• 한국결정성장학회지
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• 제8권3호
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• pp.442-447
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• 1998

스파크 제조법으로 제조된 Ge 및 양극산화 부식법으로 제조된 다공성 Ge으로부터 청색 및 녹생 영역에서 가시광선 광발광이 관찰되었다. 자외선 조사없이 양극산화 부식법으로 제조된 다공성 Ge은 광발광 피크의 최대값이 520nm(2.38eV)에서, 자외선 조사하에서는 470nm(2,63eV)로 청색전이가 되었다. 스파크법으로 제조한 Ge은 광발광 피크가 520nm에서 관찰되었고 420nm 및 610nm에서 shoulder 피크가 나타났다. 온도감소(300K에서 20K까지)에 따른 연속적인 광발광 피크의 청색전이값은 자외선 조사하에 양극 산화부식법으로 제조한 다공성 Ge에서는 0.53meVK-1이었고 자외선 조사없이 제조한 다공성 Ge에서는 약 3배정도 큰 값인 $1.89\;meVK^{-1}$을 나타내었다. 한편 스파크 방법에 의하여 제조된 Ge은 온도 감소에 따른 연속적인 광발광 피크 청색 전이가 나타나지 않았다. 이러한 온도에 따른 광발광 현상으로부터 청색 및 녹색 광발광 현상을 나타내는 Ge의 광발광기구를 고찰하였다.

• 한국주거학회논문집
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• 제27권6호
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• pp.125-136
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• 2016

This study specifies daily behaviors that elderly residents perform in their living space and verifies the behaviors that they have difficulties in performing. The study categorized elderly people according to the level of difficulties they have when performing household activities (independence of behavior performance) and verified characteristics of the sub-behaviors and the level of difficulties of performing them in each type. For this purpose, the study conducted observation investigation on the behavior of elderly people by directly visiting houses of 52 elderly people over the age of 65. The characteristics of sub-behavior were also examined through photograph shooting and in-depth interview. In this study, behaviors of elderly people inside living space were categorized into the following nine behaviors. The study investigated the difficulties of performing these sub-behaviors according to the elderly people's level of independence by each behavior. Analyzing the difficulties of sub-behaviors according to the independence level, elderly people felt more structural problems and inconvenience in using facilities when they have lower independence level. Moving from independence to dependence, their performance of behaviors gradually became difficult, making them inevitable to use tools. At last, they came to need caregiver's help. For continuous sustenance of elderly people's independent living inside house, policy measures are required that can address the difficulties of sub-behaviors that are observed in a series of process of one's becoming dependent from independent in this study.

• 한국산학기술학회논문지
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• 제20권11호
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• pp.217-223
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• 2019

복합 형상 부품 제작 및 제작 공정의 일체화 장점으로 3D 프린팅 기술의 적용 분야가 확대되고 있으며, 지속적인 연구 개발에 의해 다양한 기술방안들이 등장하고 있다. 대표적인 기술로는 파우더 형태의 소재 위에 레이저를 조사함으로써 원하는 영역을 소결 및 적층 제작하는 방식의 SLS 기술이 있으며, 고성능의 엔지니어링 플라스틱을 활용하여 실제 사용할 수 있는 부품을 제작하는 사례가 늘어나고 있다. 본 연구에서는 활용도가 높은 고분자 소재인 폴리아미드 12 소재 및 글라스 비드가 보강된 폴리아미드 12 소재를 대상으로 인장시편을 제작하여 시편 제작 방향 및 인장 시험 온도에 따른 특성 결과를 비교 분석하였다. 시편 제작방향은 작업 평면 기준으로 0°, 45°, 90° 로 구분하였으며, 인장시험온도는 -25℃, 25℃, 60℃로 조건을 구분하였다. 시험 결과로부터 제작 방향이 90°에 가까울수록 두 소재 모두 탄성률의 미세한 감소를 보였으며, 인장강도는 PA12보다 글라스 비드 보강 PA12가 제작방향에 대한 의존성을 명확하게 보였다. 또한 시험 온도 증가에 따라 탄성률 및 인장강도의 저하를 확인할 수 있었다.

