• 대한기계학회논문집A
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• 제40권6호
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• pp.603-611
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• 2016

광물시장 성장과 함께, 고효율 DTH 해머 필요성이 함께 증가되고 있다. 그러나 DTH 해머는 지하 천공이라는 작동조건의 특성 때문에, 실험 데이터의 직접 취득이 어렵고, 실제 테스트를 하기 위해서는 DTH 드릴 리그와 많은 운용비를 필요로 한다. 본 연구에서는 이러한 DTH 해머의 제품개발 시간과 비용의 문제점을 컴퓨터 시뮬레이션을 이용하여 해결하고자 하였다. 이전 연구에서DTH 해머구조와 동작 원리를 분석하고, 시뮬레이션을 이용한 표준 모델을 제시하고, 그것을 실험과 비교 검증하였다. 이를 바탕으로 본 논문에서는 실험설계법을 이용하여DTH 해머의 타격에너지와 효율에 관한 제어인자를 도출하고, 이에 관한 최적화를 시도하였다. 그 결과 타격에너지를 14.9% 효율은 3.3% 높이는 결과를 얻었다.

• Journal of Biosystems Engineering
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• 제28권4호
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• pp.305-314
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• 2003

The ROPS of an agricultural tractor is designed to protect its driver when the tractor overturns. Although the current OECD tests to determine whether the ROPS meets the requirements of the OECD regulation are desirable, they need long time to test. We experimental time and effort by using CAE. We conducted a finite element analysis for the ROPS design of a Dae-Dong tractor cabin in an attempt to reduce the design and manufacturing time. This study shows the interpretative skill using MARC(v.2000) for designing ROPS and difference between the results of testing and FEA. Design process is generally divided into two phases: a concept and a detail design. The concept design uses simple analysis to predict structural behavior, whereas the detail design involves a finite element analysis performed by the results of the concept design. This study focused on the detail design and used Patran(v.2000r2) and MARC(v.2000) of the MSC software corporation. The model consisted of 4812 elements and 4582 nodes. Four tests. specified in the OECD standards, were performed: (1) longitudinal loading test (2) rear crushing test (3) side loading test (4), and front crushing test. Independent analyses were also performed for each test, along with a sequential analysis. When compared, the results of the independent and sequential analyses were found to be similar to the test results.

• 보건행정학회지
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• 제24권3호
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• pp.283-290
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• 2014

Background: This study aimed to examine the relationship between home-visit nursing services and health care utilization under the public long-term care insurance program in Korea. Methods: We analyzed the long-term care need assessment database and the long-term care and the health insurance claim databases of National Health Insurance Service between July 2011 and June 2012. The sample includes a total of 20,065 home-visit nursing recommended-older beneficiaries who use home-visit nursing and/or home-visit care, based on a standard benefit model developed by the Health Insurance Policy Institute of National Health Insurance Service. The beneficiaries were categorized into home-visit nursing use and non-use groups, and the home-visit nursing use group was again divided into high-use and low-use groups home-visit nursing, based on their total annual home-visit nursing expenditure. Two-part models and negative-binomial regression models were used for the statistical analysis. Results: The home-visit nursing use was negatively associated with the number of outpatient visit and cost, while adjusting for all covariates. The home-visit nursing use was also negatively associated with the inpatient cost among the high home-visit nursing use group. Conclusion: The findings implies home-visit nursing use prevents health care utilization. Further studies and policy strategies that can promote and strengthen home-visit nursing services under the public long-term care insurance are necessary in Korea.

• 대한안전경영과학회지
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• 제15권1호
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• pp.1-10
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• 2013

The recent trend in the war fields on the globe may be characterized by the network-centric warfare, which would, in turn, make the concept of weapon systems be changed. To this end, the concept of system of systems (SoS) has been introduced in literature. An SoS is a collection of multiple systems, each of which is an independent system and can be interoperable with each other. Thus, in defense domain each SoS is a big weapon system as a whole operated in actual environment and each element of it is also an independent smaller weapon system, but they should be interoperable via network among each other. The safety results studied for each elementary system alone may not be fully applicable to the whole SoS. As such, the objective of this paper is to study how to make the SoS safety requirements be distributed down over the interoperable elementary systems. Since handling the interoperability requires a technique of systems architecture, a standard method called the DoD Architectural Framework (DoDAF) has been used here to derive a solution. Using DoDAF, the safety requirements were first analyzed in the operability environment. The results were then studied to be included in an integrated model of both the systems design and safety processes. A further study of present paper would facilitate ensuring safety in the development of SoS weapon systems in practice.

