• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.317-318
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• 2006

A transfer loading system for 21' RF band assembly box was developed in the present study. The weight of a box is approximately 60kgf End total weight of one day job per person is about $4,000kg_f$. For an efficient design and manufacturing process, three dimensional design and engineering technique were applied to the presented system. Motion analysis for a popup unit and structural analysis for belt part subjected to the load of box weight were performed, respectively. It was found that the evasion of duty and labor intensity is reduced after appling the developed system to manufacturing field of small and midium business.

• Journal of the Korea Safety Management & Science
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• v.4 no.4
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• pp.87-95
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• 2002

우리나라 기업 물류비는 다른 나라에 비하여 상당히 높다. 따라서 대표적인 기업인 "P" 사를 통하여 기업 물류비를 절감하는 사례를 연구코자 한다. 우선 "P" 사에 PPS(Pallet Pool System)를 도입하기 위하여 납품되는 원부자재를 Unit Load System화 하고 물류 모듈(Module)체계를 확립, 일관파렛트화하여 Pallet Pool System을 도입, 기업물류비를 절감하는 사례이다. 개선 전에는 협력업체에서 1회용 목재 파렛트에 원부자재를 납품하면 "P" 사에서 원부자재 사용 후 폐기하는 System으로 물류비 소모가 많았다. 그러나 PPS 도입으로 협력업체는 물류비를 년간 17.6억원 을 절감하였고, "P" 사는 PPS에 활용되는 STEEL 파렛트에 따른 년 3,600톤의 철강 대체효과를 이루었다. 또한 "P" 사는 1회용 목재파렛트 폐기 비용을 절감하고, 청결한 기업환경을 조성하였으며, 물류비를 절감하여, 기업 이윤을 확대하고 기업경쟁력을 강화시키는데 기여하였다조성하였으며, 물류비를 절감하여, 기업 이윤을 확대하고 기업경쟁력을 강화시키는데 기여하였다

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1145-1151
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• 2022

A hybrid cutting using both plasma and end mill was developed for safe and efficient dismantling of nuclear facilities. In this cutting method, a moving arc plasma heats up the workpiece before milling. Thermally softened part of the workpiece is then removed quickly and deeply with an end mill. For the cutting experiments, a three-axis numerical control (NC) milling machine was combined with a commercialized arc plasma torch and used to cut 25 mm thick stainless steel plates. Experimental results revealed that pre-heating by arc plasmas can improve the cutting volume per unit time higher than 40% by reducing the cutting load and increasing the cuttable depth when using an end mill without cutting fluids. These advantages of a hybrid cutting process are expected to contribute to quick and safe segmentations of metal structures with radioactively contaminated inner surfaces.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.653-664
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• 2015

TPLMS (Total water pollutant load management system) that is the most powerful water-quality protection program have been implemented since 2004. In the implementation of TPLMS, target water-quality and permissible discharged load from each unit watershed can be decided by water-quality modeling. And NPS (Non-point sources) discharge coefficients associated with certain (standard) flow are used on estimation of input data for model. National Institute of Environmental Research (NIER) recommend NPS discharge coefficients as 0.15 (Q₂₇₅) and 0.50 (Q₁₈₅) in common for whole watershed in Korea. But, uniform coefficient is difficult to reflect various NPS characteristics of individual watershed. Monthly NPS discharge coefficients were predicted and estimated using surface flow and water-quality from HSPF watershed model in this study. Those coefficients were plotted in flow duration curve of study area (Palger stream and Geumho C watershed) with monthly average flow. Linear regression analysis was performed about NPS discharge coefficients of BOD, T-N and T-P associated with flow, and R² of regression were distributed in 0.893~0.930 (Palger stream) and 0.939~0.959 (Geumho C). NPS Discharge coefficient through regression can be estimated flexibly according to flow, and be considered characteristics of watershed with watershed model.

• Korean Journal of Construction Engineering and Management
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• v.19 no.3
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• pp.70-78
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• 2018

Due to the increasing concern about climate change, efforts to reduce environmental load are continuously being made in construction industry, and life cycle assessment (LCA) is being presented as an effective method to assess environmental load. Since LCA requires information on construction quantity used for environmental load estimation, however, it is not being utilized in the environmental review at the initial design stage where it is difficult to obtain such information. In this study, a construction quantity computation system based on the standard section was developed for the drainage facilities of the road and utilized in the model to calculate the environmental load. This model can estimate the environmental load by calculating the amount of resources required for LCA using only the information available at the initial design stage. To verify the validity of the model, five validation cases were applied and compared with the unit estimation model and the multiple regression analysis model. As a result, it is confirmed that the mean absolute error rate is 9.94%, which is relatively accurate and effective model in the initial design stage.

