• 대한기계학회논문집
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• 제13권4호
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• pp.708-716
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• 1989

본 연구의 목적은 고속도 카메라로 촬영된 순간사진들로부터 액주면의 파장, 진폭, 파의 진행속도 및 교란의 성장속도 등을 측정하여 액주의 분열에 미치는 기류 및 액량의 효과를 구하였고, 또 이것을 선행 연구자들의 이론 및 실험과 비교분석하여 액주의 분열 기구를 밝히는 데 있다.

• 한국주조공학회지
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• 제33권4호
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• pp.157-161
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• 2013

A ribbon-type polycrystalline silicon wafer was directly fabricated from liquid silicon via a novel technique for both a fast growth rate and large grain size by exploiting gas pressure. Effects of processing parameters such as moving speed of a dummy bar and the length of the solidification zone on continuous casting of the silicon wafer were investigated. Silicon melt extruded from the growth region in the case of a solidification zone with a length of 1cm due to incomplete solidification. In case of a solidification zone wieh a length of 2 cm, on the other hand, continuous casting of the wafer was impossible due to the volume expansion of silicon derived from the liquid-solid transformation in solidification zone. Consequently, the optimal length of the solidification zone was 1.5 cm for maintaining the position of the solid-liquid interface in the solidification zone. The silicon wafer could be continuously casted when the moving speed of the dummy bar was 6 cm/min, but liquid silicon extruded from the growth region without solidification when the moving speed of the dummy bar was ${\geq}$ 9 cm/min. This was due to a shift of the position of the solid-liquid interface from the solidification zone to the moving area. The present study reports experimental findings on a new direct growth system for obtaining silicon wafers with both high quality and productivity, as a candidate for an alternate route for the fabrication of ribbon-type silicon wafers.

• 한국소음진동공학회논문집
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• 제20권2호
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• pp.185-190
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• 2010

Condition monitoring(CM) is a method based on non-destructive test(NDT). So, recently many kind of NDT were applied for CM. Acoustic emission(AE) is widely used for the early detection of faults in rotating machinery in these days because of high sensitivity than common accelerometers and detectable low energy vibration signals. And crack is considered one of severe fault in the rotating machine. Therefore, in this paper, study on early detection using AE has been accomplished for the crack of the low-speed shaft. There is a seeded initial crack on the shaft then the AE signal had been measured with low-speed rotation as the applied load condition. The signal detected from crack in rotating machine was detected by the AE transducer then the trend of crack growth had found out by using some of feature values such as peak value, skewness, kurtosis, crest factor, frequency center value(FC), variance frequency value(VF) and so on.

• 한국주조공학회지
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• 제11권4호
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• pp.303-313
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• 1991

The Purification mechanism of high purity aluminum was studied through the variation of stirring speed and coolant flow rate in the stirring method. In the stirring method the degree of purification was changed as the following factors;the variation of diffusion boundary layer thickness the variation of growth rate and the solute concentration of the residual melt. The concentration of Fe and Si was decreased as the stirring speed and the radial distance increased. In a high stirring speed of 2000rpm with unidirectional stirring mode, the uniformity of solutes was obtained. On the other hand, the purification of Si was done by the combinations of stirring method, fractional melting and acid leaching. In the case of Si purification, the centrifugal force developed in the melt acted as the significant purification factor. It was possible to obtain the purified 3N grade Si crystal after the complete elimination of residual aluminum by fractional melting and acid leaching.

