• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.395-402
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• 2005

The most important point when we engage on waterway dredging work is supplying safe navigational passage to the vessels underway by narrowing dredge work area and removing submerged dangers. In order to meet this end it is necessary to use auxiliary equipment for shifting actively and mooring and adopt automation of dredging work by integrating information on real time position, dredging depth, and work information. The dredger with a spud control system in this study, by the way, is able to employed on continuous dredging work with the narrowest working area allowing wide and safe passages to vessels underway, by moving the dredger to the working zone with the spud controlled automatically. Furthermore, it has been improved definitely compared with the existing dredging process management system such that it shows the track of spud and working depth on the electronic navigation chart of window, together with the final outcome of dredging work. The test dredging work at the entrance of Busan North Port for system evaluation showed that actual working time available was twice of the one by the existing anchor system, and that it reduced $38\%$ of time for preparation work and one man power.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.345-351
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• 2015

This study investigated the optimum depth for the application of bioremediation in contaminated coastal sediment using a lab scale column experiment. The biostimulants were placed in the top surface of the sediment facing seawater, 3cm, 6cm and 10cm of the depth from the surface, respectibely. During the experiment, the changes of organic pollutants and heavy metal fractions in the sediment were monitored in 1 month and 3month time intervals. The organic pollutants found during various analysis such as chemical oxygen demand, total solids and volatile solids, significantly reduced when the depth of the biostimulant was 3cm or less. In contrast, at a depth of over 6cm, the reduction of organic pollutants decreased, and the results were similar to the control. Heavy metals fractions in the sediment also changed with the depth of the biostimulants. The exchangeable fraction of the metals was quite reduced at the sediment surface in the column, but the organic bound and residual fractions considerably increased at a depth of 3cm. Based on this study, the optimum biostimulants depth for in-situ bioremediation of contaminant coastal sediment is 3cm from the sediment surface.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2109-2116
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• 2014

This paper presents the implementation and design of the advanced WI-FI systems with beam-forming antenna that radiate their power to the direction of user equipment to improve the overall throughput, contrast to the general WI-FI systems equipped with omni-antenna. The system consists of patch array antenna, DSP, FPGA, and Qualcomm's commercial chip. The beam-forming system on the FPGA utilizes the packet information from Qualcomm's commercial chip to control the phase shifters and attenuators of the patch array antenna. The PCI express interface has been used to maximize the communication speed between DSP and FPGA. The directions of arrival of users are managed using the database, and each user is distinguished by the MAC address given from the packet information. When the system wants to transmit a packet to one user, it forms beams to the direction of arrival of the corresponding user stored in the database to maximize the throughput. Directions of arrival of users are estimated using the received preamble in the packet to make its SINR as high as possible. The proposed beam-forming system was implemented using an FPGA and Qualcommm's commercial chip together. The implemented system showed considerable throughput improvement over the existing general AP system with omni-directional antenna in the multi-user communication environment.

• Journal of the Korean Institute of Gas
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• v.2 no.2
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• pp.48-54
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• 1998

In this study a computerized prototype system was developed with Safety Management Information System(SMIS version 1.0) as a main system and database as subsystems to handle information. Safety management information consists of management aspects and technical elements, but SMIS consists of 4 modules of technical elements to interrelate safety technologies closely. SMIS enables gas industries to manage process safety information effectively and to evaluate hazards. The results from SMIS can be used to the operation manual and the emergency plan. Data base consists of 3 modules of accident data, material data, and equipment data to support SMIS. Also, the case study results proved the usefulness of SMIS for searching and accumulating process safety data. Especially, MIS which has the database suggests a formal structure for scattered raw safety data in gas industries and brings reduction of man power and time.

• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.305-312
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• 2017

In our society, the advanced, advanced, and information industries have continued to grow and now live in the era of the fourth industrial revolution. As the industry develops, the load of the users has also increased so much that it is deepened by the energy shortage phenomenon and the construction of additional energy facilities is required. Therefore, energy plant construction work is being actively carried out in the coastal area. In particular, it is common to build a plant in the ground by filling the coast with soil in other regions, reflecting the fact that Korea is lacking in the country when constructing power plants, gas and petrochemical plants. Current domestic grounding designs are designed or constructed to suit only the use of grounding resistors based on the electrical equipment design technical standards. However, in the case of a plant facility constructed in the untested buried soil, when the lightning current and the abnormal current are inputted, the facility operator or the user due to the elevation of the ground potential is seriously exposed to the risk of electric shock disaster. In this paper, we analyze the ground resistivity of the landfilled soil and use a computer program (CDEGS) based on KS C IEC 61936-1, We analyze the contact voltage and stratification voltage and propose a grounding design optimized for plant installation.

• Korean Security Journal
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• no.42
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• pp.205-227
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• 2015

The Korean Peninsula is put in a position to carry out a highly strategic game vis-a-vis nK, which is asserting itself as a nuclear power amongst Northeast Asia's complex dynamics. While the international community recognizes nK's possession of nuclear weapons as released secret based on nK's three nuclear tests, shrewd strategic thinking is needed by ROK to secure itself as a non-nuclear nation in order to assume a responsible role to the international community, while simultaneously being ready to respond at all times for nK's military provocations. ROK must continue with its twofold strategy, by firm response to military confrontation with nK and maintaining flexible policy of tolerance in the areas of economy and ethnicity. Various strategic options to overcome nK's nuclear threats have been presented to ROK, whose possession of nuclear weapons have been difficult, and nK's nuclear capability is a real threat to ROK's national security. We must be able to respond to nK's nuclear threats strictly from ROK's national security perspective. This thesis aims to propose a response policy for nK's nuclear capability and nK's nuclear attack based on analysis of such nuclear damage, ROK Government's response posture against nK's nuclear threats, centered around ROK Government's non-military response posture.

