• 한국자기학회지
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• 제6권5호
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• pp.334-339
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• 1996

도포형 자기기록매체에 있어서 자성분의 size와 특성이 자기기록 특성에 미치는 영향을 조사하기위하여 size가 다른 각각의 자성분으로 만든 도료를 이용하여 자기 tape를 제조하고 자성분의 분산성 및 전자 변환 특성을 측정하였다. 자성분의 분산성은 입자 size의 영향보다 입자의 형태 및 자성분의 표면화학특성에 크게 의존하며 자성분의 입자 size가 작아질 수록 자성분의 충진성은 향상 되고 tape의 remanence 특성과 출력 특성 및 noise 특성이 향상되어 고출력, 저 noise의 넓은 dynamic range의 출력이 나타남을 확인하였다. 따라서 고출력의 자기 tape를 제조하기 위하여는 자성분의 size, 형상, 표면화학 특성 및 자기특성이 자성분 선정의 중요한 요건임을 확인하였다.

• 설비공학논문집
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• 제9권1호
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• pp.82-91
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• 1997

R-410a and R-407c witch have the best potential among the substances being considered as R-22 alternatives were tested as "drop in" refrigerants against a set R-22 baseline tests for comparison. The performance evaluations were carried out in a psychrometric calorimeter test facility using the residential split-type air conditioner under the ARI rating conditions. Other than the use of different lubricant and a hand-operated expansion valve, one of the commercial systems was selected for the experiment. Performance characteristics were measured; compressor power, capacity, VCR, mass flow rate and COP. The tests showed that R-407c can be directly applied to the existing refrigeration system because of its similar vapor pressure and other thermopysical properties with those of R-22. However, it required change to the volume flow rate of compressor in order to achieve the similar performance with R-22 because of its relatively small VCR and capacity. Meanwhile, R-410a has too high a vapor pressure to be applied to the existing system and this feature results in relatively low COP of the system compared to that of R-22. But this could be improved by changing compressor design considering R-410a's relatively high VCR and capacity compared to those of R-22.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1099-1104
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• 2008

Recent year, mean energy consumptions of a people are higher than other country. And international oil price became over 120 dollar. This energy environment as well as energy war. Maybe, the Meteorological Administration is going to enforce scorching heatwave special report system from that come summer. Besides, 2008 summer, maximum demand power is expected by 64,240,000kW. The electric power equipment reserve rate appeared in to keep 12.5% level. Chilled water storage system witch is one of electric load administration system. Heat pump system used cooling tower heat recovery is advantage that use is possible to summer in small a public bath building. In this paper, we suggest that heat pump system by heat recovery using cooling tower when it is heating operation of ambient air temperature. To apply cooling tower heat recovery heat pump to chilled water heat storage type and achieved performance evaluation about operation. As a result, performance of heat pump system that about 121% in cooling mode, 138% in heating mode higher than KEPCO standard. And heating operation possible to ambient air temperature about $23^{\circ}C$, which of appear cooling tower outlet temperature about $13^{\circ}C$.

• Structural Engineering and Mechanics
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• 제59권2호
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• pp.313-326
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• 2016

In this study the three-dimensional nonlinear finite element method was used to analyze the stresses distribution in the adhesive layer used to joint two Aluminum 2024-T3 adherends. We consider in this study the effect of different parameters witch directly affect the values of different stresses. The experimental design method is used to investigate the effects of geometrical parameters of the single lap joint in order to achieve an optimization of the assembly with simple lap joint. As a result, it can be said that both the geometrical modifications of the adhesive and adherends edge have presented a significant effect at the overlap edge thereby causing a decrease in peel and shear stresses. In addition, an analytical model is also given to predict in a simple but effective way the joint strength and its dependence on the geometrical parameters. This approach can help the designers to improve the quality and the durability of the structural adhesive joints.

• 한국산업정보학회논문지
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• 제4권2호
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• pp.14-22
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• 1999

이 연구의 목적은 주요한 정보의 원천은 무엇이며, 정보 자원 관리에서 부딪치는 문제점을 파악하여 가능한 해결방안을 제시하는 것이다. 즉, 구체적으로 문자정보, 의사소통 그리고 정보활용기술을 통해 정보를 얻고 관리하는 데 있어 직위가 다른 경우 (책임자, 일반직원, 노조 대의원) 이 다른 원천들의 중요성을 얼마나 잘 알고 또한 인식하고 있으며 이 원천들에 대한 그들의 태도는 어떠한 가를 조사해 보려는 것이다. 연구의 결과 내부 정보 자원이 가장 중요하고 가장 많이 이용되고 있다. 정보 활용기술의 시설에 대해서는 가격은 저렴해지고 있는 반면 그 기능은 매우 향상됨에 따라 그 중요성이 증대되고 있으나, 그 사용은 쉬운 것에 제한 되고있어 경영자는 효율적 사용을 극대화 하기 위해서는 좀더 많은 관심과 철저한 교육 훈련이 있어야 함을 제시하고 있다.