• 조명전기설비학회논문지
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• 제18권1호
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• pp.28-35
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• 2004

질소는 안정한 가스로서 잘 알려져 있지만, 해리, 여기, 선리 등의 반응이 일어나기 시작하면 활성도가 높아지게 되고 오랫동안 유지되는 특성을 갖고 있다. 이러한 반응 및 전송과정을 이용하는 예가 많은 분야에서 볼 수 있다. 현재 질소 가스만의 특성 분석 연구에 관한 보고는 상당히 부ㅈㄱ하며 이러한 부분에 대한 연구가 필요하다고 볼 수 있다. 본 연구에서는 질소 플라즈마의 특성을 상세하게 이해하기 위해, 용량 결합형 프라즈마의 1차원 유체 모델에 의한 시뮬레이션을 행하였다. 하전입자의 밀도, 공가 전계 및 전자 에너지 등의 기본적인 움직임을 혹인하고, 전기적으로 정의 가스에서는 발생？ 않는 전기적 이중층의 형성을 분석하였다. 또한 전원 전압을 300∼700 [V] 로, 압력을 0.2∼2.0 [Tow] 로 변화시켜, 그에 따른 플라즈마를 구성하는 각 입자들의 특성을 고찰하였다.

• 대한수학회보
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• 제29권1호
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• pp.125-135
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• 1992

In various viscus flow problems it has been the custom to replace the convective derivative by the ordinary partial derivative in problems for which the data are small. In this paper we consider the Benard Convection problem with small data and compare the solution of this problem (assumed to exist) with that of the linearized system resulting from dropping the nonlinear terms in the expression for the convective derivative. The objective of the present work is to derive an estimate for the error introduced in neglecting the convective inertia terms. In fact, we derive an explicit bound for the L$_{2}$ error. Indeed, if the initial data are O(.epsilon.) where .epsilon. << 1, and the Rayleigh number is sufficiently small, we show that this error is bounded by the product of a term of O(.epsilon.$^{2}$) times a decaying exponential in time. The results of the present paper then give a justification for linearizing the Benard Convection problem. We remark that although our results are derived for classical solutions, extensions to appropriately defined weak solutions are obvious. Throughout this paper we will make use of a comma to denote partial differentiation and adopt the summation convention of summing over repeated indices (in a term of an expression) from one to three. As reference to work of continuous dependence on modelling and initial data, we mention the papers of Payne and Sather [8], Ames [2] Adelson [1], Bennett [3], Payne et al. [9], and Song [11,12,13,14]. Also, a similar analysis of a micropolar fluid problem backward in time (an ill-posed problem) was given by Payne and Straughan [10] and Payne [7].

• 대한화학회지
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• 제39권5호
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• pp.384-392
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• 1995

$BiCl_3$의 승화압과 엔탈피를 370.6에서 488.8 K까지 Knudsen 유출법을 사용하여 측정하였고, 또한 438.2에서 495.7 K까지 Torsion 유출법에 의해 추가 실험을 하였다. 평형 승화압도 이 안정상태 데이터로부터 구하였다. ${\Delta}_{sub}H^0_{298.15}$와 ${\Delta}_{sub}S^0_{298.15}$의 상관관계를 이용하여, 추천할 수 있는 p(T) 식을 $BiCl_3(s)$에 의해 아래와 같이 구하였다. $BiCl_3(s); \; log(p/Pa)=－C/(T/K)\;－2.838log(T/K)－8.097{\times}10^{-2}(K/T)^2＋22.588$, 여기서 p는 파스칼, T는 절대온도, ${\Delta}_{sub}H^0_{298.15}$의 단위는 kJ $mol^{-1}$이고, $C=({\Delta}_{sub}H^0_{298.15}＋5.9988)/1.9146{\times}10^{-2}$이다. 응축상수와 그것의 온도 의존성도 위의 두 방법에 의한 실험으로부터 유도하였다.

