^(60)Co γ-선 조사에 따른 클로로프렌 고무의 열적 특성

김기엽,이청,류부형 한국안전학회 2003 한국안전학회지 Vol.18 No.4

The thermal properties of chloroprene rubber (CR) with ^(60)Co γ-ray irradiation has been investigated. The prepared CR was irradiated up to 1000kGy radiation dose by Co^(60) γ-ray and the radiation degradation of CR was investigated by thermogravimetric analysis and differential scanning calorimetry. Dynamic mechanical properties measurement and FT-1R observation are carried out as well. From these analyses results, the glass transition temperature(T_(g)), decomposition onset temperature(DOT), oxidative induction time(OIT), the peak temperature of loss modulus and mechanical tan δ values were compared for the radiation degradation level of CR. The tendency between T_(g) and peak temperature of loss modulus and mechanical tan a agreed well with radiation doses. Decomposition temperature, OIT and DOT showed the same tendencies as increasing radiation doses. It was verified that these analyses are available to estimate the degradation level of CR

맬라무드의 The Natural : 고통과성숙 Suffering and Moral Growth

나하엽,최기군 조선대학교 외국문화연구소 1997 外國文化硏究 Vol.20 No.1

Bernard Malamud was a humanist whose premise was pro-humanism and anti-nihilism. He was also a moralist who believed in the good within and perfectability of human beings. He was of the belief that suffering is unavoidable in this impersonal modern world, but that human beings can achieve moral or spiritual growth through learning from the suffering of the past. This paper aims to demonstrate that this belief of Malamud's is embodied in The Natural as in his other works. The hero of The Natural, Malamud's first novel, is Roy Hobbs who is an American pro-baseball player. Roy has superb potential, assisted by his magic bat 'Wonderboy', to become a real hero. However, he committed many mistakes because of his character flaws such as hubris, lack of tolerance, pursuit of lust instead of true love, and self-centeredness. Even after he experiences a lot of suffering in "Pre-game" because of his lust, he has not learned what he should have learned from his suffering. When he reappears in "Batter Up" after fifteen years' absence he repeats the same mistakes. His fatal mistake is that he agrees to throw the playoff game without considering his surrogate father figure Pop Fisher and his team with only a happy marriage life with Memo, a bitch goddess in the American Dream, in his mind. It represents his lust and egoism which is the biggest sin in Malamud's fiction. As a result he ends up being expelled from baseball forever and his almost unbreakable record being nullified. In this respect he is a failure, but he is not a complete one in that he sheds tears at the end of the novel in the regret that he has not learned from his suffering. This suggests he has attained some, if not full, moral growth. This study shows that the Natural is in accordance with Malamud's prevailing theme of moral growth through suffering although some critics comment on the novel otherwise.

Acrylonitrile Butadiene Rubber의 열적 열화 특성

김기엽,강현구,이청,류부형 한국안전학회 2003 한국안전학회지 Vol.18 No.4

Thermal degradation of Acrylonitrile butadiene rubber(NBR), which is used for 0-ring material as elastomeric sealed diaphragm valve in the nuclear power plants, is examined. The thermal degradation is accelerated at l30℃ by Arrhenius exploit method using the activation energy calculated by thennogravimetric analysis. The weight loss temperature and glass transition temperature are verified for thermally aged NBR The relationship between dynamic mechanical properties and elongation at break are also investigated. The threshold value of thermally aged NBR is a ten year in the change of elongation at break.

PID제어에 의한 單相 昇·降壓 整流器의 입력전류 특성에 관한 연구

徐基永,李壽欽,柳在葉,文相弼,李來一 경남대학교 신소재연구소 1999 論文集 Vol.11 No.-

Distortion Minimized of Input Current for Single-Phase Buck-Boost Rectifier is studied in the paper. To sinusoidal waveform the input current with a near-unity power factor over a wide variety of operating conditions, the output capacitor is operated with voltage reversibility for the supply by arranging the auxiliary diode and power switching device. Then the output voltage is superposed on the input voltage during on time duration of power switching devices in order to minimize the input current distortion caused by the small input voltage when changing the polarity. The tested setup, using two insulated-gate bipolar transistors(IGBT) and a microcomputer, is implemented and IGBT are switched with 20[kHz]. which is out of the audible band. Moreover a rigorous state-space analysis is introduced to predict the operation of the rectifier. The experimental and simulated results confirm that the input current can be sinusoidal waveform with a near-unity power factor and a satisfactory output voltage regulation can be achieved.

