• 한국항행학회논문지
• /
• 제12권2호
• /
• pp.170-179
• /
• 2008

본 연구는 기존의 건설기업 정보화 수준평가 관련 연구에서 나타나고 있는 연구의 한계점과 건설기업 정보화 특성을 고려하여 건설기업의 경영목표에 따라 정보화 수준을 측정할 수 있는 모형을 설계하였다. 세부적으로 건설기업의 업무특성과 새로운 건설 정보화 수준 평가모형 개발을 위한 요구사항을 정리하고, 이러한 요구사항을 만족시키기 위한 정보화 수준 평가모형의 구성요소 및 측정방법을 설계하였다. 개발된 건설기업 정보화 수준모형은 전문가 집단을 대상으로 델파이 방법과 함께 국내 200개 건설기업을 대상으로 설문조사를 실시하여 통계적 방법을 통하여 정보화 수준평가 모형의 적합성(신뢰성 및 타당성)을 검증하였다. 본 연구의 결과는 건설기업의 경영목표를 개선하기 위한 정보화 추진전략을 수립하는데 활용될 수 있을 것으로 기대된다.

• ETRI Journal
• /
• 제38권2호
• /
• pp.265-271
• /
• 2016

We analyzed the interface characteristics of Zn-based thin-film buffer layers formed by a sulfur thermal cracker on a $Cu(In,Ga)Se_2$ (CIGS) light-absorber layer. The analyzed Zn-based thin-film buffer layers are processed by a proposed method comprising two processes - Zn-sputtering and cracker-sulfurization. The processed buffer layers are then suitable to be used in the fabrication of highly efficient CIGS solar cells. Among the various Zn-based film thicknesses, an 8 nm-thick Zn-based film shows the highest power conversion efficiency for a solar cell. The band alignment of the buffer/CIGS was investigated by measuring the band-gap energies and valence band levels across the depth direction. The conduction band difference between the near surface and interface in the buffer layer enables an efficient electron transport across the junction. We found the origin of the energy band structure by observing the chemical states. The fabricated buffer/CIGS layers have a structurally and chemically distinct interface with little elemental inter-diffusion.

• Journal of Advanced Marine Engineering and Technology
• /
• 제36권6호
• /
• pp.808-813
• /
• 2012

본 연구는 정방형주의 후류측으로 분리된 분할판(Detached splitter plate)을 설치한 경우 정방형주의 항력저감특성을 분할판의 폭과 정방형주 후면에서부터 분할판까지의 간격을 변수로 하여 양 항력측정 실험으로 파악한 것이다. 그 결과를 요약하면 다음과 같다. 양 항력의 시간변화를 측정해 본 결과 정방형주의 후류측에 분리된 분할판을 설치한 경우가 본래의 정방형주에 비해 양력의 진폭이 대폭 감소했다. 분할판의 폭비를 고정시킨 경우 정방형주의 항력감소율은 간격비가 증가할수록 증가하다 감소하는 특성을 보였다. 같은 간격비에서는 분할판의 폭비가 클수록 정방형주의 항력감소율이 컸으며, 폭비 H/B=1.5, 간격비 G/B=0.5에서 최대 24.2%의 항력감소율을 보였다.