• Journal of Environmental Impact Assessment
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• v.28 no.6
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• pp.536-548
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• 2019

In order to quantify the effect of the newly established the Total Water Load Management System in Sapgyo watershed, this study predicted the achievement of the target water quality at each unit watershed and the water quality according to the flow section. The HSPF model, which is the watershed runoff model, was constructed and operated based on 2015, and the water quality was predicted by inputting the loads in final target year(2030). The Load Duration Curve (LDC) was created using the simulated results of base year and target year. As a result of plotting water quality by flow conditions, it was simulated to be close to the BOD target with a difference of 0.1 ~ 0.2 mg/L in all three watersheds during the mid-range flow interval (40 ~ 60%). In case of T-P, although the target water quality was not set, the water quality was improved by Cheonan A 46%, Kokgyo A 29% and Namwon A 25%. The Muhan and Sapgyo river basins meet the target grade of middle-watershed standards. The improvement effect will be positive, as water quality, which achieves the target of Total Load Management System and the target grade of the middle-watershed standards will be expected to flow into the Sapgyo lake.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.64-71
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• 2024

The external fuel tank of an aircraft is a main component that can increase the cruising range of the aircraft. It must be able to be stably separated from the pylon in an emergency situation. At this time, a separation load is applied to the fin and the pivot of the external fuel tank. To stably separate the external fuel tank, the structural soundness of the fin and the pivot must be confirmed. In this study, structural tests were conducted to verify the structural integrity of the external fuel tank pin and pivot when the external fuel tank was separated from the aircraft. Results are then presented. In this paper, a test configuration diagram consisting of the hydraulic and load control equipment, data acquisition system, and pneumatic supply unit used in the structural test was explained. Test installation and test load application plan for each test condition were provided. As results of the structural test, it was found that test load and internal pressure of the test specimen were properly controlled within the allowable range in each test. It was confirmed that serious structural defects in the test specimen did not occur under required load conditions. In conclusion, through structural test for design limit load and design ultimate load, it was proven that the fin and pivot of the external fuel tank for aircraft covered in this study had sufficient structural strength.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.245-251
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• 2008

The cooling load in winter is significant in buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. Hence, the development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the operating characteristics and performance of a simultaneous heating and cooling heat pump in the heating-main operating mode were investigated experimentally. The system adopted a variable speed compressor with four indoor units and one outdoor unit with R-410A. In the heating-main mode, the cooling capacity was lower than the design cooling capacity due to the reduction of the flow rate in the indoor unit for the cooling, with the increase of the heating capacity. To solve these problems, the performance characteristics of the simultaneous heating and cooling heat pump in the heating-main mode were investigated by varying the flow rate to the indoor unit for the cooling and the compressor rotating speed. In addition, the adequate control methods were suggested to improve the system efficiency.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.1-7
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• 1998

Due to the increase in capacity of auxiliary machinery in power plant, the importance of energy saving has been greatly emphasized. If the speed of fans or pumps is controlled in accordance with the variation of load, large electric energy can be saved. Large capacity inverter, 2MVA GTO inverter, has been developed by operating two of 1MVA unit inverters in parallel. The parallel operation of the unit inverter is accomplished through two output transformers of which the secondary windings are connected in series. The system is composed of one control cubicle, one rectifier cubicle and 2 unit inverter cubicles. This inverter system was applied to the sea water lift pump(SLP) driven by a 6.6KV 1500KW induction motor in Seo-Inchon power plant to save the electric energy. The parallel operation of inverters by 180 degrees apart in switching frequency helps to reduce the harmonic components.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.104-109
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• 2022

The bomb rack unit (BRU) installed inside the pylon serves to fix external attachments such as external fuel tank or external weapon, and also serves to separate external attachments in case of emergency. In particular, the load generated when the external attachment is separated from the BRU is called the punching load. In this study, we present the results of a structural static test performed to verify the structural integrity of the pylon under the BRU punching condition acting on it. In the structural static test report, we present the implementation method for the separation load of the external attachment and the test profile for the BRU punching load condition, and compared the error between the load input signal and the feed-back signal to determine the appropriateness of load control in each test. Furthermore, we compared the strain results obtained in the numerical analysis and structural test at the main positions of the specimen. As a result, it was shown that the load of the actuators were properly controlled within the allowable error range in each test, and the numerical analysis effectively predicted the test result. Finally, through structural static tests conducted by design limit load and design ultimate load, we verified that the aircraft pylon dealt with in this study has sufficient structural strength for external attachment separation condition.