• 한국정밀공학회지
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• 제12권11호
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• pp.140-147
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• 1995

This paper deals with conversion from the STL file to the Slice to the Slice cross-sectional information for Stereolithography. The STL file is widely used for Stereolithography, but it is very difficult to convert STL file into Slice file directly. Because it consists of an ordered list of triangular net without any topological information other than the orientation of each facet. So, The system is accomplished by data flow through several intermediate stages such as Reference. SL1. .SL2L. .SL3. and .SLC file. The data processing is performed in 5 steps: 1) Create a Reference file including common information. 2) Modify STL file within the effective range of SL machine. 3) Calculate a point of intersection between plane equation and line equation. 4) Sort z values in ascending order using quick sort algorithm. 5) Search the adjacent points and formulate a closed loop usingsingly linked linear list. The system is developed by using Borland C++ 3.1 compiler in the environment of Pentium PC, and verified to be satisfactory by making some prototypes of electric household appliances.

• 콘크리트학회논문집
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• 제12권5호
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• pp.69-80
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• 2000

This paper presents the prediction of remaining service life of the concrete due to steel corrosion caused by the following three cases; carbonation, using sea sand and using deicing salts. The assessment of initiation period was generalized considering the existing perdiction models in the literature, corrosion experiment and field assessment. To evaluate the prediction equation of rust growth, the corrosion accelerating experiments was performed. The polarization resistance was measured by potentiostat and the conversion coefficient of polarzation resistance to corrosion rate was determined by the measurement of real mass loss. Chloride content, carbonation, cover depth, relative humidity, water-cement ratio(W/C), and the use of deicing salts were taken into account and the resulting prediction equation of rust growth was proposed on the basis of these properties. The proposed equation is to predict the rust growth during any specified period of time and be effective in particular for predicting service life of concrete in the case of using sea sand.

• 치과방사선
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• 제29권1호
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• pp.161-173
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• 1999

This study was performed to compare the bone mineral densities measured at mandibular premolar area by copper-equivalent image and hydroxyapatite phantom with those measured at radius by dual energy absorptiometry and to evaluate the clinical usefulness of Digital system with slide scanner, copper-equivalent image, and hydroxyapatite phantom. For experiment. intraoral radiograms of 15 normal subjects ranged from 20 years old to 67 old were taken with copper-step wedge at mandibular premolar area and bone mineral densities calculated by conversion equation to bone mineral density of hydroxyapatite were compared with those measured at radius distal 1/3 area by Hologic QDR-1000. Obtained results as follows: 1) The conversion equation was Y=5.97X-0.25 and its determination coefficient was 0.9967. The coefficient of variation in the measurement of copper-equivalent value ranged from 4％ to 8％ and showed high reproducibility. 2) The coefficient of variation in the measurement of bone mineral density by the equation ranged from 7％ to 8％ and showed high reproducibility. 3) The bone mineral densities ranged from 0.35 to 0.79g/cm2 at mandibular premolararea. 4) The correlation coefficient between bone mineral densities at mandibular premolar area and those at radius distal 1/3 area was 0.8965. As summary, digital image analyzing system using copper-equivalent image and hydroxyapatite phantom appeared to be clinically useful to measure the bone mineral density at dental area.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권9호
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• pp.467-475
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• 1999

This paper presents an analysis method of a forward converter, using both the finite element method considering the external circuit and a state variables equation. The converter operates at 50kHz and its one period is divided into two modes for the simplicity of the analysis. In the first mode, the switching transistor turns on and an input power is transferred into the load by the electromagnetic conversion action of a ferrite transformer. In the second mode, the switching transistor turns off and the stored energy in an inductor is delivered to the load, and the transformer core is demagnetized by the reset winding current. In this paper, time-stepping finite element method taking into account the on-state electrical circuit of the converter in used to analyze both the electrical circuit and electromagnetic field of the magnetic device during the first mode and the demagnetization period of the transformer core. Then a state variables equation for the circuit which the inductor current flows is constituted and solved during the second mode. As a result, the simulation results have been good agreement with the results obtained form experiment.

• 한국동물위생학회지
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• 제45권1호
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• pp.39-45
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• 2022

The total bacteria count is significantly important factor for hygienic quality in raw milk. BactoScan FM^TM and BactoCount IBC^TM are the automated instruments for the determination of the total bacterial count in raw milk. They have been used after calibration by standard plate count (SPC) method in South Korea since 2000. It is necessary to re-evaluate for total bacterial counter according to the improvement of milk quality and the change of milk quality grade. Therefore, this study was evaluated the conversion mode of the two machines by SPC method. We collected 921 bulk-tank milk samples throughout the concentration range of 1,000~1,000,000 CFU/mL from June 2020 to October 2021. As a result, when compared by the SPC value, there was a slight difference in total bacterial count in BactoScan below 10,000 CFU/mL and above 200,000 CFU/mL and in BactoCount above 100,000 CFU/mL, respectively. Therefore, the conversion factor for BactoScan and the conversion equation for BactoCount were newly adjusted based on SPC value, and then the correlation coefficients (R²) was 0.85 or higher. In addition, the correlation (R²) between BactoScan and BactoCount was 0.91, which means the results were high positive correlation. These results are expected to contribute to improving the accuracy of the automated instruments for determining of total bacterial count in raw milk.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.170-170
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• 2010

