• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2661-2667
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• 2013

Recently, at Home and abroad, Internet of Things era things(Thing) is participating as a subject of communication in human communication paradigm of existing (lot/M2M) is in full swing. Automobile, refrigerator, bicycle, until shoes, and communication functions generation of information is installed and has created a fusion of new service IT infrastructure. Its use and application are broadening to various areas and the number of devices used for it is increasing to increase the number of information transmitted for each object. When the traffic reaches its limit while each set of data is transmitted from the devices divided into each group through the mobile network, M2M communications service might not be processed smoothly. This study used the Knapsack Problem algorithm to create a virtual simulator for a smooth M2M service when the mobile network used for the M2M communications reaches its limit. The virtual simulator applies smooth processing of services from the M2M communications that should be processed first to other subsequent services when data comes to each group of devices. As the M2M technology develops to make many objects more compact in size, it would help with smoother processing of M2M services for the mobile network with fast-increasing traffic.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.189-195
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• 2017

The only method used in the power stations in order to deliver generated electric power is 6 kV XLPE (or CV) single core cables. Among many kinds of accidents happening in the power stations, the outbreak of fire due to the deterioration of live cables causes enormous socioeconomic losses. From the installation of the cables, the management and diagnose should be thoroughly made. Even though it differs depending on the installations and usage conditions, the cross-sectional area of cables is in shortage. The excessive allowable temperature caused from the current causes the deterioration of cables. In order to prevent an unexpected breakdown of live cables, we have invented a device to monitor and diagnose the status of cables. We have installed our device in the Korea Western Power Co., Ltd.. In this paper, we present our research results in situ that we have obtained by measuring the temperature of sheath, changing with the surrounding circumstances, especially ambient temperatures. We also show our study results of characteristics for temperature of sheath surface and load current at the ambient temperatures of $40^{\circ}C-10^{\circ}C$.

• Journal of agricultural medicine and community health
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• v.16 no.2
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• pp.97-119
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• 1991

Korea has made a rapid economic development since the last three decades. This has helped Korea narrow the gap in health service differences in resource availability and in quality of care. However urban and rural differentials are still remarkable. This study has maintained that health status of rural residents is inferior to that of urban dwellers. Therefore, this study was carried out to develop policy measures for improving health services in rural areas. In order to achieve the objective of this study the authors collaborated closely and made field visits, interviews and conducted an extensive literature review regarding rural health services. The following policy options are recommended as a summary ; First, the quality of rural health personnel is a single most important factor influencing the level of rural health services. An innovative program for public health doctors to the internship and/or residency training program such as specialty board program of family medicine. Second, dissatisfaction regarding employment of public health doctors is problematic. More rational employment and deployment programs are needed to meet their personal desire. One way to do this is to make it wide open and competitive. Third this study shows how to increase physician productivity in the rural public health sector. Incentive system needs to be elaborated for the career development of rural health workers. University linked job opportunity as clinical professor is an example. Fourth, without straightening the function of health centers and subcenters, the future of rural health services is doomed to failure. Straightening primary health care is one way to enrich the program of public health facilities and reactivating the operation of health center/hospital is another. A close linkage of public facilities with private hospitals is a minimum requirement for the operation of health delivery system within a health district. Fifth, some measures are urgently required to enhance hospital services in medically underserved areas. Financial subsidy, tax exemption, long-term public loans and higher priority of health manpower deployment are some of them. Sixth, new health programs should be in tiated to meet changing needs of peoples in rural areas. Home health care program, hospice program, nursing home, residential program for the elderly are recommended.

• Journal of the Korean Geotechnical Society
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• v.29 no.3
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• pp.51-60
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• 2013

The slime, deposited in the bored pile due to falling soil particle, reduces the bearing capacity of bored pile and thus the stability of construction also decreases. The weight pendulum and iron have been used for estimating the slime thickness based on the subjective judgment and thus the previous method has a limitation of reliability. The objective of this paper is to suggest the method for estimating the slime thickness by using characteristics of electrical resistivity as scientific method. The temperature-compensation resistivity probe (TRP), which has a conical shape and the diameter of 35.7mm, is applied to the measurement of the electrical resistivity in the borehole during penetration. The field tests are carried out for estimating the slime thickness in the application site of bored pile. The slime thickness is calculated through the difference between excavation depth of borehole and measured data. Furthermore, the laboratory tests are also conducted for investigating effects of casing, time elapsing and relative density by using the specimen of slime. The laboratory test supporting the suggested method is reasonable for determining the slime depth. The paper suggests that the electrical resistivity method may be a useful method for detecting slime thickness and the method is expected to be applicable to various sites of bored piles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.739-744
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• 2017

Elastic deformation and fatigue damage can cause the permanent deformation of a kart's frame during turning, affecting the kart's driving performance. A kart's frame does not contain any suspension or differential devices and, therefore, the dynamic behavior caused by torsional deformation when driving along a curve can strongly affect these two kinds of deformations. To analyze the dynamic behavior of a kart along a curved section, the GPS trajectory of the kart is obtained and the torsional stress acting on the kart-frame is measured in real time. The mechanical properties of leisure and racing karts are investigated by analyzing their material properties and conducting a tensile test. The torsional stress concentration and frame distortion are investigated through a stress analysis of the frame on the basis of the obtained results. Leisure and racing karts are tested in each driving condition using driving analysis equipment. The behavior of a kart when being driven along a curved section is investigated through this test. Because load movement occurs owing to centrifugal force when driving along a curve, torsional stress acts on the kart's steel frame. In the case of a leisure kart, the maximum torsional stress derived from the torsional fatigue limit was found to be 230 MPa, and the torsional fatigue limit coefficient was 0.65 when driving at a speed of 40 km/h. Furthermore, the driving elements during the cornering of a kart were measured based on an actual auto-test after installing a driving measurement system, and the driving behavior of the kart was analyzed by measuring its vertical displacement.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.11
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• pp.1515-1522
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• 2008

