• 한국농림기상학회지
• /
• 제15권4호
• /
• pp.291-297
• /
• 2013

소규모 집수역에서 한낮 기온의 분포와 일사수광량 간 관계를 관찰하기 위해 고도 50m급 3곳, 100m급 3곳, 300m급 3곳 등 9지점의 사면에 경사향을 달리하여 무인기상관측기를 설치하고 1년간 매일 1500 기온과 직전 4시간(1100-1500) 일사량자료를 수집하였다. 운량이 0인 맑은 날에 한정하여 각 지점의 사면 일사수광량을 계산하고 1500 기온과 비교하였다. 이때 각 지점의 경사도(slope)와 경사향(aspect)은 $30{\times}30$ m 격자를 기준으로 반경이 5, 10, 15, 20, 25, 30개 격자로 평활화 하여 사용하였다. 1500 기온에 미치는 직전 4시간 일사수광량 간에는 통계적으로 유의한 회귀관계가 인정되었으며, 반경 25개 격자(750m)로 평활화한 경우 사면 기온변이의 54%를 설명할 수 있었다(y = 0.8309x + 0.0438, $r^2$ = 0.5444).

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
• /
• pp.197-200
• /
• 2001

In this letter, we report on the investigation of Ni/Si/Ni Ohmic contacts to n-type 4H-SiC. Ohmic contacts have been formed by a vacuum annealing and $N_2$ gas ambient annealing method at $950^{\circ}C$ for 10 min. The specific contact resistivity ( $\rho_{c}$ ), sheet resistance($R_s$), contact resistance($R_c$), transfer length($L_T$) were calculated from resistance($R_T$) versus contact spacing(d) measurements obtained from 10 TLM(transmission line method) structures. The resulting average values of vacuum annealing sample were $\rho_{c}=3.8{\times}10^{-5}\Omega cm^{3}$, $R_{c}=4.9{\Omega}$, $R_{T}=9.8{\Omega}$ and $L_{T}=15.5{\mu}m$, resulting average values of another sample were $\rho_{c}=2.29{\times}10^{-4}\Omega cm^{3}$, $R_{c}=12.9{\Omega}$ and $R_{T}=25.8{\Omega}$. The physical properties of contacts were examined using X-Ray Diffraction and Auger analysis, there was a uniform intermixing of the Si and Ni, migration of Ni into the SiC.

• Journal of Astronomy and Space Sciences
• /
• 제21권4호
• /
• pp.275-282
• /
• 2004

2004년 6월부터 7월까지 총 13일간 레몬산천문대의 1m 망원경과 BVR 필터를 사용하여 접촉 쌍성 CK Boo의 광도곡선을 완성하고, 4개(주극심 3개, 부극심 1개)의 새로운 극심시각을 산출하였다. 1998년에 개정한 Wilson-Devinney 쌍성모델의 접촉모드를 이용하여, 우리의 BVR 광도곡선과 Rucinski & Lu(1999)의 시선속도곡선을 분석하였다. 그 결과, 우리는 CK Boo가 질량비(q=0.11)와 궤도 경사각($i=65^{\circ}$)이 작은 A형 과접촉쌍성($f=84\%$)임을 확인하였다. 우리의 측광 및 분광학적 해로 부터 이 쌍성계의 절대 물리량을 $M_1=1.42Me{\odot},\;M_2=0.15M{\odot},\;R_1=1.47R{\odot}$, 그리고 $R_2=0.59M{\odot}$으로, 거리를 129pc으로 산출하였다. 우리가 구한 거리는 Hipparcos 삼각시차에 의한 거리($157{\pm}33pc$)와 오차의 범위 내에서 일치한다.

• 한국인터넷방송통신학회논문지
• /
• 제19권1호
• /
• pp.203-209
• /
• 2019

본 연구에서는 WENNER 4전극법 기반에 GMD(신규 대지 고유 저항 측정 장치)와 측정용 Probe(접지동봉)가 PLC(전력선 통신)로 연결된다. 측정용 Probe는 2개(P1,P2)가 1조로 모두 5조 10개의 Probe가 직렬로 각각 1m, 2m, 4m, 8m, 16m 간격으로 대지(토양)에 설치되어 있다. GMD에서 보낸 PLC 신호를 측정용 Probe 1조(P1)의 수신기가 감지하면 Probe에 부착된 PSD(전력 공급 장치)에서 측정용 미세 전압과 전류가 대지로 흐르게 되고 P1과 P2 사이의 토양을 거쳐 Probe 1조(P2)에 유입 된다. 이때 대지 저항으로 인해 전압 강하가 발생되는 원리로 저항값을 측정하게 된다. 이렇게 1~5조까지 T초 간격으로 대지 저항을 측정하고 측정된 데이터는 메인 장비에 탑재된 Arduino Server에 저장 한다. 저장된 측정 데이터는 옴의 법칙(Ohm's Law)에 의한 수식 R=E/I와 고유저항 ${\rho}=6.28aR$ (여기서, R: 측정저항, E: 측정전압, I: 측정전류, a:Probe 간격, ${\rho}$: 고유저항 )를 통해 고유저항을 얻을 수 있다. 실시간으로 얻어진 데이터를 Main PC에 설치된 CDGES 프로그램과 연동되어 데이터 분석이 가능하게 되고 대지(토양)의 접지 환경을 실시간 모니터링 할 수 있게 된다. 또한, 대지(토양)의 온도, 습도 등 계절의 특성을 파악하여 3D 그래프 지원으로 입체적인 Display가 가능하다. 연구의 한계점은 실험적으로 개발 운용한 모델로 상업적인 접근을 위해 Test Bed의 구체적인 적용 방안이 필요할 것이다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제11권3호
• /
• pp.169-181
• /
• 2011

