• Macromolecular Research
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• v.14 no.6
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• pp.640-645
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• 2006

Polyethylene of bimodal molecular weight distribution was irradiated with an electron beam. The thermal and mechanical properties were examined by DSC, small and wide angle X-ray scattering and static tensile test according to the crystal morphology of the irradiated samples. The crystal morphology change upon irradiation, as revealed by wide angle X-ray scattering, correlated well with the changes in melting enthalpy, whereas the lamellar thickness and the amorphous gap thickness remained virtually unchanged at irradiation doses up to 500 kGy. Crosslinks in the crystal domains became evident at an energy level of 250 kGy, resulting in reduced crystallinity and crystal size of the (110) and (200) planes. The samples became stiff and brittle with increased irradiation dose, which seem to be more relevant to the amount of cross links than the crystal morphology changes.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.4
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• pp.80-86
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• 1999

The purpose of this study was to suggest a case study and anlaysis of the visual impact in dam construction through visual impact assessment method in Dong-sang river. The results can be summarized as follows; 1) For the evaluation of the visual impact of dam construction, five steps such as field analysis of visual status, finding visual sensitivity area and visual control point, making visual simulation material and evaluation, and visual impact analysis and assessment were suggested as desirable. 2) In the case study, the visual impact of dam construction was evaluated to be simple, unique, modern, static, cool and unfamiliar. 3) There was a few difference between the pre-construction and post-construction in statistical test. Especially, The dam in Man-Jee area was evaluated to be artificial, unique and destroyed in statistical difference, and then we design dam structure with visual friendliness. 4) In conclusion, there was high correlation between pre-construction landscape and post-construction landscape through semantic differential scale method using eleven adjectives. Therefore, we state that there is no visual impact for the dam construction for the moment.

• The Transactions of the Korea Information Processing Society
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• v.5 no.5
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• pp.1300-1310
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• 1998

Web Information Systems have many static HTML documents and dynamic CGI application programs. A hyperlinked information environment on Web systems include lots of mutually referenced documents. This cause problems of data consistency in a intra-document and among inter-documents. To solve the problems, we propose a management method of Web system which have hierarchical information structure, and an unified problem-solving approach. We construct a large scale practical Web system based upon the proposed architecture. The proposed results can provide many advantage to WebMasteters.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.263-266
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• 2005

실시간 시스템은 시간적 정확성을 갖기 때문에 소형 임베디드 시스템부터 대형 분산 시스템까지 많은 분야에서 사용되고 실시간 시스템을 기반으로 하는 실시간 프로그램도 많은 분야에서 사용되고 있다. 이러한 실시간 프로그램의 시간적 특성을 지키기 위해 개발자들은 프로그램 개발에 집중하지 못하고 실행시간의 정의와 정의한 실행시간의 정확성 검사에 많은 시간을 보내고 있다. 실시간 시스템에 대한 연구 결과로서 TMO 모델은 실시간 개념에 따른 시간 처리의 다양한 기능을 지원하고, 응답시간을 보장하여 개발자가 프로그램 개발에 집중할 수 있다. 하지만, 실행시간의 정의는 개발자에 의해 이루어지기 때문에 이를 정의하고 그 정확성 여부를 확인하는 작업은 어렵다. 이러한 문제로 인하여 실행시간 정의의 기준점을 제시할 수 있는 도구가 필요하지만 이를 위한 TMO 분석 도구에 대한 연구는 미흡하다. 이에 본 논문에서는 TMO 기반 정적 분석 도구를 위한 PS-Block을 제시한다. PS-Block은 블록 단위로 실행시간을 분석할 수 있는 기반으로써 프로그램을 작업 단위로 분리하여 분석할 수 있도록 한다. 이를 기반으로 실행시간을 분석하여 시간 정보 결정의 기준으로 하고, 실시간 메소드의 적시성 확인을 쉽게 함으로써 실시간/신뢰성의 향상과 개발 기간을 단축할 수 있다.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.1-9
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• 2015

Purpose: The objective of this study was to understand the operating mechanism of the rock-drill drifter, to explain how to setup an experimental test system and measure the strain of the drifter's rod, and to evaluate the drifter's performance with respect to the impact energy and blow frequency. Methods: The structure of the rock-drill drifter and its operating principle regarding the impact process were analyzed. Static calibration was carried out to calculate the correction factor using a drifter rod as the first step of the experimental test. The impact energy and blow frequency were then calculated based on strain measurements of the drifter's rod. Results: Experimental results showed that the tested drifter elicited a blow frequency of 3330 BPM (Blows Per Minute) and generated impact energy of 170 J/blow. This indicates that the drifter elicits a higher percussion speed and results in a lower impact energy compared to the hydraulic breaker at the same input power. Conclusions: The study proposed methodologies that deal with the experimental setup and the evaluation of the performance of the rock-drill drifter. These methodologies can be extensively used for validating and improving the percussion performance of the drilling equipment.

