• 한국추진공학회지
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• 제15권4호
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• pp.85-93
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• 2011

아크 채널 모델을 이용하여 플라즈마 온도를 매개로 플라즈마 입력전력과 전류 조건에 따른 간극 반지름(R) 및 간극팩 묶음 길이(L) 변수 계산이 가능한 해석해를 유도하고 이를 이용하여 300 A 전류조건에서 0.4 MW 급 분절형 아크 플라즈마 토치에 대한 해석적 설계 변수 해석을 수행하였다. 해석 결과, R��${\leq}$ 7.5 mm, L ${\leq}$ 1.25 m 인 범위에 대해, L이 길어지거나 R이 작아질 때, 플라즈마 온도는 비례하여 증가하는 경향을 가지고 있음을 알 수 있었으며, 그 이상의 범위에서는 증가하다 감소하는 비선형 현상이 존재하여 주어진 전류 및 전력조건에서 아크 플라즈마의 형성이 불가능하거나 불안정할 것으로 예측되었다. 이와 같은 결과를 바탕으로 입력전류가 300 A 일 때, 아크 플라즈마 온도를 안정적으로 구현할 수 있을 것이라 여겨지는 0.4 MW 급 분절형 아크 플라즈마 토치의 간극 반지름 R 및 간극팩 묶음 길이 L의 설계범위를 각각 5.5 mm ${\leq}$ R ${\leq}$ 7.5 mm, 0.25 m ${\leq}$ L ${\leq}$ 0.5 m 범위로 제안하였다.

• 융합정보논문지
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• 제10권2호
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• pp.167-175
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• 2020

본 연구는 병원종사자들의 이직의도 결정시 가장 큰 원인이 될 수 있는 관계갈등 종류를 살펴보고, 이직의도를 완화시킬 수 있는 관계갈등 요인과 스트레스 요인을 파악하여 병원조직의 안정적인 인력관리를 위한 유용한 정보제공을 목적으로 실시하였다. 연구방법은 병원 및 종합병원에 근무하고 있는 행정직과 간호직 종사자들을 대상으로 2019년 9월 16일부터 9월 30일까지 구조화된 설문자료를 수집하여, t-test, 분산분석, 카이제곱 검정, 회귀분석을 실시하였다. 분석결과, 이직결정시 가장 큰 원인이 될 수 있는 갈등종류는 병원에서 얻을 것이 없는 경우에 이직할 것이라는 응답이 과반수이상이었다. 행정직은 상사나 선임자의 자기중심적 언행으로 인한 관계갈등이 높을수록 그리고 불명확한 업무지시로 인한 스트레스가 높을수록 현재 이직의향이 높았으며, 간호직은 상사나 선임자의 자기중심적 언행으로 인한 관계갈등이 높을수록 그리고 무시하는 행동 및 불쾌한 언행으로 인한 스트레스가 높을수록 현재 이직의향이 높은 것으로 확인되었다. 따라서 병원조직이 안정적인 인력관리를 위해서는 조직차원에서의 조직문화와 부서차원에서의 조직문화가 조직구성원들이 직무현장에서 실질적으로 체감할 수 있도록 검토할 필요성이 제기되었다.

• 전자공학회논문지T
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• 제35T권1호
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• pp.90-98
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• 1998

본 논문은 유도전동기를 저속에서 강건하게 제어할 수 있도록 개선된 벡터 제어에 관한 연구이다. 유도전동 기가 정격 속도의 10% 이하인 저속에서 구동될 경우 고조파에 의하여 발생하는 단위 벡터각 오차를 보상하는 알고리즘을 제안하였다. 또한 저속 및 과도상태에서 회전자 파라미터 변화에 대하여 강건하게 운전하도록 회전 자 시정수에 동조하는 알고리즘을 제시하였다. 제안한 벡터 제어를 이용하여 자속과 토오크 리플을 감소시킴으로써 저속에서 안정된 출력특성을 얻을 수 있었다. 입출력이 정현적인 상태일 때, 제안한 벡터 제어와 직접 벡터 제어 및 간접 벡터 제어의 저속 특성을 비교 분석하였고, 고조파가 함유된 상태에서 각각의 제어 특성을 비교 분석하였다. 그리고 회전자 시정수의 추종 성능은 시뮬레이션으로 확인하였다. 전체 제어 시스템을 실제의 하드웨어로 구현하고, 제안한 벡터 제어와 직접 벡터 제어를 비교 분석하였다. 두 제어 기법을 저속에서 실험 한 결과, 정상상태에서 직접 벡터를 기준으로 할 경우 토오크 리플이 45% 개선된 특성을 얻었다. 또한 자속 전류 리플은 0.2 p.u. 감소하였고, 토오크 전류 리플은 0.6 p.u. 감소함을 확인하였다. 그리고 회전자 시정수의 변화에 대하여 동조됨을 확인하였다. 따라서 저속에서 제안한 벡터 제어의 타당성과 강건성을 입증하였다.