• 경영정보학연구
• /
• 제7권1호
• /
• pp.81-96
• /
• 2005

웹사이트의 사용이 일상화 되어감에 따라 컴퓨터를 다루기 힘든 장애인 및 노인들의 웹사이트 정보에 대한 접근성이 강조되고 있다. 노인과 장애인의 정보화 격차를 해소하기 위해 웹 접근성에 대한 인식이 중요시되고 있으나 한국에서는 이와 관련된 분야의 연구가 미미한 실정이다. 본 연구에서는 지금까지의 웹 접근성에 관한 선행 연구와 접근성 평가도구를 분석하여 기존의 웹 접근성 평가의 한계를 지적하고 이를 해결하기 위한 웹사이트 접근성 평가모델을 제안하였다. 특히 웹 접근성 평가방법을 다각적으로 시도하기 위해 1차 평가에서는 자동화 평가도구인 A-Prompt를 이용하였고, 2차 평가에서는 1차 결과를 중심으로 소스분석과 HPR(Home Page Reader) 스크린리더를 통한 수작업(메뉴얼) 평가를 실시하였다. 평가결과를 바탕으로 접근성 오류율을 계산하여 한국과 미국정부 웹사이트의 접근성을 비교분석하고 평가결과를 통해 시사점과 개선방안을 제시하였다.

• 동력기계공학회지
• /
• 제15권2호
• /
• pp.13-18
• /
• 2011

This thesis is about the result of conducting a specific experiment for the development of noncontact vibration displacement sensor for measuring the spindle vibration that is used for conditional monitoring of machinery. One should be careful when using the eddy current type displacement sensor because the sensitivity of it is different according to the quality of the material. While the probe used for nondestructive inspection adopts the effect of transmitting the material by using the high frequency domain, the eddy current type displacement sensor uses the lower frequency of around 1MHz. Also, while the nondestructive probe uses the method of enhancing output by using the resonance zone, the vibration displacement sensor utilizes the stable zone by avoiding the resonance zone. Since the oscillator of the converter uses the "L" element as Probe, its characteristic changes with the variation of a relevant impedance. In other words, if the length of Probe's Cable gets extended (Impedance increase), the sensitivity declines accordingly. The effect of surrounding temperature was small, but the influence of the quality of Sensor Coil used was high. Moreover, following an experimental demonstration of the phenomenon where the sensitivity decreases as the frequency of the tested material increases from a frequency response test, the maximum frequency that could be measured was approximately 1KHz. It was noted that the degree of precision could be maintained by using the gap of the probe in the linear zone at the installation site.

• 한국기계가공학회지
• /
• 제19권2호
• /
• pp.89-96
• /
• 2020

In this study, we developed a finite element model for the built-in bottom-freezer type refrigerator and then used the structural analysis method to analyze and evaluate the deflection of the doors. We tested the validity of the developed analytical model by measuring the deflection of the hinge when loads were applied to the upper and lower hinges of the refrigerating compartment and compared these with the analysis results. The comparison of the vertical displacement of the measured result and the analysis result showed an error ratio of up to 12.8%, which indicates that the analytical model is consistent. Using the analytical model composed of the cabinet, hinges and doors, we performed analyses for two cases: both doors closed, and the refrigerating door open. Since the maximum vertical displacement of the refrigerating compartment door (R-door) with the food load is smaller than the gap between the lower surface of the R-door and the upper surface of the freezer compartment door (F-door), it is judged that the R-door and the F-door do not contact when the doors are opened or closed. In addition, the analysis result showed that the difference between the vertical displacement at the hinge on the opposite side and the hinge side of the R-door is favorably smaller than the management criterion of the refrigerator manufacturer.

• 한국정밀공학회지
• /
• 제34권1호
• /
• pp.41-46
• /
• 2017

Magnetically levitated (Maglev) vehicles maintain a constant air gap between guideway and car bogie, and thereby achieves non-contact riding. Since the straightness and the flatness of the guideway directly affect the stability of levitation as well as the ride comfort, it is necessary to monitor the status of the guideway and to alert the train operators to any abnormal conditions. In order to develop a signal processing algorithm that extracts guideway irregularities from sensor data, virtual testing using a simulation model would be convenient for analyzing the exact effects of any input as long as the model describes the actual system accurately. Simulation model can also be used as an estimation model. In this paper, we develop a state-space dynamic model of a maglev vehicle system, running on the guideway that contains jumps. This model contains not only the dynamics of the vehicle, but also the descriptions of the power amplifier, the anti-aliasing filter and the sampling delay. A test rig is built for the validation of the model. The test rig consists of a small-scale maglev vehicle, tracks with artificial jumps, and various sensors measuring displacements, accelerations, and coil currents. The experimental data matches well with those from the simulation model, indicating the validity of the model.

