Mechanical Alloying에 의한 Ti_xCu_90-xAl_10(x=50,60)의 비정질화 및 열적성질

강종욱,김현구,김혜숙,이상열 조선대학교 기초과학연구소 1996 自然科學硏究 Vol.19 No.1

Amorphous powders of the Ti_xCu_(90-x)Al_10(x=50,60) system were synthesized by mechanical alloying method under an argon atmosphere. The amorphization process of the Ti_xCu_(90-x)Al_10(x=50,60) powders after milling by MA were studied by XRD, SEM and DSC experiments. We found that the best milling conditions of the Ti_xCu_(90-x)Al_10(x=50,60) powders were a ball-to powder weight ratio of 15 : 1 and a revolving velocity of 250rev min^-1 in this experiment. XRD patterns of the Ti_xCu_(90-x)Al_10(x=50,60) powders obtained by MA showed broad peaks as the increasing of milling times of the powders. So we confirmed the amorphization of the powders. The position of peak intensity 2θ(max.) of amorphous powders decreased nearly linearly with the increase of titanium concentration. Average particle size of the Ti_xCu_(90-x)Al_10(x=50,60) powders were 20∼26㎛ from SEM micrograph. In the DSC experiment, crystallization temperature and peak temperature were observed to increase for the Ti_xCu_(90-x)Al_10(x=50,60) powders with increased titanium concentration. The activation energy of the Ti_50Cu_40Al_10 and Ti_60Cu_30Al_10 powders were 260.57 and 253.10KJ/mole, respectively. the crystallization fraction of the Ti_50Cu_40Al_10 and Ti_60Cu_30Al_10 powders were found to be 3.02% at 458℃ and 1.32% at 477.2℃.

인도메타신의 투여가 치아 맹출 시 기질금속단백분해 효소의 분포에 미치는 영향

강윤구,남종현,이기수 대한치과교정학회 2006 대한치과교정학회지 Vol.36 No.2

이 연구는 치낭과 그 주위 조직 세포에서 matrix metalloproteinase (MMP)-3과 -9의 발현에 대한 인도메타신의 영향을 관찰하여 인도메타신이 치아의 맹출에 미치는 영향의 일단을 규명하기 위해 시행되었다. 생후 10-12주된 10마리의 개를 실험군 8마리와 대조군 2마리로 나누고 실험군은 인도메타신을 체중에 대하여 통상적 복용량인 인도메타신 2㎎/㎏/day을 7일간 및 14일간 투여한 군과 과량의 8㎎/㎏/day을 7일간 및 14일간 투여한 군으로 나누고 대조군은 빈 캅셀을 placebo로 투여한 후 희생하고 맹출 중인 영구치 치배를 적출하여 조직 처리하고 H-E 염색 및 MMP-3과 -9에 대한 면역염색 시행 후 광학현미경으로 검경하였다. 관찰결과 대조군에서는 파골세포, 조골세포, 치주인대 세포, 법랑모세포 및 상아모세포에서 모두 MMP-3과 -9의 발현이 뚜렷하게 관찰되었다. 대조군에 비해 인도메타신 투여군에서 파골세포, 조골세포, 치주인대 세포는 MMP-3과 -9의 발현이 억제된 소견이 관찰되었으며 인도메타신의 투여기간이 길수록 투여량이 많을수록 더 뚜렷하게 관찰되었다. 법랑모세포와 상아모세포는 대조군과 실험군의 MMP-3과 -9의 발현의 차이가 관찰되지 않았다. 이상의 결과에 의하면 prostaglandin (PG) 생합성 억제제인 인도메타신은 치낭의 파골세포, 조골세포 및 치주인대 세포에서 MMP-3과 -9의 발현을 억제하였으며 이는 인도메타신 투여로 치아 맹출이 억제될 수 있음을 시사한다. Tooth eruption requires remodeling of surrounding tissues. This study was aimed to investigate the effect of indomethacin on the dental follicle and paradental tissues during tooth eruption by observing the distribution and expression of MMP by the immunohistochemical method. Ten mongrel dogs of ten to twelve weeks old were divided into 5 groups: four experimental groups administered indomethacin 2㎎/㎏/day 8㎎/㎏/day and orally 2 times a day for 14 days and 7 days respectively, and the control group was administered a placebo. Permanent teeth before eruption and their surrounding tissues were selected and excised. H & E staining and immunohistochemical stainings of MMP-3 and -9 were performed and examined under the light microscope. Osteoclasts, osteoblasts, periodontal ligament cells, ameloblasts and odontoblasts of the control group all expressed MMP-3 and -9. In the experimental group, osteoclasts, osteoblasts and periodontal ligament cells showed reduced expression of MMP-3 and -9. Magnitude of MMP reduction in the experimental group showed a time and dose of indomethacin administration dependent manner. These results show that indomethacin inhibited MMP-3 and -9 expression in the dental follicle and surrounding tissues and suggest that when indomethacin is administered for long periods, tooth eruption could be delayed.

