방사선조사가 Porphyromonas gingivalis에 미치는 영향

이창환,김규태,최용석,황의환 대한구강악안면방사선학회 2008 Imaging Science in Dentistry Vol.38 No.1

Purpose : The aim of this study was to observe a direct effect of irradiation on the periodontopathic Porphyromonas gingivalis (P. gingivalis). Materials and Methods : P. gingivalis 2561 was exposed to irradiation with a single absorbed dose of 10, 20, 30, and 40 Gy. Changes in viability and antibiotic sensitivity, morphology, transcription, and protein profile of the bacterium after irradiation were examined by pour plating method, disc diffusion method, transmission electron microscopy, RT-PCR, and immunoblot, respectively. Results : Viability of irradiated P. gingivalis drastically reduced as irradiation dose was increased. Irradiated P. gingivalis was found to have become more sensitive to antibiotics as radiation dose was increased. With observation under the transmission electron microscope, the number of morphologically abnormal cells was increased with increasing of irradiation dose. In RT-PCR, decrease in the expression of fimA and sod was observed in irradiated P. gingivalis. In immunoblot, change of profile in irradiated P. gingivalis was found in a number of proteins including 43-kDa fimbrillin. Conclusion : These results suggest that irradiation may affect the cell integrity of P. gingivalis, which is manifested by the change in cell morphology and antibiotic sensitivity, affecting viability of the bacterium.

UV/TiO_(2) 수처리 공정에서의 살균에 관한 연구

이규환,이상진,이용재,이동석 강원대학교 산업기술연구소 2007 産業技術硏究 Vol.27 No.A

This study investigated disinfection effect by general water purifier and water purifier with UV light disinfection. The results are as follows : (ⅰ) The general bacteria existed plentifully in a storage tank before treatment (ⅱ) Water treated in water purifier did not meet the water treatment regulation standard since the presence of bacteria, whereas with UV light application the regulation standard is totally satisfied. (ⅲ) Photocatalytic disinfection process with UV light in the presence of TiO_(2) more effectively killed general bacteria than UV light only.

대칭형 접합이음 보강판의 피로균열성장거동

이환우,강선규 慶南大學校 附設 工業技術硏究所 1999 硏究論文集 Vol.17 No.-

보강판은 항공기 구조물의 대부분을 점유하고 있으며, 현실적으로 매우 중요한 균열문제중의 하나이다. 본 연구에서는 복합재료 보강재가 접합된 보강판의 응력확대계수와 피로균열성장거동을 실험ㆍ평가하였으며 그결과를 균열성장과 피로수명의 관계로 정리하여 보강판의 형상비 조건과 보강재의 재질 및 강성비의 영향등을 비교 ㆍ고찰하였다. The stiffened panel is representative of a large portion of aircraft construction and therefore has much practical importance. In this paper, the influence of various shape parameters on the stress intensity factors and the fatigue crack growth in the panels with bonded composite stiffeners are studied experimentally. Results are presented as Crack Growth Rates for various values of crack lengths, stiffening ratios, and stiffening Materials.

교육대학의 교수방법개선에 관한 연구

김규환,최현섭,김용식,허숙 仁川敎育大學校 1993 論文集 Vol.27 No.2

Current Conveyor를 이용한 2차 대역통과 SCF의 실현

金圭煥 군산대학교 1991 群山水産專門大學 硏究報告 Vol.25 No.2

The most SCF has been built complex circuits having many resistors, capacitors and switches. There are problems to reduce the cost and the number of elements, also to make the integrated circuits easily. In this paper, a design method of 2nd Band Pass SC Filter using only one C.C. built by MOSFET and four capacitors are presented. The characteristics of circuits could be possible to connect circuits without subordinative buffer according to input high impedance of the circuit. And integrated circuit could be made simply and easily because Q of the circuit is decided by ratio of circuit elements. Also, it shows that frequency characteristics of designed SCF by experiment were almost similar to the of theoretical values.

유통정보시스템의 효율적 구축방안에 관한 연구 : 부산·대구지역을 중심으로 Focusing on the Sales Business in Pusan-Taegu

李奎煥,朴善泰,金香蘭 대구산업정보대학 1998 논문집 Vol.12 No.1

This study aimed first to correctly understand informationalization of distribution, that is POS System, EDI, EOS, and distributing VAN, second to observe the present condition and preceeding examples of construction of informationalization of distribution in our country and to execute analysis of corroborative evidence regarding informationalization of distribution centered on distributing companies in Pusan and Taegu districts, third to grasp the impeding primary factors when informationalization is built up, and fourth to present effective building up lans of informationalization of distribution in Pusan and Taegu districts which will be the foundation of informationalization of distribution in the distributing business circles. The writer studied, for the method of study, by dividing into theoretical study, research portion of the present condition and preceeding examples of building up informationalization of distribution, and analysis of corroborative evidence. For the theoretical study portion and analysis examples, the study method by documentary records was applied, and domestic and foreign books, theses and periodicals related to the informationalization of distribution were consulted. For the analysis of corroborative evidence, the writer studied by questionaires regarding opening of distributing markets, distriubuting environment and distributing information system of the distributing market by the retail dealers as its objects, and selected research by questionaires to collect information by personally visiting each company. About 15 universities and junior colleges related to the distributing industry in our country produce about 1,280 of fundamental manpower related to distrribution every year, and a portion of large-sized distributing companies established and are managing even inter-company colleges, but it is the real situation that these are not sufficient in quality and quantity. In order to cultivate manpower specialized in distribution, the industry, universities and government, forming a trinity, should cope with the matter jointly, and especially, the government level should newly establish subjects of study related to the distribution drastically and political and financial support should be necessarily followed. Also, if POS system is induced, as the source of tax revenue is completely exposed, compared with those companies which do not induce POS System, they will suffer disadvantage, so preferential treating method is necessary in case of application of valued added tax or income standard. The customary practice of dealing without data harmful to normal commercial transaction order and against equity is pointed out as the most fundamental problem point being held by the distributing business circle in our country. For the sake of effective building up the distributing information system, the source making rate shall be raised, the ratio of domestic made instruments of POS System shall be increased, by developing EOS System which can be connected with manufacturing companies, POS System shall be utilized effectively by connecting with the management information system of the whole enterprises, EIS (Executive Information System) and various data base, and shall be connected with EOS with other components of distributing channel and EOS and EFT (Electronic Fund Transfer) system shall be connected through EDI or VAN. Such distributing information system can accomplish composite distribution information systematization, so it can promote greatly the management power not only of distributing business but manufacturing business.