• Journal of electromagnetic engineering and science
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• 제1권1호
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• pp.73-77
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• 2001

We studied the fabrication of GaAs-based pseudomorphic high electron mobility transistors(PHEMT`s) for the purpose of millimeter- wave applications. To fabricate the high performance GaAs-based PHEMT`s, we performed the simulation to analyze the designed epitaxial-structures. Each unit processes, such as 0.1 m$\mu$$\Gamma$-gate lithography, silicon nitride passivation and air-bridge process were developed to achieve high performance device characteristics. The DC characteristics of the PHEMT`s were measured at a 70 $\mu$m unit gate width of 2 gate fingers, and showed a good pinch-off property ($V_p$= -1.75 V) and a drain-source saturation current density ($I_{dss}$) of 450 mA/mm. Maximum extrinsic transconductance $(g_m)$ was 363.6 mS/mm at $V_{gs}$ = -0.7 V, $V_{ds}$ = 1.5 V, and $I_{ds}$ =0.5 $I_{dss}$. The RF measurements were performed in the frequency range of 1.0~50 GHz. For this measurement, the drain and gate voltage were 1.5 V and -0.7 V, respectively. At 50 GHz, 9.2 dB of maximum stable gain (MSG) and 3.2 dB of $S_{21}$ gain were obtained, respectively. A current gain cut-off frequency $(f_T)$ of 106 GHz and a maximum frequency of oscillation $(f_{max})$ of 160 GHz were achieved from the fabricated PHEMT\\`s of 0.1 m$\mu$ gate length.h.

• 가정과삶의질연구
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• 제32권4호
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• pp.75-89
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• 2014

The purpose of this study is to explore whether the phenomenon of both married and unmarried adults' cohabiting with their parents in Korean society is "unilaterally parasitic" on the child's side, or is "interdependent", characterized by expectation and dependence from the parent's side. As a result of this study possessing the characteristics of theoretic research, the following propensities of parent-dependent adults have been discussed. First of all, it was discovered that the ratio of adult children dependent on and cohabiting with their parents is considerable. Second, parents cohabiting with their adult children have unfavorable sociological features, such as high age, low level of education and income, and lower standards of education and income, compared to parents in normal households. Third, it was found that parent-dependent adults in Korean society maintain a relatively high rate of financial activity and stable employment-based occupation status. Fourth, it was shown that the level of satisfaction on the relationship between parent-dependent adults and their parents was discovered to be high, which is contrastive to the prediction of negative results based on some previous researches. Single adult children's age, their level of education and financial activity status, and their parents' age and level of education were deducted as variables related to the level of satisfaction of the relationship between parents and their children. It seems that the issue of married and unmarried adults' cohabiting with their parents in Korean society should be approached from various perspectives such as political, economic, socio-cultural and developmental aspects. On the basis of this fundamental awareness and several of the materials, it is pertinent that approaches to both married and unmarried adults' cohabiting with parents in Korean society should be distinguished from approaches to those in Japanese or Western society because it reflects the uniqueness of Korean society. In the phenomenon of married and unmarried adults' cohabiting with their parents in Korean society, there are several factors besides the economic factor, especially the socio-cultural factor that have the characteristics of mutual dependence between parents and their children rather than those of unilateral parasitism, in contrast with the phenomenon in Japanese or Western society. This research was aimed to contribute by establishing basic data for policy making by providing necessary information to treat the issues of instability and anxiety related to families and reflection on the matters of generations and parent-child relationships in current Korean society.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.477-477
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• 2008