• Microbiology and Biotechnology Letters
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• v.1 no.1
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• pp.3-11
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• 1973

The biochemical characteristics of Astradix -P, isolated from Astragalus membranaceus Bunge as yeaststatic substance, were reported on a previous paper. And on this report, some relation to the nitrogen metabolism of yeast was studied. Inorganic or organic source of nitrogen easily uptaking yeast did not show any antagonistic action to the inhibitory action of Astradix -P on the yeast growth. Especially an organic nitrogen source, arginine, histidine and lysine, classified to basic amino acid, was reacted as an antagonistic substance to the sample. But, ornithine, a basic amino acid, did not show any antagonistic action to the sample. In the mixed media containing neutral and acidic amino acids as a nitrogen source, yeast growth was inhibited strongly. If the basic amino acid was added to the same mixed media, the yeast growth was not inhibited by Astradix-P therefore, the antagonistic action of basic amino acid to the Astradix-p was readily observed. The yeast static action of Astradix-P was partially related to the isoelectric point of amino acid as a nitrogen source. Yeast cells which propagated under the media containing growth inhibitor, Astradix -p, did not bring any remarkable denaturation of cell structure by electro-microscopic observation.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.919-925
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• 2016

In this study, multibody dynamic and mechanical analyses were conducted for the structure of roller chain bucket elevator system. The fatigue life of the roller chain elevator system was determined under static and fatigue loadings. Results of multibody dynamic analysis suggested that the maximum contact force occurred at the drive sprocket engagement point with the roller chain due to maximum tension. Fatigue analysis results suggest that the high load roller chain system is durable and safe because its life time is more than 700,000 cycles, close to its designed value (1,000,000 cycle). However, the contact portion of plate and pin needed a safety factor. The dynamic analysis of the heavy load roller chain was conducted with a multibody dynamic analysis program. The results obtained in this study can be utilized for dynamic analysis of roller chain systems in all industries.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.5
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• pp.399-406
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• 2014

Underwater acoustic materials are installed in order to reduce reflection, transmission and radiation of an underwater structure. The acoustic performance of the materials should be evaluated in accurately-controlled environment in terms of temperature and static pressure. In this paper, two pulse tubes, which are equipped with temperature and pressure controllers, are designed and developed to evaluate echo reduction(ER) and transmission loss(TL) of underwater acoustic materials. The procedures of the evaluation are suggested and the validation is carried out by comparing theoretical values to experimental results for a simple stainless steel specimen and free surface. In result, it is validated that developed pulse tubes are able to measure ER and TL with 2 dB tolerance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.8
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• pp.690-697
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• 2013

The magnets and vacuum chambers, which are the main facilities of the Pohang light source are installed on the storage-ring girders. System safety and reliability should be taken into account for the precise operating of the main facilities, so vibration analysis is essential to do this. Static and seismic analyses were performed for the design of structure considering safety, and also frequency and response spectrum analyses were performed for the precise alignment. With these results, the effects of surrounding vibration were checked. This paper explains about the design and vibration analysis of girder systems.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.7 s.172
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• pp.130-136
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• 2005

A new MR cylinder with built-in valves using MR fluid (MR valve) is suggested and fabricated fur fluid control systems. The MR fluid is a newly developed functional fluid whose obvious viscosity is controlled by the applied magnetic field intensity. The MR cylinder is composed of cylinder with small clearance and piston with electromagnet. The differential pressure is controlled by the applied magnetic field intensity. It has the characteristics of simple, compact and reliable structure. The size of MR cylinder and piston has $\varphi30mm\times300mm$ and $\varphi28.5mm\times120mm$ in face size, respectively and 0.8mm in gap length. Through experiments, it was found that the differential pressure is controlled by the applied magnetic field intensity under little influence of the flow rate, which corresponds to a pressure control valve. The differential pressure of 0.47MPa was obtained with the input current of 1.5A. The rising time was 2.3s in step response of a manipulator using the MR cylinder. The effectiveness of the MR cylinder was also demonstrated through the position control.