• 한국통신학회논문지
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• 제29권12B호
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• pp.1013-1021
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• 2004

정보통신과 방송분야의 디지털화가 급속하게 진전되고 미디어의 전송능력이 비약적으로 광대역화, 고속화 함으로써 통신과 방송의 융합문제가 대두되고 있다. 이를 실현하기 위하여 정부에서는 광대역통합망(BcN)의 구축을 국가의 중요한 신성장동력으로 선정하였다. 이 광대역통합망은 FTTH를 기반으로 구축될 것이며 이 솔루션에 의 의하여 광대역 흠네트워크가 실현될 것이다. 통신과 방송의 융합을 목표로 구축되는 BcN형 흠네트워크는 어느정도의 전송속도와 대역폭을 요구할 것인가. 가정당 전송속도를 설정하기 위하여는 홈네트워크의 범위와 BcN의 구성방식을 명확하게 정리해야 한다. 공동주택이냐 단독주택이냐에 따라 FTTH를 구축할 때 적용할 통신과 방송의 융합기술방식이 다르고 네트워크 모형도 달라진다. 그리고 홈네트워크의 범위도 건물내부망과 홈내부망으로 정하여 구간마다 요구되는 전송속도를 제시할 필요가 있다. 이 논문에서는 이런점을 고려하여 BcN형 흠 네트워크의 전송속도를 제시하고자 한다.

• 한국작물학회지
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• 제69권1호
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• pp.15-24
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• 2024

Environmental factors play an important role in crop growth and development. In recent years, climate change has become a challenge that limits environmental factors. Light is an important environmental factor for photosynthesis in rice. In addition, temperature is one of the most important factors for rice production; thus, a 1℃ increase in temperature because of climate change can affect rice growth and development. Therefore, we investigated the effect of shading on the growth characteristics of rice under different temperature conditions from the vegetative stage to the flowering stage. Plants were grown at three different temperatures: 26℃/16℃ for 21℃, 29℃/19℃ for 24℃, and 22℃/32℃ for 27℃ in a phytotron. A 55% shade treatment was applied after 10 days of transplanting until the flowering stage. Plant height was not affected by the shading treatment. In the maximum tiller number response to shading, a lower tiller number and growth speed of tiller was found in the 27℃ condition. Among leaf characteristics, shading increased the flag leaf area, length, width, and effective leaf area; however, it decreased the leaf number on the main stem, especially at 27℃. In terms of stem characteristics, shading affected culm wall thickness in both varieties. Finally, regarding the panicle characteristics, lower panicle numbers, spikelet numbers per panicle, primary numbers, and secondary numbers per panicle were found under the shading treatment. Most of the desirable characteristics were affected by the shading treatment at 27℃. Overall, these results indicated that shading had a greater effect on rice plant growth at high temperature.

• 융합경영연구
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• 제6권3호
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• pp.14-25
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• 2018

Purpose - Taxes cover all aspects of society, especially in terms of resource allocation and economic growth. In reality, the tax revenue is often used to measure the quality of a country's economy. The relationship between tax revenue and economic growth has been paid much attention by academic circles. Due to this background, this paper attempts to investigate the mutual effect between tax revenue and economic growth. Research design, data, and Methodology - The annual datum form 1980 to 2017 are employed to conduct an empirical analysis under the vector error correction model. In this paper, the GDP is treated as an independent variable. The tax revenue is treated as a dependent variable. Furthermore, a menu of statistic approaches will be used to testify the mutual effect between tax revenue and economic growth. Results - Via the co-integration test, the results report that the tax revenue has a positive effect on economic growth in the long run. Through the vector error correction estimation, the results also report that the tax revenue also has a positive effect on economic growth in the short run. Conclusions - This paper provides a view that the tax revenue is a kind of a determinant to promote economic growth. Therefore, the China's government should pay much attention to the improvement of tax revenue system so as to maintain a high-speed economic growth.