For more than three decades, the gate dielectrics in CMOS devices are $SiO_2$ because of its blocking properties of current in insulated gate FET channels. As the dimensions of feature size have been scaled down (width and the thickness is reduced down to 50 urn and 2 urn or less), gate leakage current is increased and reliability of $SiO_2$ is reduced. Many metal oxides such as $TiO_2$, $Ta_2O_4$, $SrTiO_3$, $Al_2O_3$, $HfO_2$ and $ZrO_2$ have been challenged for memory devices. These materials posses relatively high dielectric constant, but $HfO_2$ and $Al_2O_3$ did not provide sufficient advantages over $SiO_2$ or $Si_3N_4$ because of reaction with Si substrate. Recently, $HfO_2$ have been attracted attention because Hf forms the most stable oxide with the highest heat of formation. In addition, Hf can reduce the native oxide layer by creating $HfO_2$. However, new gate oxide candidates must satisfy a standard CMOS process. In order to fabricate high density memories with small feature size, the plasma etch process should be developed by well understanding and optimizing plasma behaviors. Therefore, it is necessary that the etch behavior of $HfO_2$ and plasma parameters are systematically investigated as functions of process parameters including gas mixing ratio, rf power, pressure and temperature to determine the mechanism of plasma induced damage. However, there is few studies on the the etch mechanism and the surface reactions in $BCl_3$ based plasma to etch $HfO_2$ thin films. In this work, the samples of $HfO_2$ were prepared on Si wafer with using atomic layer deposition. In our previous work, the maximum etch rate of $BCl_3$/Ar were obtained 20% $BCl_3$/ 80% Ar. Over 20% $BCl_3$ addition, the etch rate of $HfO_2$ decreased. The etching rate of $HfO_2$ and selectivity of $HfO_2$ to Si were investigated with using in inductively coupled plasma etching system (ICP) and $BCl_3/Cl_2$/Ar plasma. The change of volume densities of radical and atoms were monitored with using optical emission spectroscopy analysis (OES). The variations of components of etched surfaces for $HfO_2$ was investigated with using x-ray photo electron spectroscopy (XPS). In order to investigate the accumulation of etch by products during etch process, the exposed surface of $HfO_2$ in $BCl_3/Cl_2$/Ar plasma was compared with surface of as-doped $HfO_2$ and all the surfaces of samples were examined with field emission scanning electron microscopy and atomic force microscope (AFM).

• E2M - 전기 전자와 첨단 소재
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• 제7권4호
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• pp.317-324
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• 1994

In this study, new preparation method of LiCoO$_{2}$ was applied to develop cathode active material for Li rechargeable cell, and followed by X-ray diffraction analysis, electrochemical properties and initial charge/discharge characteristics as function of current density. HC8A72- and CC9A24-LiCoO$_{2}$ were prepared by heating treatment of the mixture of LiOH H$_{2}$O/CoCO$_{3}$(1:1 mole ratio) and the mixture of Li$_{2}$CO$_{3}$/CoCO$_{3}$(1:2 mole ratio) at 850 and 900.deg. C, respectively. Two prepared LiCoO$_{2}$s were identified as same structure by X-ray diffraction analysis. a and c lattice constant were 2.816.angs. and 14.046.angs., respectively. The electrochemical potential of CFM-LiCoO$_{2}$(Cyprus Foote Mineral Co.'s product), HC8A72-LiCoO$_{2}$ and CC9A24 LiCoO$_{2}$ electrode were approximately between 3.32V and 3.42V vs. Li/Li reference electrode. Stable cycling behavior was obtained during the cyclic voltammetry of LiCoO$_{2}$ electrode. According as scan rate increases, cathodic capacity decreases, but redox coulombic efficiency was about 100% at potential range between 3.6V and 4.2V vs. Li/Li reference electrode. Cathodic capacity of HC8A72-LiCoO$_{2}$ was 32% higher than that of CFM-LiCoO$_{2}$ and that of CC9A24-LiCoO$_{2}$ was 47% lower than that of CFM-LiCoO$_{2}$ at 130th cycle in the condition of lmV/sec scan rate. Constant cur-rent charge/discharge characteristics of LiCoO$_{2}$/Li cell showed increasing Ah efficiency with initial charge/discharge cycle. Specific discharge capacities of CFM and HC8A72-LiCoO$_{2}$ cathode active materials were about 93mAh/g correspondent to 34% of theretical value, 110mAh/g correspondent to 40% of theretical value, respectively. In the view of reversibility, HC8A72-LiCoO$_{2}$ was also more excellent than CFM- and CC9A24-LiCoO$_{2}$.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.768-774
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• 2010

