• 한국지반공학회논문집
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• 제18권4호
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• pp.21-32
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• 2002

말뚝 선단 조건에 따른 충격반향기법의 시간영역 신호를 실내 모형실험에 의하여 분석하였다. 선단조건으로는 자유단, 고정단, 암반 근입, 연약 선단부의 네 가지 조건을 고려하였으며, 이를 위하여 폴리우레탄 재질의 모형말뚝과 모노캐스트 재질의 모형암반을 제작하여 실험을 수행하였다. 실내실험 결과 각각의 경계조건에 대한 신호의 특성을 파악할 수 있었으며, 말뚝 선단 조건뿐만 아니라 말뚝과 주변 암반과의 부착상태도 추정할 수 있는 가능성을 확인하였다. 또한 실내 모형실험의 결과를 검증하기 위하여 현장실험을 수행하였으며, 암반 근입 말뚝에 대한 신호 분석 결과 충격반향기법에 의한 현장타설말뚝의 비파괴 건전도 평가는 적용성이 충분히 있는 것으로 파악되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2499-2522
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• 2017

Multi-hop networks are a low-setup-cost solution for enlarging an area of network coverage through multi-hop routing. Carrier sense multiple access with collision avoidance (CSMA/CA) is frequently used in multi-hop networks. Multi-hop networks face multiple problems, such as a rise in contention for the medium, and packet loss under heavy-load, saturated conditions, which consumes more bandwidth due to re-transmissions. The number of re-transmissions carried out in a multi-hop network plays a major role in the achievable quality of service (QoS). This paper presents a statistical, analytical model for the end-to-end delay of contention-based medium access control (MAC) strategies. These strategies schedule a packet before performing the back-off contention for both differentiated heterogeneous data and homogeneous data under saturation conditions. The analytical model is an application of Markov chain theory and queuing theory. The M/M/1 model is used to derive access queue waiting times, and an absorbing Markov chain is used to determine the expected number of re-transmissions in a multi-hop scenario. This is then used to calculate the expected end-to-end delay. The prediction by the proposed model is compared to the simulation results, and shows close correlation for the different test cases with different arrival rates.

• 대한기계학회논문집
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• 제13권3호
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• pp.433-442
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• 1989

본 연구에서는 볼 엔드 밀 절삭실험을 통하지 않고 일반적인 선삭가공 등에서 쉽게 구할 수 있는 2차원 절삭 데이터를 이용하여 볼 엔드 밀의 기하학적 형상 및 절삭조건이 주어졌을 때 모든 볼 엔드 밀 가공에서의 절삭기구를 해석하고 절삭력 모델을 구하고자 한다. 이를 위하여 볼 엔드 밀의 기하학적 특성 및 절삭 조건 등을 분석하고, 미소절삭날터를 이용한 3차원 절삭해석방법을 적용하여 미소 절삭력을 구하고 이들의 합력으로서 절삭력을 계산한다.

• 대한건축학회논문집:구조계
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• 제36권4호
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• pp.123-133
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• 2020

The purpose of this study is to analyze the method of retrofitting flexural strength and the flexural performance of retrofitted shear walls. There are various ways to reinforce the flexural strength of reinforced concrete shear wall structural systems that have already been built, in the case of that, the external force is increased, and the internal force is insufficient. However, there are various problems, such as excessive flexural stiffness after reinforcement and increasing the thickness and length of the wall. We have developed a retrofit method to solve these problems. The wall end is excavated to place the required vertical rebars, and concrete is poured after placing rebars. This is the same concept as creating wall end boundary elements later on. We also studied the anchorage method of reinforcement and the interaction method between the retrofitting end and the existing wall. The flexural test results for the reinforced concrete shear wall using the studied retrofit method can be predicted according to the sectional analysis and FEM analysis, and there are differences in the plastic hinge length, crack propagation, stiffness degradation and energy dissipation due to the bending depending on the vertical rebar ratio of wall end.

• The Journal of Asian Finance, Economics and Business
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• 제8권1호
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• pp.443-450
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• 2021

The paper investigates the factors that affect the decision of young Chinese consumers to buy high-end cosmetics. The study is based on the responses obtained by questionnaires from 400 respondents in Guangzhou, China. The information was collected and classified on the basis of gender, occupation, age and education in order to understand the main characteristics of the sample in a better way. The purposive, convenient and quota sampling techniques of non-probability sampling method were used. Besides this, the predictive test was carried out with 30 respondents to ensure the reliability and validity of the questionnaires. The data was put to descriptive statistical analysis and multiple regression analysis in order to verify the hypotheses. The data revealed that, while brand awareness does not affect the consumer attitude about the high-end cosmetics, other factors like product involvement, perceived quality, subjective norm, and word-of-mouth have significant effect on consumer's attitude and consumers' intention about high-end cosmetics. The findings of the study show that subjective norm, perceived value, word-of-mouth, and consumer attitude of cosmetic products highly affect consumers purchase intention of high-end cosmetic products. The research paper helps to form concrete and effective marketing strategy based on various aspects of consumer behavior for high-end cosmetics in China.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.603-610
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• 2005