폴리올레핀계 폐플라스틱/복합filler 성형체의 난연성 및 기계적 물성 연구

강영구,송종혁 한국안전학회 2003 한국안전학회지 Vol.18 No.2

Flame retardancy and mechanical properties of recycled polyolefinic plastics/inorganic filler composite systems were investigated by using several inorganic flame retardants such as magnesium hydroxide and slag powder generated electro arc furnace. Compatibilizer used each maleic anhydride functionalized polyethylene (PE-g-MAH) and polypropylene(PP-g-MAH) or used mixture of these. The effect of polymeric compatibilizers on the properties of composites was studied by tensile and impact test, differential scanning calorimetry, morphology in the changed fracture mechanism. The improved adhesion was particularly reflected in the mechanical properties. The flame retardancy of composites was examined by measuring limiting oxygen index(LOI, ASTM D2863), smoke density(ASTM D2843) and vertical burning test(UL94). Regarding the flame retardant effect, the EAF slag powder is behaving as synergists as they are only active in the presence of magnesium hydroxide.

압력센서의 디지털 인터페이스와 신호처리에 관한 연구

강형구,이종호,안광희,이충호,박찬원 江原大學校 産業技術硏究所 1997 産業技術硏究 Vol.17 No.-

A smart pressure measurement system is described, which provides a precise A/D conversion and is highly suitable for communication with microprocessors. In order to avoid unstable problems of remote pressure sensing we have developed a new interface board which performs the A/D conversion and smart signal processing of the measured pressure data Serial communication software which is based on ASCII code commands is also developed to process initial setup an calibration functions as well as multi-drop communication with PC. The test and evaluation of the proposed system has been shown as having the better performance compared to the other types of existing pressure measuring systems and will give good applications to the industrial use where a highly precision remote sensing is needed.

폐플라스틱/제강 Dust 성형체의 용출안전성에 대한 연구

강영구,송종혁 한국안전학회 2003 한국안전학회지 Vol.18 No.4

In this study, We have investigated leaching characteristics of heavy metals for recycled plastic composites containing EAF(Electric Arc Furnace) dust & EAF slag. EAF dust & EAF slag used that is generated in the 3 steel-malting companies in domestic. The physical and chemical properties of EAF dust & slag was examined by measuring specific surface area, porosity, oil absorption test and chemical wetting analysis etc. Results of total analysis indicated that EAF dust, slag contained significant amount of hazardous metals such as Cu, Pb, Cd and Cr. But, In the leaching test of the recycled plastic composites containing EAF dust, slag by Korean Standard Leaching Procedure, composites shows much lower leaching concentration of heavy metals. It was concluded that the recycled plastic composites containing EAF dust, slag showed good physical and chemical characteristics. This means that the EAF dust, slag can be effectively used as a functional filler.

세라믹 종류에 따른 코어링 특성에 관한 연구

강용구,이태원,이종찬,최환 金烏工科大學校 産業技術開發硏究院 1999 産業技術開發硏究 Vol.15 No.-

A diamond core drill has been well carried out in the ceramics drilling. In this investigation, a vertical type machining center (MC) was used in the coring of Al₂O₃and Si₃N₄ceramics with a metal bonded diamond core drill. To clarify the mechanism of coring, the influences of coring conditions on the coring force, grinding ratio, succesive zone of coring were studied. At the wheel feed speed of 5.2 mm/min, and the wheel revolution of 3000rpm in Al₂O₃ceramics, the wheel speed of 2.7 mm/min, and the wheel revolution of 1500rpm in Si₃N₄ceramics, the best grinding ratio was obtained. But, from a viewpoint of coring speed, the wheel feed speed at 37 mm/min (Al₂O₃) and 10 mm/min (Si₃N₄) were best, when the coring depth was to 1 mm.