아크 채널 모델을 이용하여 플라즈마 온도를 매개로 플라즈마 입력전력과 전류 조건에 따른 간극 반지름(L) 및 간극팩 묶음 길이(R) 변수 계산이 가능한 해석해를 유도하고 이를 이용하여 300 A 전류조건에서 0.4 MW 급 분절형 아크 플라즈마 토치에 대한 해석적 설계 변수 해석을 수행하였다. 해석 결과, L < 1.25 m, R < 7.5 mm 에 대해, 고정된 R 값에서 L이 길어지거나 반대로 L 값이 일정할 때, R이 작아질수록 플라즈마 온도는 비례하여 증가하는 경향을 가지고 있음을 알 수 있었으며, 그 이상의 범위에서는 만족하는 플라즈마 온도 해가 없거나 2개 이상 존재하여 주어진 전류 및 전력조건에서 아크 플라즈마의 형성이 불가능하거나 불안정할 것으로 예측되었다. 이와 같은 결과를 바탕으로 입력전류가 300 A 일 때 약 15,000 K의 아크 플라즈마 온도를 안정적으로 구현할 수 있을 것이라 여겨지는 0.4 MW 급 분절형 아크 플라즈마 토치의 간극 반지름 R 및 간극팩 묶음 길이 L의 설계범위를 각각 $5.5mm{\leq}R{\leq}7.0mm$, $0.5m{\leq}L{\leq}1.0m$ 범위로 제안하였다.

• 한국해안해양공학회지
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• 제12권2호
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• pp.70-80
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• 2000

Princeton Ocean Model(POM)에서 지배방정식을 반음해법으로 차분화하여 mode splitting을 제거하고 조간대 처리기법을 도입한 3차원 semi-implicit 모델을 수립하였다 운동방정식의 순압경도력항과 수직방향 와동점 성향, 그리고 수심적분된 연속방정식의 속도발산항을 음해법으로 처리하여 빠르게 움직이는 표면중력파가 야기하는 수치안정조건을 제거하여 더 큰 time step을 사용할 수 있는 semi-implicit 모델을 수립하였다 수립한 3차원 semi-implicit 모델의 유효성과 계산휴율을 확인하기 위하여 이상적인 3차원 수로에 적용한 결과 semi-implicit 모델이 POM과 같은 결과를 주었으나 POM보다 약 4,.4배 정도 빠르게 수행되어 향상된 계산효율을 보여주었다. mode splitting 기법을 사용하는 POM의 유속 결과는 조간대에서 발생한 noise가주 수로에까지 전파되어 불안정 한 결과를 준 반면에 semi-implicit 모델결과는 더 큰 time step을 사용함에도 불구하고 조간대와 주 수로 모두에서 noiserk 없는 안정된 결과를 주었다 3차원 semi-implicit 모델의 현장 적용성을 확인하기 위하여 경기만에 적용한 결과 semi-implicit 모델이 모델 영역 전반에 걸쳐 관측된 조석 및 조류의 크기 및 전파양상을 잘 재현하였다.

• 전기학회논문지P
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• 제59권4호
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• pp.462-466
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• 2010

The purpose of this study is to evaluate the safety of a wire connector fabricated for the effective installation of a lighting fixture including its contact resistance, insulation resistance, withstanding voltage characteristics, etc., and to provide the basis for the analysis and judgment of PL(Product Liability) dispute by presenting a damage pattern due to a general flame and overcurrent. This study applied the Korean Standard (KS) for the incombustibility test of the connector using a general flame and performed an overcurrent characteristics test of the connector using PCITS (Primary Current Injection Test System). The contact resistance of the housing connector was measured using a high resistance meter and the insulation resistance was measured using a multimeter. In addition, a supply voltage of AC 1,500V for testing the withstanding voltage characteristics was applied to both ends of the connector. Measurement was performed on 5 specimens and the measured values were used as a basis for judgment. Since the connector is fabricated in the form of a housing, it can be connected and separated easily and has a structure that allows no foreign material to enter. In addition, since it has a structure that allows wires to be connected only when their polarity is identical, any misconnection that may occur during installation can be prevented. When the incombustibility test was performed by applying a general flame to the connector, it showed outstanding incombustibility characteristics and the blade and blade holder connected to the housing remained firmly secured even after the insulation sheath (PVC) was completely destroyed by fire. In addition, the mechanism of the damaged connecting wire showed a comparatively uniform carbonization pattern and it was found that some residual melted insulation material was attached to both ends. In the accelerated life test (ALT) to which approximately 500% of the rated current was applied, the connector damage proceeded in the order of white smoke generation, wire separation, spark occurrence and carbonization. That is, it could be seen that the connector damaged by overcurrent lost its own metallic color with traces of discoloration and carbonization. The contact resistance of the connector at a normal state was 2.164mV/A on average. The contact resistance measured after the high temperature test was 3.258mV/A. In addition, the insulation resistance after the temperature test was completed was greater than $10G\Omega$ and the withstanding voltage test result showed that no insulation breakdown occurred to all specimens showing stable withstanding voltage and insulation resistance characteristics.