The end bearing behavior of piles socketed in weathered/soft rock is generally dependent upon the mass conditions of rock with fractures rather than the strength of intact rock. However, there are few available data and little guidance in the prediction of the end bearing capacity of drilled shafts socketed in weathered/soft rock, considering rock mass weathering. Therefore, a database of 13 load tests was constructed first, and new empirical relationships between the base reaction modulus of piles in rock and rock mass properties were developed. No correlation was found between the compressive strengths of intact rock and the base reaction modulus of weathered/soft rock. The ground investigation data regarding the rock mass conditions(e.g. Em, Eur, RMR, RQD) was found to be highly correlated with the base reaction modulus, showing the coefficients of correlation greather than 0.7 in most cases. Additionally, the applicability of existing methods for the end bearing capacity of piles in rock was verified by comparison with the field test data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2019_2020
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• 2009

A recurrent surge oscillograph(RSO) test was performed at the Taean thermal power plant on #5 turbine generator. The test was conducted using a rotor reflectometer and digital oscilloscope. A DC voltage step is applied to each end of the rotor winding in turn. Each reflected wave, at the input end of the winding, is monitored and the two waveforms are superimposed automatically and monitored on a single channel oscilloscope. As the half windings in a rotor are identical, the two waveforms monitored at each end of the rotor will also be identical for a healthy winding. A winding with a fault will cause different voltages to be monitored at the two ends.

• 한국기계가공학회지
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• 제17권3호
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• pp.109-119
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• 2018

The purpose of this study is to evaluate the structural safety of the front-end loader for the 90 kW class of agricultural tractors in impact test conditions. Deformation and stress on the loader under the impact test conditions are analyzed using the commercial finite element analysis software ANSYS. In previous research dealing with the initial design of the loader, the maximum stress occurred in the mount and exceeded the yield strength of the material. In this paper, an improved design of the mount of the loader was proposed to reduce the stress concentration in the initial design. The safety of the improved design was verified by performing rigid-body dynamics analysis, transient structural analysis, and static structural analysis under three impact test conditions: a drop and catch test, a corner pull test, a corner push test. It was found that the local stress concentration in the mount that appeared in the initial design was greatly reduced in the improved design, and that the maximum stresses occurred in the three impact test conditions are smaller than the yield strength. It is expected that the design improvement of the mount proposed in this study and the method of analysis may be effectively used to enhance structural safety in the development of new model front loaders in the future.

• 한국콘텐츠학회논문지
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• 제22권8호
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• pp.628-639
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• 2022

본 연구는 환자와 환자 가족에게 최상의 임종간호를 제공하기 위해 간호사가 인식하는 최상의 임종간호와 웰다잉 간의 관계를 조사하였다. 연구대상은 서울 소재 종합병원에 근무하는 간호사 121명을 대상으로 2021년 4월 28일부터 5월 12일까지 수집된 자료를 분석하였다. SPSS/WIN 27.0을 이용하여 t-test, ANOVA, Pearson correlation coefficients로 분석하였다. 본 연구의 결과 대상자의 최상의 임종간호에 대한 인식의 총 평균은 5점 척도상 4.04±0.82점으로 최상의 임종간호에 전반적으로 '동의한다' 수준을 나타냈다. 웰다잉에 대한 인식의 총 평균은 5점 척도상 3.63±1.14점으로 평화롭게 죽는 것을 가장 중요하게 인식하였다. 대상자의 일반적 특성 중 연령에 따른 최상의 임종간호에 유의한 차이를 나타내(t=-.97, p=.013) 30대 간호사군이 20대 간호사군에 비해 최상의 임종간호에 더 높은 동의수준을 나타냈다. 최상의 임종간호와 웰다잉의 상관관계를 분석한 결과 유의한 상관관계는 없는 것으로 나타났다. 본 연구의 결과는 경력이 낮은 젊은 간호사들의 임종간호 인식을 높이기 위한 교육이 제공되어야 함을 시사한다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.33-33
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• 2009

This study is to develop the resistance welding apparatus and investigate the welding characteristics of Zircaloy-4 end-plate of fuel bundle in the cases of the resistance welding and the laser beam welding. The welding parameters which affect the weld nugget and the torque values have been also compared. The effect of the torque strength of end-plate welding using by the resistance welding and the laser beam welding has been studied and optimum conditions of Zircaloy-4 end-plate welding have been found. Futhermore, micro-structures and micro-hardness of the resistance welded specimens have been also compared.