Monitoring the pesticide residues in agricultural products is essential to protect consumers, obtain data for risk assessment, and ensure fair trade practices. We developed a multi-residue method for the analysis of 37 pesticides with different physico-chemical properties in agricultural products and analyzed the amount of pesticide residues on about 1,000 samples circulated in South Korea. The samples consisted of 26 different types of agricultural products selected at markets in 14 major cities; cereals (2 species), nuts (1 species) potatoes (1 species), beans (2 species), fruits (3 species), vegetables (16 species), and mushrooms (1 species). In this study, residual pesticides were detected in 23 samples (2.2%) and one sample was detected to be over maximum residue limits (MRLs, 0.1%) for pesticides in foods by the Korea food code. In leafy vegetables such as pepper leaves, radish leaves, cham-na-mul, shin-sun-cho, crown daisy, chwi-na-mul and citrus fruits such as kumquat, 8 kinds of pesticides were detected. Specially, diazinon were detected over MRLs and also, endosulfan, ethoprophos and phenthoate were detected frequently. Based on these results, we investigated the risk assesment from amount of residual pesticide, total %ADI was 1.262%, but the value has not effected on human health.

• Journal of Navigation and Port Research
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• v.39 no.1
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• pp.23-28
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• 2015

This paper is to identify the dynamic phenomenon of the marine pollution management that is connected directly or indirectly by using system dynamics analysis. The method used herein is based on system dynamics analysis that analyzed the sub-systems for marine pollution management. Furthermore designed feedback loop between system elements. And made total casual map of marine pollution management. The main results of the paper are the following : 1. It's necessary to equipments and technology development and law revision for feedback loop slump of initial measures delay in oil spill. 2. It should be come up with partnerships and new business for community corrosion non-proliferation caused by social conflicts. 3. Marine pollution management should be an obligation that must be minimized to include social conflicts in the community and national levels besides oil spill response on-site. This model confirmed the hidden cause of delay by existing response plans, manuals and programs. And oil spill response in broader sense is more important from now on. The result can be useful in the guidance of marine pollution and management.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.655-662
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• 2016

This study proposes that a diving supervisor, who can perform the role of both a field manager and a supervisor, be introduced in the national qualification system. The goal was achieved by surveying the general status of the commercial diving sector, including the statistics of an underwater construction company, commercial diving equipment operation condition, diver working hours, diver supply and demand status, and underwater construction market size. The national qualification and national competency standard (NCS) systems were also analyzed to deduce the role definition and work scope of the diving supervisor. Consequently, the following proposition is made: the diving supervisor should be an "on-site manager with the highest job skill in the commercial diving field, who can perform the on-site process management as well as guide, supervise, and educate project participants and serve as an intermediary between the contractor and the workers." The responsibilities of the diving supervisor are proposed to include "diving planning and operation of the diving team," "diving with surface-supplied air and mixed-gas diving system," "chamber operation," "underwater construction," and "ship salvage." The persistent issues in commercial diving sectors, such as diver career development, management, and worker supervision, are expected to be largely resolved with the introduction of this qualification.

• Journal of Internet of Things and Convergence
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• v.6 no.3
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• pp.75-80
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• 2020

Recently, the size of the IoT sensor has been decreased and the collecting direction of the IoT sensor for acquiring the data have been changed from 2D to 3D. It makes sensor structure complex. In the fabrication of the complex structure, 3D printing technology has more useful than traditional manufacturing technologies. Among 3D printing technologies, FDM (fused deposition modeling) is a candidate technology to fabricate a small IoT sensor because the price of the machine and the material is cheap. In the FDM process, a 3D shape is made by depositing the melted filament. Recently, the patent of FDM technology is expired and cheat machines are developed based on the open-source. In the FDM process, mechanical properties of a fabricated part is affected by a lots of factors such as the kind of material and process parameters. Among them, infill is affecting the mechanical properties and the production lead time as well. In this work, a new method to optimize the FDM process with the consideration of mechanical property and production lead time was proposed. To verify the method, the fabrications were performed with the different infill rates. The results of tensile tests were analyzed to verify the proposed method.

• Economic and Environmental Geology
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• v.43 no.2
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• pp.177-184
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• 2010

When cement grout is used for waterproofing of grounds, important roles are played by fluidity, particle size and bleeding. The most important element which determines their characteristics is the water/cement ratio of grout. Moreover in order to improve the efficiency of soil permeation, micro cement with a smaller average diameter is used in addition to ordinary portland cement. Besides the mixing ratio and cement diameter, the condition of ground is also of fundamental importance in the efficiency of permeation. In order to evaluate grout in terms of permeation ability into ground, we need a field test of grounting, which is cost and time consuming. In this paper we present a laboratory test method in which the suitability and efficiency of grouts are simply and more practically tested. In Korea neither a test standard nor devices are available to simulate grouting in a laboratory. We devised a grout injection equipment in which grouting was reproduced in the same condition with different materials, and suggested a standard for the production of specimens. Our tests revealed that the efficiency of injection increases with the water/cement ratio. We also found that more efficiently injected is the grout with the order of decreasing size; MS8000, micro cement, and ultra fine cements, and colloidal super cement.