아·태지역에서 위성서비스 연구

강민구,임종태,차준섭 호남대학교 정보통신연구소 1995 정보통신연구 Vol.4 No.-

최근 급격히 성장하고 있는 아·태지역에서 위성통신과 방송의 진출방향의 모색을 위해 현재 서비스중인 위성통신과 방송시스템의 현황을 파악한다. 이를 바탕으로 하드웨어 측면은 이지역에서 위성중계기의 수요·공급을 분석하고, 소프트웨어 측면은 이들 지역에서 다자간 공동 위성방송을 위한 시장특성 조사 및 문화교류의 연수를 통해 위성분야에서 우리나라의 진출방안을 논한다. In this thesis, the satellite services in the asia-pacific area are analyzed for the co-operation and development of satellite communication. By the estimation of satellite transponder's need, the trend of satellite technology and the Koreasat planning is expected for the enhancement of our technical position in this area. Through the analysis of the asia-pacific cultural characteristics to satellite broadcasting, new securable strategies against the foreign unprotectable satellite culture and realizable approaches for co-work with asia pacific countries under the ApⅡ (Asia-Pacific Information Infrastructure) are proposed.

제강Slag 충진 폐플라스틱/복합 전도성 filler 복합재료의 전자파 차폐 효과

강영구,송종혁 한국안전학회 2004 한국안전학회지 Vol.19 No.4

Electromagnetic interference(EMI) shielding characteristics of composite filled with Cu flake and carbon brush powder as hybrid conductive filler and EAF slag have been studied. The coaxial transmission line method of ASTM D4935-99 was used to measure the EMI Shielding effectiveness of composites as formulation in frequency rage 100~1,000MHz. The SE also increases with the increase in filler loading. The hybrid filler filled composites show higher SE compared to that of only Cu flake. The correlation between SE and conductivity of the various composites is also discussed. The results indicate that the composites having higher filler loading(≥40wt.%) can be used for the purpose of safety materials to protect hazardous electromagnetic interference.

스포츠 活動時 스트레스의 適應過程에 關한 硏究

姜鍾求 全北大學校 1987 論文集 Vol.29 No.-

The purpose of this study is to find out the adaptation process of stress during sport activies, by comparing and analyzing the theories concerning with stress in sport activities. The results are as follows *Stress, which is inevitable to avoid, has psychologic, physiologic, and emotional causes; and simple and complex sport have different from of stress respectively. * In order to produce the process of adaptation to stress, compensation adaption made in the system of organism should keep a state of equilibrium. * In order that athletes produce excellent sport performnnce, they should adapt well to sport environment and psychological stress; and for this adaptation, athletes themselves should keep their stress in the optimum stress level and avoid any from of excessive stress. * In stress cases where the athlete shows what seems to be hyperactive, random, jittery behaviors, once again promoting contrasting actions may be helpfal. * Athletes need no train by practice, for adapting with stress, in the same manner that they train by practice for their event.

養液栽培商品의 生産과 流通實態 및 改善方向

姜宗求,梁承烈,梁元模 順天大學校 農業科學硏究所 1993 農業科學硏究 Vol.7 No.-

To illuminate the state and countermeasure of soilless cultural production and marketing in Korea, the survey of soilless cultural production through Agricultural Agent Center, questionnaire, field investigation, and literature analysis were performed. Soilless cultural farm-houses were 82 and area was 11.1 ㏊ on September, 1992. But its area of chief producing district and kind of crops are rapidly being changed. To solve the problems of soilless culture in Korea; old age and low education of farmers, small cultural area, financial difficulty, none standardization of facilities material and none specialization of varieties for soilless culture, it must be actively put in practice for soilless cultural improvement of Korea that the technical education strengthenning, financial support by government, standardization of facilities material and variety specialization. Poor sales network and policy, poor marketing intelligence network and activities, negligent selection and packing of products become the major cause of soilless culture's failure. Therefore, spontaneous sales network organization, marketing support of Horticultural Cooperative Association and Agricultural Cooperative Association, elevation of marketing intelligence power, and continuous effort of farmer for successful selection and packing of products are essential factors for soilless cultural development of Korea. Soilless culture is a royal road to change from primary agriculture to secondary agriculture for agricultural innovation, but there are many problems in this system and it is difficult to solve that problems by only farmer's effort. Therefore, not only farmer but also researcher, scholar, related groups and government concentrate their effort on solution of soilless cultural problems.