• Nuclear Engineering and Technology
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• 제41권7호
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• pp.945-952
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• 2009

The Three Mile Island Unit 2 (TMI-2) accident provides unique full scale data, thus providing opportunities to check the capability of codes to model overall plant behavior and to perform a spectrum of sensitivity and uncertainty calculations. As part of the TMI-2 analysis benchmark exercise sponsored by the Organization for Economic Cooperation and Development Nuclear Energy Agency (OECD NEA), several member countries are continuing to improve their system analysis codes using the TMI-2 data. The Republic of Korea joined this benchmark exercise in November 2005. Seoul National University has analyzed the TMI-2 accident as well as the currently proposed alternative scenario along with a sensitivity study using the Modular Accident Analysis Program Version 4.03 (MAAP4.03) code in collaboration with the Korea Hydro and Nuclear Power Company. Two input files are required to simulate the TMI-2 accident with MAAP4: the parameter file and an input deck. The user inputs various parameters, such as volumes or masses, for each component. The parameter file contains the information on TMI-2 relevant to the plant geometry, system performance, controls, and initial conditions used to perform these benchmark calculations. The input deck defines the operator actions and boundary conditions during the course of the accident. The TMI-2 accident analysis provided good estimates of the accident output data compared with the OECD TMI-2 standard reference. The alternative scenario has proposed the initial event as a loss of main feed water and a small break on the hot leg. Analysis is in progress along with a sensitivity study concerning the break size and elevation.

• Journal of Information Processing Systems
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• 제15권6호
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• pp.1277-1295
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• 2019

With its technical development, digital printing is being universally introduced to the mass production of clothing factories. At the same time, many fashion platforms have been made for customers' participation using digital printing, and a tool is provided in platforms for customers to make designs. However, there is no sufficient solution in the production stage for automatically converting a customer's design into a file before printing other than designating a square area for the pattern designed by the customer. That is, if 30 different designs come in from customers for one shirt, designers have to do the work of reproducing the design on the clothing pattern in the same location and in the same angle, and this work requires a great deal of manpower. Therefore, it is necessary to develop a technology which can let the customer make the design and, at the same time, reflect it in the clothing pattern. This is defined in relation to the existing clothing pattern with digital printing. This study yields a clothing pattern for digital printing which reflects a customer's design in real time by matching the diagram area where a customer designs on a given clothing model and the area where a standard pattern reflects the customer's actual design information. Designers can substitute the complex mapping operation of programmers with a simple area-matching operation. As there is no limit to clothing designs, the variousfashion design creations of designers and the diverse customizing demands of customers can be satisfied at low cost with high efficiency. This is not restricted to T-shirts or eco-bags but can be applied to all woven wear, including men's, women's, and children's clothing, except knitwear.

• 한국전자거래학회지
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• 제12권2호
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• pp.47-74
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• 2007

전자상거래 인적자원의 양성과 개발을 위해서 자격은 학위와 더불어 지식축적의 결과를 표시하는 대표적인 지표이다. 하지만 기존의 출제기준은 전자상거래 시장변화를 포함한 현장성 반영과 업무에의 활용도가 부족하여 개선이 요구된다. 본 연구는 전자상거래관리사 직무분석을 통하여 산업현장에서 요구되는 능력을 체계적으로 분석하여 출제기준을 개선하고자 하였다. 연구목적의 달성을 위해 국내외 전자상거래 관련 자격현황 조사 및 문헌연구를 수행하고 직무분석을 통하여 전자상거래관리사 직무의 구조와 과업을 도출함으로써 기존의 과업목록을 보강하였으며, 과업분석을 통하여 각 과업별로 요구되는 필요지식, 기술 등의 능력요소들을 도출하였다. 도출된 직무의 범위와 과업목록을 검증하고 이를 바탕으로 기존의 출제기준과 비교분석하여 개선방안을 제시하였다. 연구방법으로는 전자상거래 자격관련 문헌과 현황을 조사하였으며, 직무분석단계에 전문가 면담조사와 전문가위원회 조사가 수행되었으며 검증단계에 설문조사와 면담조사를 수행한 후 전문가위원회를 통해 출제기준 개선방안을 설계하고 확인하였다.