• The Korean Journal of Health Service Management
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• v.3 no.1
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• pp.14-24
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• 2009

This study aims at deriving any useful information necessary to strengthen the competitiveness for growth through empirical analyses on general hospital located in a province in order to countermeasure the opening and competition of medical markets. The characteristics of user were identified on the basis of disease groups under KCD in the research method. In addition, the analysis on the expenses of diagnosis and treatment was divided into the treatment progress and degree of hospital resource utilization And the regression was carried out to identify the impacts of characteristics of inpatient users on the degree of hospital resource utilization. As a result of major research, the inpatient users of the general hospital located in the provincial area in consideration of inpatient users were formed around the inpatient disease groups representative for Korea(diseases of the respiratory system, injury and poisoning & certain other consequences of external causes). And it was understood that most of residents within a distance of 40 minute by the public transportation were using. And mostly were under the age of 9 or over 60, and the provision of medical features such as the degree of consultation and operational functions were inadequate. When we classify inpatient treatment cost for each resource application as the medical cost being the center of patient care function, the equipment and human resource application sector are constituted over half. Accordingly, the following suggestions are made as plans to strengthen the competitiveness for the growth of general hospitals located in the provincial areas on the basis of analytical results. First, it is necessary to have the characterization matching to the age and disease groups with a high frequency. Second, it is necessary to increase the degree of hospital resource utilization according to the characterization. Third, it is necessary to concentrate on public relations. The above suggestion, as a method for securing image improvement and competitive power as a general hospital, and through expansion of social function that a regional general hospital needs to secure not only as an individual institution but also as a general hospital, it can be seen that a general improvement of image as a regional general hospital is possible.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.1
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• pp.183-194
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• 2004

It's essential process to study non-linear material function related to characteristics of compressibility and permeability when we predict the consolidation behavior of soft clay ground. In this study, laboratory tests were conducted to find out the material function using marine clay. Standard oedometer test and Rowe cell test were performed with conditions, which were classified into vertical drainage only, radial drainage only and vertical-radial drainage case. Modified oedometer test equipment was developed to find out the material function and special extrusion device was originated to minimize the sample disturbance effect. Reliability of the results in modified oedometer test could be confirmed by comparing with the Rowe cell's one. Effective stress - void ratio - permeability relations were analyzed using all testing results. As a result, void ratio with effective stress level could be expressed by the power function and permeability with void ratio could be expressed by exponential function. In soft clay with high initial water content and low shear strength, non-linear characteristics related to compressibility and permeability varied with wide range by the effective stress levels. It's important to note that non-linearity of the material function should be considered at prediction of the consolidation behavior.

• Journal of Drive and Control
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• v.13 no.2
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• pp.10-18
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• 2016

A front-end loader (FEL) mounted on an agricultural tractor is one of the most commonly used implements to mechanize routine agricultural tasks. When the FEL is used with a loaded bucket, careful operation is required to maintain safety and avoid spillage when the tractor passes a bump because a change in the gravity center of the tractor due to varied loadings can affect the stability of the tractor. Use of a boom suspension system consisting of accumulators and orifice dampers can be instrumental in reducing pitching vibrations while increasing the handling performance of the FEL-mounted tractor. The objective of this research was to reduce bump shocks by adding an orifice and a flow control valve to the original hydraulic circuit composed solely of accumulators. A simulation study was performed using the SimulationX program to investigate the effects of an accumulator and an orifice-throttle damper on bump shocks. Results showed that the peak pressure on a boom cylinder and the vertical acceleration of a bucket were significantly affected by use of both an accumulator and an orifice damper. In a field test conducted with a 75-kW tractor, the peak pressure of the boom cylinder, and the root mean square (RMS) vertical acceleration of the bucket and seat were reduced by on average, 23.0, 42.2, and 44.9% respectively, as compared to those measured with the original accumulator system, showing that an improved design for the accumulator hydraulic circuit can reduce bump shocks. Further studies are needed to design a tractor suspension system that includes the effects of cabin suspension and tires as well as dynamic analysis.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.147-153
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• 2016

The lightning protection of information and communication facilities is very important factor to improve a reliability of the action of these equipment. Especially the transient potential rise of ground electrode being injected with the lightning current is to be a basic data of the dielectric strength for both power and communication facilities so that more accurate analysis should be required. The transient potential rise can be calculated from the ground impedance and the ground impedance is strongly dependent upon the shape of the ground electrode and the frequency-dependence of soil. The Debye's equation which is able to calculate the characteristics of dielectrics is used to analyze the frequency-dependent of soil. Also, the method to calculate the transient potential rise from the ground impedance is specified in this paper. In order to analyze the transient potential rise resulting from calculations with Debye's equation, TLM(transmission line method) and case of ${\rho}$(resistivity)-constant are simulated, respectively. The length of a horizontal ground electrode is 30 m and simulations were performed at 10, 100, $1000{\Omega}{\cdot}m$ with the standard lightning current waveform. In result, the transient potential rise of horizontal ground electrode calculating with Debye's equation is lower than it of other models.