• 한국융합학회논문지
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• 제9권3호
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• pp.223-230
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• 2018

본 연구는 국방연구개발사업의 자료를 통하여 사업 수행 간 원가가 변동되는 양상을 분석하였다. 2가지 형태의 모형을 활용한 실증분석을 통하여 원가변동(개산원가 대비 정산원가)에 영향을 미치는 원가비목과 그 영향력을 확인하였다. 모형1(17개 원가 비목)을 활용한 검증 결과, 17개 원가 비목 중 감가상각비, 관세 등 4개 원가 비목을 제외하고 정산원가 차액과 상관관계를 가지는 것을 확인하였다. 대표적으로 직접노무비의 영향력은 1.022이고 외주가공비의 영향력은 0.942로 확인되었다. "직접노무비 중심의 원가 계산"을 고려한 모형2(직접비)를 이용한 검증 결과, 모든 직접 원가 비목이 정산원가 차액과 상관관계를 가지는 것을 확인하였다. 대표적으로 직접노무비의 영향력은 2.014이고 외주가공비의 영향력은 1.068로 확인되었다. 이 연구의 결과를 통해 "직접노무비 중심의 원가계산"을 실증분석 하였고, 외주가공비를 활용한 원가 절감 유인 또한 발견하였다.

• 대한수학회논문집
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• 제11권2호
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• pp.285-294
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• 1996

In this paper, we show relations between injective covers and direct sums, some commutative properties, and composition properties in the injective covers.

• 통상정보연구
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• 제16권3호
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• pp.183-202
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• 2014

2007년부터 2012년까지의 외국인직접투자 유치액에 대한 산업별 투자유치 인센티브인 재정지원액을 중심으로 정책집행에 따른 정책의 시차효과를 분석하였다. 분석결과 우리나라의 외국인직접투자유치정책의 시차효과는 정책집행 후 2~3년 정도의 시차가 발생하는 것으로 분석되었다. 따라서 우리나라의 외국인직접투자 유치정책의 방향은 조세감면제도 보다는 직접보조금 혹은 재정지원(금융)과 같은 현실적인 정책수단을 강화해야 할 것이다.

• 한국통신학회논문지
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• 제31권12C호
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• pp.1265-1272
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• 2006

본 논문에서는 OFDM을 기반으로 하는 직접변환(Direct-conversion) 수신기에서 발생하는 I/Q 불균형(mismatch)문제를 효과적으로 제거할 수 있는 새로운 보상기법을 제시한다. OFDM심볼에 0의 값을 갖는 null 부반송파를 삽입하여 전송한 후에, 수신단에서 FFT후의 null 부반송파로부터 I/Q 불균형 관한 파라미터 값을 추정하고, 이를 이용하여 데이터 심볼에서 I/Q 불균형 효과를 제거하는 방법으로, 효율적이며 낮은 복잡성(complexity)이 제안 방식의 수요 특징이다. 모의실험 결과로부터 소수의 null 부반송파로도 충분한 I/Q 불균형 효과를 제거하는 결과를 얻을 수 있었다. 또한 제안된 방식은 주파수 선택적 페이딩 채널에서도 I/Q 불균형이 잘 제거됨을 보였다.

• Ocean Systems Engineering
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• 제4권1호
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• pp.63-82
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• 2014

Declutching control is applied to a hemispherical wave energy converter with direct linear electric Power-Take-Off systems oscillating in heave direction in both regular and irregular waves. The direct linear Power-Take-Off system can be simplified as a mechanical spring and damper system. Time domain model is applied to dynamics of the hemispherical wave energy converter in both regular and irregular waves. And state space model is used to replace the convolution term in time domain equation of the heave oscillation of the converter due to its inconvenience in analyzing the controlled motion of the converters. The declutching control strategy is conducted by optimal command theory based on Pontryagin's maximum principle to gain the controlled optimum sequence of Power-Take-Off forces. The results show that the wave energy converter with declutching control captures more energy than that without control and the former's amplitude and velocity is relatively larger. However, the amplification ratio of the absorbed power by declutching control is only slightly larger than 1. This may indicate that declutching control method may be inapplicable for oscillating wave energy converters with direct linear Power-Take-Off systems in real random sea state, considering the error of prediction of the wave excitation force.