In this present paper, a comprehensive drain current model incorporating the effects of channel length modulation has been presented for multi-layered gate material engineered trapezoidal recessed channel (MLGME-TRC) MOSFET and the expression for linearity performance metrics, i.e. higher order transconductance coefficients: $g_{m1}$, $g_{m2}$, $g_{m3}$, and figure-of-merit (FOM) metrics; $V_{IP2}$, $V_{IP3}$, IIP3 and 1-dB compression point, has been obtained. It is shown that, the incorporation of multi-layered architecture on gate material engineered trapezoidal recessed channel (GME-TRC) MOSFET leads to improved linearity performance in comparison to its conventional counterparts trapezoidal recessed channel (TRC) and rectangular recessed channel (RRC) MOSFETs, proving its efficiency for low-noise applications and future ULSI production. The impact of various structural parameters such as variation of work function, substrate doping and source/drain junction depth ($X_j$) or negative junction depth (NJD) have been examined for GME-TRC MOSFET and compared its effectiveness with MLGME-TRC MOSFET. The results obtained from proposed model are verified with simulated and experimental results. A good agreement between the results is obtained, thus validating the model.

• Structural Engineering and Mechanics
• /
• 제90권2호
• /
• pp.143-157
• /
• 2024

Cold-formed steel (CFS) I sections are increasingly being used as load-bearing components in building constructions, and such I sections frequently incorporate web holes to facilitate service installation. The economical and structural advantages of these elements have prompted many researchers to investigate the behavior of such structures. Despite numerous studies on the buckling stability of castellated beams, there is a notable absence of experimental investigation into oval castellated beams with stiffeners. This study examines the local buckling of cold-formed steel castellated I-beams stiffened with oval constellations through experimental and numerical analysis. Four specimens are fabricated with and without stiffeners, including parallel, perpendicular, and intersecting types attached to the web portion of the beam, along with cross stiffeners for the oval-shaped openings at the beam ends. Additionally, a numerical model is developed to predict the behavior of castellated beams with oval openings up to failure, considering both material and geometric nonlinearities. Codal analysis is performed using the North American specification for cold-formed steel AISI S-100 and the Australian/New Zealand design code AS/NZS 4600. The anticipated outcomes from numerical analysis, experimental research, and codal analysis are compared and presented. It will be more helpful to the preliminary designers.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1560-1565
• /
• 2003

Tapping mode atomic force microscopy (TM-AFM) utilizes the dynamic response of a resonating probe tip as it approaches and retracts from a sample to measure the topography and material properties of a nanostructure. We present recent results based on nonlinear dynamical systems theory, computational continuation techniques and detailed experiments that yield new perspectives and insight into AFM. A dynamic model including van der Waals and Derjaguin-Muller-Toporov (DMT) contact forces demonstrates that periodic solutions can be represented with respect to the approach distance and excitation frequency. Turning points on the surface lead to hysteretic amplitude jumps as the tip nears/retracts from the sample. Experiments are performed using a tapping mode tip on a graphite sample to verify the predictions.

• Structural Engineering and Mechanics
• /
• 제57권1호
• /
• pp.65-89
• /
• 2016

This paper presents the development of methodologies using Extended Finite Element Method (XFEM) for cracked unstiffened and concentric stiffened panels subjected to constant amplitude tensile fatigue loading. XFEM formulations such as level set representation of crack, element stiffness matrix formulation and numerical integration are presented and implemented in MATLAB software. Stiffeners of the stiffened panels are modelled using truss elements such that nodes of the panel and nodes of the stiffener coincide. Stress Intensity Factor (SIF) is computed from the solutions of XFEM using domain form of interaction integral. Paris's crack growth law is used to compute the number of fatigue cycles up to failure. Numerical investigations are carried out to model the crack growth, estimate the remaining life and generate damage tolerant curves. From the studies, it is observed that (i) there is a considerable increase in fatigue life of stiffened panels compared to unstiffened panels and (ii) as the external applied stress is decreasing number of fatigue life cycles taken by the component is increasing.

• 천문학회보
• /
• 제36권1호
• /
• pp.28.1-28.1
• /
• 2011

We observed the transiting exoplanet, TrES-2b, with 1.5m telescope at Maidanak Observatory in Uzbekistan. We observed TrES-2 system for six nights, which contained two orbital periods of the planet. Therefore, we obtained the entire light curve of TrES-2b, which covered not only the whole primary transit containing both ingress and egress part, but also non-transit region. We used both R and Y band filters. Especially, Y filter is used first for transit observation and covers relatively longer wavelength ($1.02{\mu}m$ of center wavelength), to provide the light curve less affected by limb darkening. By fitting best model light curve for the obtained one, we determined these observables, transit depth, transit length, and planet's orbital period, which led to the determination of five physical parameters, stellar radius R*, stellar mass M*, inclination i, semi-major axis a, and planetary radius Rp. We will discuss of these results.

• 대한간호
• /
• 제30권4호
• /
• pp.61-68
• /
• 1991

This study was conducted to testing the criterion - related validity of a mental health assessment tool which developed based on a korean culture. Criteria scale for this tool were MMPI and CMI(M - R). The study subject were 100 male and female aged 20 or more with quota sampling. The data was collected from August 16. to August 26. 1989. The data obtained from 85 subjects were analysed using S.P.S.S.(Stastistical Package for the Social Science). As a result, there are no significant correlation between Mental Health Assessment Tool and MMPI and CMI except Mf(Masculinity-Feminity) Subscale of MMPI. This result means the MMPI and CMI was not related to tool which developed based on medical model from etic perspectives, although the tool which had been developed in America Modified to Korean situation. So I dare to say that only the absence of mental illness does not means mental health and the diagnosis of mental illness is not the only criteria of a mental health.