• 전기학회논문지
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• 제59권11호
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• pp.2058-2065
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• 2010

This paper presents the sensor location and step estimation algorithm for personal navigation system (PNS). PNS has the disadvantage in that the position of the sensor must be fixed on a human body. Three-axis acceleration sensor is used to solve the disadvantage and to consider the real situation. We simplify the measurement data by using the band pass filter, witch It has the advantage in the detection of characteristic point. Through the detected characteristic points, it is possible to setup the parameter for the pattern detection. Depending on the sensor location, the parameters have the different type of noise covariance. Particularly, when the position of the sensor is changed, the impulse noise shows up. Considering the noise, we apply the recursive least square algorithm using the variable forgetting factors, which can classify the sensor location based on the estimated parameters. We performed the experiment for the verification of the proposed algorithm in the various environments. Through the experimental results, the effectiveness of the proposed method is verified.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5393-5397
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• 2011

본 연구는 나노튜브 제조시스템의 주요 구성요소인 압축-절단 장치가 안전한 성능을 발휘할 수 있도록 설계하는데 목적이 있다. 나노튜브의 제조에 있어서 가장 중요한 핵심기술은 튜브에 나노물질을 주입한 후 압력을 가하여 안전하게 봉합하고 전단분리 하는 것이다. 이 때 작용하는 압력과 속도가 나노튜브의 품질을 결정한다. 본 연구에서는 DC서보모터에 의하여 구동되는 압축-절단 장치의 구동력을 설계하고 이를 바탕으로 시스템을 제작한 후 시제품을 생산하는 과정을 보이고자 한다.

• Safety and Health at Work
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• 제7권2호
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• pp.102-110
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• 2016

Background: This work presents an experimental and modeling study of the electromagnetic environment in the vicinity of a high voltage substation located in eastern Algeria (Annaba city) specified with a very high population density. The effects of electromagnetic fields emanating from the coupled multi-lines high voltage power systems (MLHV) on the health of the workers and people living in proximity of substations has been analyzed. Methods: Experimental Measurements for the Multi-lines power system proposed have been conducted in the free space under the high voltage lines. Field's intensities were measured using a referenced and calibrated electromagnetic field meter PMM8053B for the levels 0 m, 1 m, 1.5 m and 1.8 m witch present the sensitive's parts as organs and major functions (head, heart, pelvis and feet) of the human body. Results: The measurement results were validated by numerical simulation using the finite element method and these results are compared with the limit values of the international standards. Conclusion: We project to set own national standards for exposure to electromagnetic fields, in order to achieve a regional database that will be at the disposal of partners concerned to ensure safety of people and mainly workers inside high voltage electrical substations.

• 한국초전도ㆍ저온공학회논문지
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• 제22권4호
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• pp.40-44
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• 2020

This paper describes the real operation of 2 kW class reverse-Brayton refrigeration system with neon as a working fluid. The refrigeration cycle is designed with operating pressure of 0.5 and 1.0 MPa at low and high pressure side, respectively. Compressor package consists of several helium scroll compressors witch are originally used for driving GM cryocooler. Three segments of plate heat exchanger are adopted to cover the wide temperature range and the refrigeration power is produced by turbo expander. The developed refrigeration system is successfully operated at its target temperature of 77 K. In experiments, all parameters such as pressure, temperature, mass flow rate and valve opening are measured to investigate characteristics during cool-down process and normal state. The difference between design and real operation is discussed with measured experimental data. At normal state of 77 K operation, the developed reverse-Brayton refrigeration system shows 1.83 kW at 68.2 K of cold-end temperature.

• 대한전자공학회논문지
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• 제23권6호
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• pp.950-956
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• 1986

In this paper, a direct addressing mode of a microprocessor is introduced to save memory capacity, and also a dedicated digital filter is constructed to speed up the filter processing and to enable an easy selection of the impulse response types. A theoretical analysis has been conducted on the errors caused by the finite word klength, rounding-off and multiplication procedures. The digital filter designed by the proposed method is made into a module which can function as a 7th-order recursive or a 14-order nonrecursive type with a simples witch operation. The proposed filter is implemented on a printed-circuit board. The frequency characteristics of this filter can be controlled by the multiplication values stored in ROMs. A low-pass, a high-pass and a band-pass filter have been designed and their frequency characteristics are verified by actual measurements. For a order higher filer, two filter modules have been cascaded into an integrated filter of 23rd-order non-recursive low-pass type and a 12th-order recursive multiband type. Their frequency characteirstics have been found to agree with the theory.