난분해성 유기물질 제거를 위한 오존/촉매 공정의 비교에 관한 연구

이규환,이유미,이동석 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.A

Ozone alone and catalytic ozone processes were introduced for treatment of humic acid, which is representative refractory organic compound. The treatment efficiencies of humic acid in each process were analyzed in pH variation, DOC removal, and UV_(254) decrease. Mn loaded GAC catalyst was prepared by loading potassium permanganate onto the granular activated carbon surface. BCM-GAC and BCM-Silica gel catalyst were prepared by BCM. UV_(254) decrease in all processes was comparatively high with efficiency over 87%. DOC removal in ozone/GAC process was the highest with 78%, and removal rates for other processes followed the order ozone/BCM-GAC(62%) > ozone/BCM-silica gel(45%) > ozone/silica gel(43%) > ozone/Mn Loaded GAC(42%) > ozone alone(37%).

금속이온 치환법으로 제조된 티타니아를 이용한 유기물 분해에 대한 연구

이규환,이동석 江原大學校 産業技術硏究所 2008 産業技術硏究 Vol.28 No.A

In recent years, much attention has been paid to "Photocatalytic oxidation" as an alternative technique, where the pollutants are degraded by UV-irradiation in the presence of a semiconductor suspension such as titanium dioxide. TiO_(2) is the most often used photocatalyst due to its considerable photocatalytic activity, high stability, non-environmental impact and low cost. In this research, the photocatalytic degradation of humic acid, acetaldehyde and methylene blue in UV/TiO_(2) systems has been stydied. The effect of calcination temperature for manufacturing of TiO_(2) Photocatalysts and type of photocatalysts on photodegradation has been investigated. Photocatalysts with various metal ions(Mn, Fe, Cu and Pt) loading are tested to evaluate the effects of metal ions impurities on photodegradation. The photodegradation efficiency with Pt-TiO_(2) or Fe-TiO_(2) or Cu-TiO_(2) is higher than Degussa P-25 powder. However, the photodegradation efficiency with Mn-TiO_(2) is lower than Degussa P-25 powder. The photocatalytic properties of the nanocrystals were strongly dependent upon the crystallinity , Particle size, standard reduction potential of various transition metal and electronegativity of various transition metal. As a result photocatalysts with various metal ion loading evaluated the effect of photodegradation.

저감도 6차 대역통과 SCF의 실현

김규환 群山大學校 情報通信技術硏究所 1998 情報通信技術硏究論文集 Vol.2 No.-

Recently, the demand of Band Pass SC Filter has been increased as the circuits of currents communication system. But as the most SCF has been built in the complex circuits having many resistors, capacitor and switches. There are problems to reduce the cost and the number of elements, also to realize low-sensitivity. In this paper, in order to design simple and economic 6th order Band Pass SC Filter using the SC integrators of operational amplifiers, all the inductances in the 6the LC Band Pass Filter network were replaced by switched-capacitor. And, SC BPF were studied analystically and its characteristics were considered. Also, their results show that the sensitivity and frequency characteristics of designed SC BPF were almost similar to that of the theoretical and experimental values.

Trarsistor의 신뢰성에 관한 고찰

김규환 군산대학교 1974 群山水産專門大學 硏究報告 Vol.8 No.2

The Transistor Reliability affects the Length of Life and Cost of Communication Equipement. In this paper, I wrote about the Reliability of Transisto used in the Microwave Multiplex Carrier Equipemens & Carrier Telephone Equipement during two years. It is defined as the Probability that indicates th eability of Transistor used under various conditions. As a result, The reliability of Transistor may be expressed by Failure Rate. On the ground of Observation of the Characteristic Variation, the Failure Rateand the Failure Cause, Its result was follows. 1) The Failure Rate of transistor by external point of view is showed more than internal. therefore, so as to reduce failure rate, It must be end-owed with the sufficient condition within the Area of Safe Operation of Transistor. 2) In case of the normal operating, the failure rate is approximately 0.002-0.1(%/1000hr), Moreover, the failure rate of transistor used , in electron computor and electron switch board must be reqired about 0.0001(%/1000hr). Finally, the oneopf the best methods which we can improve the reliability of transistor is the developement of the technique about the choicement of good transistor.