• Journal of Radiation Protection and Research
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• 제41권4호
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• pp.368-372
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• 2016

Background: Methodologies for a series of radiological consequence assessments show a distinctive difference according to the design principles of the original nuclear suppliers and their technical standards to be imposed. This is due to the uncertainties of the accidental source term, radionuclide behavior in the environment, and subsequent radiological dose. Both types of PWR and PHWR are operated in Korea. However, technical standards for evaluating atmospheric dispersion have been enacted based on the U.S. NRC's positions regardless of the reactor types. For this reason, it might cause a controversy between the licensor and licensee of a nuclear power plant. Materials and Methods: It was modelled under the framework of the NRC Regulatory Guide 1.145 for light-water reactors, reflecting the features of heavy-water reactors as specified in the Canadian National Standard and the modelling features in MACCS2, such as atmospheric diffusion coefficient, ground deposition, surface roughness, radioactive plume depletion, and exposure from ground deposition. Results and Discussion: An integrated accident consequence assessment code, ACCESS (Accident Consequence Assessment Code for Evaluating Site Suitability), was developed by taking into account the unique regulatory positions for reactor types under the framework of the current Korean technical standards. Field tracer experiments and hand calculations have been carried out for validation and verification of the models. Conclusion: The modelling approaches of ACCESS and its features are introduced, and its applicative results for a hypothetical accidental scenario are comprehensively discussed. In an applicative study, the predicted results by the light-water reactor assessment model were higher than those by other models in terms of total doses.

• Coupled systems mechanics
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• 제9권2호
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• pp.163-182
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• 2020

Coupled thermo-mechanical analysis of reinforced concrete slab at elevated temperatures from a fire accounting for nonlinear thermal parameters is carried out. The main focus of the paper is put on a one-way continuous reinforced concrete slab exposed to fire from the single (bottom) side as the most typical working condition under fire loading. Although contemporary techniques alongside the fire protection measures are in constant development, in most cases it is not possible to avoid the material deterioration particularly nearby the exposed surface from a fire. Thereby the structural fire resistance of reinforced concrete slabs is mostly influenced by a relative distance between reinforcement and the exposed surface. A parametric study with variable concrete cover ranging from 15 mm to 35 mm is performed. As the first part of a one-way coupled thermo-mechanical analysis, transient nonlinear heat transfer analysis is performed by applying the net heat flux on the exposed surface. The solution of proposed heat analysis is obtained at certain time steps of interest by α-method using the explicit Euler time-integration scheme. Spatial discretization is done by the finite element method using a 1D 2-noded truss element with the temperature nodal values as unknowns. The obtained results in terms of temperature field inside the element are compared with available numerical and experimental results. A high level of agreement can be observed, implying the proposed model capable of describing the temperature field during a fire. Accompanying thermal analysis, mechanical analysis is performed in two ways. Firstly, using the guidelines given in Eurocode 2 - Part 1-2 resulting in the fire resistance rating for the aforementioned concrete cover values. The second way is a fully numerical coupled analysis carried out in general-purpose finite element software DIANA FEA. Both approaches indicate structural fire behavior similar to those observed in large-scale fire tests.

• 한국산학기술학회논문지
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• 제7권1호
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• pp.12-20
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• 2006

국가차원의 신 재생에너지 활성화 방안에 따라 풍력발전 등의 대규모 분산전원 단지의 도입이 이루어지고 있으나, 이에 대한 기술적인 평가방안이나 해석 방법이 구체적으로 제시되어 있지 않아, 설치자(시도 및 지자체)와 운용자(한전의 배전지사/지점)들은 많은 혼돈과 어려움을 겪고 있는 실정이다. 따라서 본 논문에서는 태양광, 풍력 등의 분산전원이 배전계통에 도입되는 경우, 계통 연계에 대한 기술적인 적합여부를 종합적으로 평가하는 시스템을 개발하였다. 즉, 분산전원을 제작하거나 시공하는 업체와 일반 운용자나 사용자(분산전원을 잘 모르는 비전문가 포함)들이 손쉽게 접근하여, 분산전원의 연계시의 기술적인 문제점과 적합 여부를 판단하는 기술지원 평가 S/W를 제작하였다. 주요 평가 기능으로서는 분산전원의 계통연계 시에 발생할 수 있는 정상, 비정상(사고), 전력품질에 대한 항목으로서, 누구나 동일한 결과를 얻을 수 있는 표준계통에 근거한 평가 알고리즘에 의하여 연계 적합 여부를 판단하는 것이다.