The energy conversion from the temperature difference between hot and cold source like ocean thermal energy conversion (OTEC), requires a long and large-diameter pipe (about 1000 to 10,000 meters long) to reach the deep water. The pipe diameter ranges from 2.8 meter for proposed early test systems, to 5 meter for large, commercial power generation systems. The pipe must be designed to resist collapsing pressures produced by water temperature and density differences, and the reduced pressure required to induce flow up the pipe. Other design considerations include the external-drag effect on the pipe due to ocean currents, and the wave-induced motions of the platform to which the pipe is attached. Various approaches to the pipe construction have been proposed, including aluminum, steel, concrete, and fiberglass. More recently, a flexible pipe construction involving the use of fiberglass reinforced plastic has been proposed. This report presents the results of a scaled fixed cold water pipe (CWP) model test program performed by EES(Engineering Equation Solver) to demonstrate the feasibility of this pipe approach.

• 한국해양공학회지
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• 제13권4호통권35호
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• pp.159-168
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• 1999

부유식 파랑에너지 변환시스템(Oscillating Water Column)에 대한 해석은 입력파와 챔버, 챔버내 공기의 상호작용으로 인하여 어려움이 많다. 이 논문은 이와 같은 요소를 고려하면서도 쉽고 간편한 해석법을 제시한다. 파랑에너지에 의한 자가발전은 파랑에너지를 기계적 운동으로 변환하고 이를 전기에너지로 변환함으로써 가능하다. 본 논문은 파랑에너지에서 기계적 에너지로 변환하는 과정에 집중하여 그 부분의 성능을 해석한다. 단일 진동수 규칙파가 입력되었을 때에 파에 의하여 챔버의 상하운동이 선형적으로 발생하는 것으로 보며, 이 상하운동에 챔버내의 압력 영향을 고려하였다. 상하운동과 챔버내로 투과한 파, 그리고 챔버내 압력에 의해 발생되는 파에 의해 챔버내의 상대운동을 정하고, 그 상대 운동에 의한 공기의 압축 팽창과 온도상승을 근사적 열역학적 방정식으로 해석하였고 오리피스를 통한 유량을 결정하였다. 얻어진 식은 간단하면서도 관련요소의 영향을 전반적으로 표현한다. 결과에 따르면 고정식의 에너지 변환식은 부유식의 특별한 경우로서 파악되었다. 또한 고정식의 시스템을 그대로 부유식으로 바꿨을 때 그 변환효율은 적어지는 것으로 나타났다. 본 해석법은 계산이 간편하므로 설계단계에서 유용하게 활용될 수 있을 것으로 기대된다.

• 한국태양에너지학회 논문집
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• 제21권2호
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• pp.1-8
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• 2001

The most effective methods for utilizing solar energy are to use the sunlight and solar thermal energy such as hybrid panel simultaneously and to use concentrator. From such a view point systems using various kinds of photovoltaic panels are constructed in the world. However, there has not been a hybrid panel with a concentrator. If the sunlight is concentrated on solar cell, cell conversion efficiency increases and the temperature of the solar cell s increases. As the temperature of the solar cells increases, the cell conversion efficiency gradually decreases. For maintaining the cell conversion efficiency constant, it is necessary to keep solar cell at low temperature. In this paper, after designing a concentration rate for concentrating, we propose a model for cooling the cell and for using wasted heat. And, we compare it with conventional panels after calculating the electrical and thermal efficiency, using the energy balance equation.

• 한국태양에너지학회 논문집
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• 제32권2호
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• pp.74-86
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• 2012

For the improvement of environmental comfort in the buildings with the blind control, the objective of this study is to prevent the direct glare caused by the daylight inlet. During the process of solar profile prediction, time are significant factors that may cause error and glare during the blind control. This research proposes and evaluates the correction and control method to minimize prediction error. For the local areas with different longitude and local standard meridian, error occurred in the process of the time conversion from local standard time to apparent solar time. In order to correct error in time conversion, apparent solar time should be recalculated after adjusting the day of year and the equation of time. To solve the problems by the potential time errors, control method is suggested to divide the control sections using the calibrated fitting-curve and this method is verified through simulations. The proposed correction and control method, which considered potential time errors by loop lop leap years, could solve the problems about direct glare caused by daylight inlet on the work-plane according to the prediction errors of solar profile. And also these methods could maximize daylight inlet and solar heat gain, because the blocked area on windows could be minimized.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.463-466
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• 2001

The most effective methods of utilizing solar energy are to use the sunlight and solar thermal energy such as hybrid panel simultaneously and to use concentrator. From such a view point, systems using various kinds of photovoltaic panels were constructed in the world. However there have not been a type of panel using concentrator and hybrid simultaneously. If the sunlight are concentrated on the solar cell, cell conversion efficiency increase and the temperature of the solar cells increases. As the temperature of the solar cells increases, so cell conversion efficiency decreases. Therefore, for maintaining cell conversion efficiency at these conditions, it is necessary to keep the cell at low temperature. In this paper, after designing a concentrate rate for concentrating, we proposed model for cooling cell and using waste heat, and we compared with conventional panels after calculating the electrical and thermal efficiency using energy balance equation.