• 센서학회지
• /
• 제1권2호
• /
• pp.147-154
• /
• 1992

본 논문은 생체 신호를 얻기 위한 생체삽입형 8-채널 바이오텔레메트리 시스템을 설계하였다. 본 시스템의 내부회로는 가능한 한 소형이고 저소비 전력화하였을 뿐만아니라 synchronization gap을 주기로 생채신호의 연속측정을 가능하도록 설계하였다. 본 시스템의 주된 기능은 생체신호 연속측정과 외부회로의 적절한 명령에 의해 생체 삽입 전지를 On, off하여 소비전력을 줄일 수 있도록 하였다. 또한 체내 삽입시스템을 집적화하기 위해 람다룰을 기본으로 한 $2{\mu}m$ n-well 설계규칙에 의해 레이아웃을 수행하였다. 그러므로 국내에서 개발되고 있는 압력센서나 ISFET 등을 본 시스템과 함께 삽입하여 생체신호, 즉 심전도, 혈류량, 혈압 등을 측정해 외부로 전송하는 의용 텔레메트리 시스템이 기대된다.

• Progress in Superconductivity
• /
• 제8권2호
• /
• pp.143-151
• /
• 2007

Accurate measurements of the microwave surface resistance (Rs) of high temperature superconductor (HTS) films are important with regard to applications of HTS materials for wireless communications. As the surface resistance values of HTS films are usually extracted from the measured unloaded quality factor ($Q_0$) of resonators made of HTS films, it is essential to measure the resonator $Q_0$ with accuracy. The $TE_{011}\;mode\;Q_0$ of sapphire resonators with the endplates made of $YBa_2Cu_3O_{7-{\delta}}$(YBCO) film on $LaAlO_3$ is measured by using the S-parameter circle-fit method at a frequency of about 19.6 GHz and temperatures of 30 K to 90 K, which is compared with the measured values by using the Lorentzian-fit method. Good agreements are found between the two sets of $Q_0$ values measured by using the two different methods whether the resonator is used in a weak-coupling scheme or a strong-coupling scheme, showing reliability of both methods fur measuring the resonator $Q_0$ accurately. The $Q_0$ of sapphire resonators with a gap between the top plate and the rest of the resonator is also discussed.

• 한국환경농학회지
• /
• 제39권3호
• /
• pp.228-236
• /
• 2020

BACKGROUND: The closed chamber method is the most commonly used for measuring greenhouse gas emissions from rice fields. This method has the advantages of being simple, easily available and economical. However, a measurement result using the chamber method is an estimated value and is complete when the uncertainty is estimated. The methane emissions from a rice paddy account for the largest portion of the greenhouse gas emissions in the agriculture sectors. Although assessment of uncertainty components affecting methane emission from a rice paddy is necessary to take account of dispersion characteristics, research on these uncertainty components is very rare to date. The goal of this study was to elucidate influencing factors on measurement uncertainty of methane concentrations measured by a closed automated chamber system from a rice paddy. METHODS AND RESULTS: The methane sampling system is located in the rice paddy in Gyeonggi-do Agricultural Research and Extension Services (37°13'15"N, 127°02'22"E). The primary measurement uncertainty components influencing methane concentrations (influencing factors) investigated in this research were repeatability, reproducibility and calibration in the aspects of methane sampling and analytical instrumentation. The magnitudes of the relative standard uncertainty of each influencing factor were quantified and compared. CONCLUSION: Results of this study showed what influencing factors were more important in determination of methane concentrations measured using the chamber system and analytical instrumentation located in the monitoring site. Quantifying the measurement uncertainty of the methane concentrations in this study would contribute to improving measurement quality of methane fluxes.