• 생물환경조절학회지
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• 제7권1호
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• pp.9-14
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• 1998

본 연구에서는 인공광하의 풍동내에서 기류속도와 생육실내의 위치가 플러그묘 개체군의 생장에 미치는 효과를 분석하였다 기류속도가 증가하면 모개체군내에서의 상대습도는 감소하나, 포차는 증가한다. 이에 따라 증산이 활발하게 이루어져 잎에서의 수분포텐셜이 저하되며 묘개체군 위에서 공기역학적 저항이 감소함에 따라 확산계수가 높게 나타난다. 그 결과로서 0.93m.s$^{-1}$의 기류속도에서 줄기 길이, 줄기직경에 대한 줄기 길이의 비, 초장, 엽수는 유의성이 인정될 만큼 작게 나타났다. 묘개체군의 순광합성속도는 기류속도의 증가와 함께 증가되면서 0.7~0.9 m.s$^{-1}$에서 높게 나타났다. 생육실내의 위치 즉 기류의 진행방향을 따라 줄기 직경과 지하부 건물 중은 감소하였으나, 줄기 직경에 대한 줄기 길이의 비와 엽면적은 증가하는 것으로 나타났다. 이밖에 플러그묘의 생체중 또는 건물 중에 대한 T/R비는 기류속도의 변화와 무관하게 각각 2.8~3.5, 3.2~3.9로서 비슷하게 나타났으나, 건물율은 지상부에서 8.1~9.4, 지하부에서 10.1~10.9로서 지하부에서 다소 높게 나타났다. 그러므로 기류속도의 크기와 기류의 진행방향에 따라 묘개체군 위에서의 확산계수가 다르게 나타나며 이로 인하여 모개체군의 생장 차이가 나타남을 알 수 있다. 따라서 식물모공장과 같이 인공광을 이용한 반폐쇄 식물생산 시스템에서 품질이 균일한 모를 생산하려면 묘개체군의 미기상에 기초한 적정 환경조건의 확립이 요구된다.

• 한국재난정보학회 논문집
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• 제19권3호
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• pp.608-623
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• 2023

연구목적: 최근 물류 창고 수의 증가 추세에 있다. 또한 이러한 물류 창고의 수가 늘어남에 따라 화재발생건수 또한 매년 증가 추세를 보여 대형 물류 창고에서 발생하는 화재 예방의 중요성이 커지고 있다. 연구방법: 물류 창고에 적응성 있는 화재감지기로 대두되고 있는 공기흡입형 감지기에 대해 조사하고 화재시뮬레이션(FDS)를 통해 물류 창고 모델링을 진행하여 물류창고 화재 성장 속도 4단계와 화원 위치 3가지에 따른 일반 연기감지기와 공기흡입형 감지기의 감지 속도를 비교 분석하였다. 연구결과: 성장속도 Slow급 화재와 Medium급 화재에서는 화원위치에 상관없이 공기흡입형 감지기의 감지속도가 더 빨랐다. 하지만 Fast급 화재와 Ultra Fast급 화재에서는 화원위치에 따라 일반연기감지기의 감지속도가 더 빠른 것을 확인할 수 있었다. 결론: 공기흡입형 감지기는 화재성장속도가 빨라질수록, 둘째 화원의 위치가 공기흡입형 감지기 수신부보다 멀어질수록 같은 위치에 있는 연기감지기보다 성능이 낮아지는 것을 확인할 수 있었다. 그렇기에 화재성장속도가 빠른 가연물을 적치하는 창고에서는 공기흡입 형 감지기를 설치하더라도 공기흡입형 감지기의 수신부와 멀리 떨어진 위치에는 연기감지기를 추가로 부착하는 것이 화재 안전성을 높이는 방법이라고 판단된다.

• 한국진공학회지
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• 제8권3B호
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• pp.327-332
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• 1999

High speed real-time spectroscopic ellipsometry was employed in order to characterize the growth of chromium thin film. This instrument can collect 512 points of {$\Delta$(hv), $\Psi$(hv)} spectra from 1.3 to 4.5 eV with acquisition and repetition rates of 20 msec or less. When this instrument was integrated into the chromium thin film growth, we could obtain not only the information on film properties but also the details of the processes. We deduced the growth rates and the evolution of the optical properties of chromium thin films under several preparation conditions. We also demonstrated the contamination process of chromium thin films caused by air exposure.