• 한국디지털건축인테리어학회논문집
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• 제11권3호
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• pp.79-88
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• 2011

In the context of sustainability which is understood as equilibrium among three elements; human, space and time, the imbalance within the Seoul metropolitan area hinders its own area or the nation from development. Claims for the balanced development in the area are set up on the premise that there is a locational order of priority among the zones named 'overpopulation suppression', 'growth management' and 'conservation'. Based on the systematic consideration of competitiveness this study adopts the premise as a research hypothesis. Factor scales derived from the factor analysis, a kind of multivariate dependence analysis play an important role in this research process since they are measured by interval-ratio level and can be used for dependent variables in the statistical analysis. The hypothesis test carried out by means of the analysis of variance(ANOVA) concludes that the hypothesis assuming no difference in the competitiveness is rejected but the alternative hypothesis of the locational order mentioned above should be adjusted. Eigenvalues derived from the factor analysis could be used as weights for aggregate factor scales and the scales show that the priority is in the order of growth management - overpopulation suppression - conservation zones. This finding has also a significant implication that the countermeasures to cope with the lowering of the competitiveness resulted from the continuous and absolute restraints should be provided. And strategic approaches which are composed of key factors for each zone are deducted from in-depth review. (1) overpopulation suppression zone; health-welfare, educational base, public service factors, focusing on health-welfare one, (2) growth management zone; public service factor and (3) conservation zone; health-welfare, educational base factors, also focusing on health-welfare one.

• 천문학회보
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• 제42권2호
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• pp.49.1-49.1
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• 2017

Comets are one of the most primordial solar system objects that hold the information of the early days of solar system formation inside their nuclei. Orbiting the Sun, they spew such ancient materials that have been buried for many years, creating dust and gas comae. Cometary dust grains absorb and scatter sunlight radiating the continuous light, while gas molecules form the line emissions. Eachof the comets has its own light patterns, which depends on the physical and chemical properties of the dust and gas components. In this regard, spectropolarimetrycan be a powerful tool to study the properties of cometary constituents free from contamination of each other. This methodology offers a series of information on the polarization degrees of the dust and gas components as well as on wavelength dependence of the polarization degree and polarization angle of cometary dust simultaneously. Herein, we will report the results of the spectropolarimetric study of comet 2P/Encke, which is one of the well-known objects for its shortest orbital period and its prominent aging signals. We performed a spectropolarimetric observation of comet 2P/Encke in its inbound orbit using the Higashi-Hiroshima Optical and Near-Infrared Camera (HONIR) at the Higashi-Hiroshima Observatory, Japan, on UT 2017 February 21 at high phase angle of =75.7 deg. Ourstudy of this interesting comet is the first and only one done through spectropolarimetry in a referred publication. We will discuss the most recent polarimetric results of our study in terms of 2P/Encke' scurrent evolutionary status.

• 상하수도학회지
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• 제18권3호
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• pp.377-384
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• 2004

In the present study, a feasibility of an advanced oxidation process using UV/Hydrogen peroxide($H_2O_2$) system equipped with a medium pressure lamp for secondary effluent reclamation was investigated. Initial concentration of $H_2O_2$ and pH were changed to determine the optimum operation condition for the system. The removal efficiency of color was than 80% with 14.3mg/L of initial $H_2O_2$ and 5 minute of contact time in the UV/$H_2O_2$ system. The color removal was analyzed using first-order reaction equation. The dependence of rate constant (k) on initial $H_2O_2$ represented the rational relationship with maximum value. Residual $H_2O_2$ caused increase of effluent COD, since analyzing agent, dichromate, reacted with $H_2O_2$ in the sample. Therefore, excess initial concentration of $H_2O_2$ would significantly affect effluent COD measurement. At pH variation experiment, both residual $H_2O_2$ and color showed peak in the neutral pH range with the same pattern. Effect of $H_2O_2$ dose also enhanced color removal but raised residual $H_2O_2$ problem in the continuous operation UV system. In conclusion, these results indicated that medium pressure UV/$H_2O_2$ system could be used to control color in the secondary effluent for reclamation and reuse.

• 한국전자파학회논문지
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• 제27권1호
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• pp.42-49
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• 2016

본 논문에서는 지연 선로의 경로차를 이용하여 4~6 GHz의 연속파 신호를 감지하여 125 MHz의 해상도로 순시 주파수를 측정하는 순시 주파수 측정용 수신기를 설계 및 제작하였다. 수신기는 4 비트 지연 선로 구조를 가졌으며, 전력 분배기, 지연 선로, 전력 합성기, 전력 검파기, 비교기 등으로 구성되었다. 각각의 비트에 배정된 지연 선로의 주파수에 따른 경로 손실 차이를 보상하고, 전력 검파 특성의 주파수 의존성을 보정하기 위해 오프셋 전압 보상을 비교기에 적용하여 측정의 정확성을 향상시켰다.