal mass battery. To improve the energy efficiency of the unmanned underwater glider, a layered PID controller that performs control by section was designed. Simulation program including 6-DOF motion equations and hydrodynamics coefficients of an unmanned underwater glider is constructed using Matlab/Simulink program. Control methods such as PID controller, sliding mode controller and layered PID controller were applied to the simulator to compare the dynamics performance and energy efficiency. As a result, the layered PID controller showed improved control performance compared to other controllers and improved energy efficiency of approximately 7.2% compared to PID controller.

• Korea Trade Review
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• v.43 no.3
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• pp.47-74
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• 2018

The United States is often perceived as a free-trading nation as it significantly contributed to the establishment of the GATT and WTO in the 20th century. With the inauguration of the Trump Administration in 2017, however, trading partners of the United States are faced with great concerns over the 'new' aggressive, protectionist and above all, unilateral trade threats posed by the United States under the name of 'America-First' trade policy. However, the recent unilateral trade actions by the United States are not new, but has historically and continuously been used to protect its key industries, like the automobile sector. This paper analyzes the historical cases of the unilateral trade policy of the United States in the automobile industry, targeting Korea and Japan in the 1980s, 1990s and 2010s. Then, we draw future implications for other key industries of the United States such as IT, intellectual property, services and agricultural sectors. This study evaluates whether such unilateral practices have brought successful and expected outcomes in favor of the United States.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.1
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• pp.37-48
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• 2021

A new high speed rotation type-passive sampling device (HSR-PSD), which can rotate seawater at high speed and absorb easily and quickly the freely dissolved hydrophobic organic contaminants from seawater, was developed and then applied around the Korean Peninsula. Freely dissolved concentrations (Cfree) of polycyclic aromatic hydrocarbons (PAHs) were determined using the HSR-PSD with low density polyethylene (LDPE) sheets as a passive sampler. Furthermore, dissolved concentrations (Cdissolved) of PAHs in seawater were also obtained from high volume water sampling as a conventional method to account for actual bioavailability. When the LDPE sheets were rotated in the HSR-PSD at 900 rpm, PAHs with log KOW 3.4 ~ 5.2 were equilibrated between the LDPE and water in 5 hours. Although the high molecular weight PAHs with log KOW 5.6 ~ 6.8 was expected to be 2 to 30 days to reach the equilibrium, the Cfree of the PAHs at equilibrium could be corrected using performance reference compounds in 5 hours. Meanwhile, the total Cfree of PAHs were from 0.32 to 1.2 ng/L, which were higher than reported values in other oceans, but lower than in coastal water such as estuary, harbor, or shore. A bioavailability from the detected PAHs was highest at the sampling line near the dumping site of the Yellow Sea. Predicted residual concentrations in biota were relatively higher in offshore including the dumping site than in coastal regions.

• Journal of Korea Port Economic Association
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• v.26 no.1
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• pp.195-221
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• 2010

Kunsan port based on the selection of Kunsan Free Trade Area is expected to develop into a regional beach-head port and foreign investment area, and as the result it will play a great role in accelerating the coming age of the west sea. To promote the foreign competitiveness of Kunsan port as a central container port it can be pointed out that 1) to raise up the utilization ratio of Kunsan port as the front base of export and import by multinational corporations, 2) to hustle up the development of Kunsan container port toplay the central role as the composite container linkage central port, 3) to strengthen the attraction activities of foreign investment into the Kunsan Free Trade Area for the balanced development between regions in nation, 4) the support of both central and local governments to accelerate the comingage of the west sea are necessary.

• Journal of Information Management
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• v.35 no.3
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• pp.139-159
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• 2004

Digital library technology is facing issues such as interoperability, content extension, and the need for a more efficient management environment. A system that is based on standardization and interoperability is required to resolve these issues. Open Digital Library is the system for the next generation that resolves the above problems. We have conducted some research on issues such as OAI and OAI-PMH, which are the basic knowledge behind the Open Digital Library technology and also investigated the Open Digital Library framework, cases of study and implementation of this technology. Finally, we have made some suggestions on the extendability of Open Digital Library technology using the standardized technologies.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.4
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• pp.230-240
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• 2020

The aim of this study was to investigate the manoeuvrability of a ship in different Center of Gravity (CG) conditions. Free Running Model Tests (FRMT), such as 35°turning circle tests, 20/20 zigzag manoeuvring tests, and 10/10 zigzag manoeuvring tests, were conducted in three GM and three trim conditions with 1/65.83 scaled KRISO Container Ship (KCS). The test results indicated that KCS in the lower GM condition and the trim by bow condition showed reduced advance and tactical diameter in turning circle tests and increased overshoot angles in zigzag tests, and those manoeuvring indices were strongly related with roll angle. In addition, sensitivity indices for three-axis CG position were suggested with prior research, and it showed that y-axis CG position significantly affected manoeuvrability of KCS due to the low GM. Therefore, in the case of KCS, it is evident that the roll angle during manoeuvre is closely related with manoeuvring indices.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.83-85
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• 2015

The Purpose of this paper was to carry out basic study on development of real-time submarine-hnadling simulator. The author adopt the Unmanned Undersea vehicle(UUV), which has taken the shape of manta[1]. They call here it Unmanned Undersea Vehicle(UUV). UUV is based on the same design concept as UUV called Manta Test Vehicle, which was originally built by the Naval Undersea Warfare Center, USA[1]. The present study deals with prediction of manoeuvring motion of UUV at general drift angles and large drift angles. The dynamic mathematical model with six degrees of freedom is revised and supplemented in order to describe accurately motion of UUV. The hydrodynamic derivatives related to motion are obtained from previous work[2].