• Journal of Power Electronics
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• 제17권5호
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• pp.1211-1222
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• 2017

In order to decrease the parameter sensitivity of deadbeat direct torque control (DB-DTC), an improved deadbeat direct torque control method for surface mounted permanent-magnet synchronous motor (SPMSM) drives is proposed. First, the track errors of the stator flux and torque that are caused by model parameter mismatch are analyzed. Then a sliding mode observer is designed, which is able to predict the d-q axis currents of the next control period for one-step delay compensation, and to simultaneously estimate the model parameter disturbance. The estimated disturbance of this observer is used to estimate the stator resistance offline. Then the estimated resistance is required to update the designed sliding-mode observer, which can be used to estimate the inductance and permanent-magnetic flux linkage online. In addition, the flux and torque estimation of the next control period, which is unaffected by the model parameter disturbance, is achieved by using predictive d-q axis currents and estimated parameters. Hence, a low parameter sensitivity DB-DTC method is developed. Simulation and experimental results show the validity of the proposed direct control method.

• 설비공학논문집
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• 제3권3호
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• pp.153-160
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• 1991

Heat transfer characteristics of a direct contact heat exchanger utilizing sieve trays and spray nozzles for steam condensation for the purpose of combining with a LNG evaporator have been investigated with various cooling water flow rates and different vacuum pressures within the heat exchanger for the purpose of steam condensation. Temperature profiles and the volumetric overall heat transfer coefficients in a direct contact heat exchanger have been obtained for comparisons. The results show that the temperature differences between cooling water and steam along the direct contact heat exchanger height are rapidly decreasing and the volumetric overall heat transfer coefficients of the exchanger improves greatly as the inside vacuum pressure increases. The values of the overall heat transfer coefficients at P=-680mmHg have been increased significantly compared with at atmospheric pressure. At given pressure conditions, it is found that the values of average volumetric overall heat transfer coefficients for the sieve tray are found to be approximately 10% higher than those of the spray nozzle.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.555-562
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• 2021

This study aims to understand the effect of millennial transformational leadership (MTL) on organizational performance in Indonesian Fishery startups. The population of this study included select fishery startups in Indonesia based on the data released by the Ministry of Marine Affairs and Fisheries of the Republic of Indonesia and Digital Fishery Network. This study used the statistical method of PLS-SEM to analyze the data. The findings show that the MTL has no direct positive relationship with organizational performance; MTL has a direct positive relationship with organizational agility; MTL has a direct positive relationship with IT capability; IT capability has a direct positive relationship with organizational agility; organizational agility has a direct positive relationship with organizational performance in fishery startups in Indonesia during this pandemic era. It is suggested that future researches use covariance-based-structural equation modeling which is able to test the research model's feasibility. Roles of mediating variables in addition to the main variables-for example, organizational agility as a mediating variable on the relationship between MTL and organizational performance - are also suggested to be examined. In spite of the limitations, the model developed is still interesting to investigate and is expected to enhance the literature on transformational leadership.

• 산경연구논집
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• 제12권9호
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• pp.31-42
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• 2021

Purpose: After the reform and opening up, China's overall economic development has entered a new era. From mutual investment and trade transactions between domestic provinces and regions to investment and trade with foreign companies, the continuous supplement of investment funds makes the follow-up development of all aspects of economic development smoother and has played a strong impetus. effect. Foreign direct investment has many influences on the economic development of a country or region. Research design, data and methodology: This article uses the sample data of Shandong Province from 2011 to 2019 to analyze the foreign direct investment in Shandong Province by industry, region, method and other aspects, and study the relationship and influence between foreign direct investment and economic growth. Results: The results show that there is a relatively close relationship between foreign direct investment and economic growth, and it has played a role in promoting economic development in many aspects such as industrial structure, foreign trade, and employment. Conclusions: At the same time, corresponding suggestions are put forward based on the analysis and conclusions drawn.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.19-29
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• 2022

The 2D/1D method has become the mainstream of the direct transport calculation considering the balance of accuracy and efficiency. However, the 2D/1D method still suffers from stability issues. Recently, a quasi-3D method has been proposed with axial Legendre expansion. Analysis and comparison of the 2D/1D and quasi-3D method is conducted in theory from the equation derivation. Besides, the C5G7 benchmark, the KUCA benchmark and the macro BEAVRS benchmark are calculated to verify the theory comparisons of these two methods with the direct transport code SHARK. All results show that the quasi-3D method has better stability and accuracy than the 2D/1D method with worse efficiency and memory cost. It provides a new option for direct transport calculation with the quasi-3D method.