삽접법을 이용한 기계접목 메카니즘 연구

김주엽,이기명,박규식 慶北大學校農業科學技術硏究所 1997 慶北大農學誌 Vol.15 No.-

과채류의 재배에 있어서 접목은 작물의 안정적인 생산과 품질 향상을 위해 없어서는 안되는 기술이다. 그러나 지속적인 숙련 노동력의 감소와 농촌 인구 노령화 등으로 나타나는 노동력 부족 현상은 접목묘의 대량생산 공급에 어려움이 되고 있다. 본 연구에서는 기계접목에 있어서 접목법이 간단하며 접합부자재가 불필요한 삽접법을 이용하는 기계접목 메카니즘 개발의 기초연구를 수행하였다. 트레이상의 육묘상태에서 자동으로 접목하기 위한 기계접목의 기초연구로써 1본씩 수동 공급하는 반자동 기계삽접의 메카니즘 개발에 관한 연구로서 얻어진 결과를 요약하면 다음과 같다. 1. 접합부자재를 사용하지 않고 대부분 과채류에 적용가능한 삽접 기계접목장치의 메카니즘을 구성하였다. 2. 오이를 접수로 하고 신토좌와 흑종을 대목으로 하는 기계접목시험에서 모두 98%의 접목성공율을 나타냈다. 3. 1본 수동 공급에 의한 기계접목 시스템을 10초 정도로 접목 성능은 저조하지만 기계접목 메카니즘의 가능성을 확인하였다. Grafting is an important skill for the stable supply and production of high quality. However, the shortage of skillful labor has become great difficulty for a mass production of grafting-seedling. In this study, a suitable mechanism for a grafting machine was developed. The following summarize the results of this study: 1. An insertion method was selected for mechanism of the grafting machine without bonding agent, clip, pin. This insertion-grafting method can be applicable to general vegetables and a mass production system. In addition to, this method is suitable for developing the grafting mechanism. 2. Growing point was removed while remaining both cotyledons on rootstock. The productivity of this system was five fold greater than the one of an experienced labor. 3. The rootstock processing was placed on left and scion processing unit was placed on right of the system, then processed rootstock and scion graft by rotating 180˚. 4. The efficiency tests on mechanical grafting rate showed 98%.

Centipede Scolopendra subspinipes multilans L. Koch로부터 항균력이 있는 Centipedin의 추출, 정제 및 특성연구

김기태,최진성,민천홍,정일엽,박경배,조기승 한양대학교 이학기술연구소 1999 이학기술연구지 Vol.1 No.-

항균력이 있는 화합물인 Centipeding을 지네 Scolopendra subspinipes multilans L. Koch로부터 지용성 유기용매로 추출하였고, silicic acid column과 high S cation exchange chromatography 및 reverse-phase HPLC 등을 사용하여 고순도로 정제하였다. Gram-positive bacteria인 Staphylococcus aureus ATCC 6538P 및 gram-negative인 Klebsiella pneumoniae ATCC 8308 균주에 대하여 강한 항균력을 나타내었다. Dragendorff 시약에 의한 발색반응을 시행한 결과 Centipedin의 aromatic ring에는 nitrogen이 없음을 확이하였고 IR, Mass, NMR 분석 등에 의하여 Centipedin의 분자량은 162.1, 화학적 구조는 hydroxyl기와 carbonyl기를 함유하는 -hydroxyisocumarin으로 확인되었다. UV-spectrum 검색결과에 의하면 최대 흡수파장이 243 ㎚임을 확인하였고, melting point는 122℃이었으며, 실온에서 3개월간 방치된 Centipedin이 여전히 항균활성 및 화학적 구조를 유지하여 물리화학적 및 생물학적으로 안정한 화합물임으 알 수 있었다. The compound which has antibiotic activity was extracted and purified from centipede Scolopendra subspinipes multilans L. Koch by diethyl ether, silicic acid column and high S cation exchange chromatography followed by reverse-phase HPLC. This compoung named "Centipedin" showed antibiotic activity aganist microorganisms such as Gram^(+) -bacteria Staphylococcus aureus ATCC 6538P and Gram^(-) -bacteria Klebsiella pneumoniae ATCC 8308. Dragendorff test showed that there is no aromatic nitrogen within the Centipedim. The molecular weight of the Centipedin was 162.1 daltons as determined by mass spectrometry. The instrumental analysis of IR and NMR techniques revealed the molecular structure of Centipedim as 8-hydroxyisocoumarin. The UV-spectrum of Centipedin showed maximum absorption at 243 ㎚, and melting point was 122℃. Centipedin was stable at room temperature for three months in appropriate buffers.

자가골 이식과 골유착상 임프란트를 이용한 하악골 개선

전주홍,박기광,조경엽,이상대,송정록 충남대학교 의과대학 지역사회의학연구소 1995 충남의대잡지 Vol.22 No.1

Bony defects of mandible caused by trauma, infection, or tumor resection have been reconstructed by autologous bone graftings. These reconstruction can restore facial contour and integrity of the oral cavity. However, it is often necessary to reduce the bulk of bone to allow soft tissue coverage of the graft. Therefore, the construction of removable dentures in this situation is fraught with frustation. The use of osseointegrated implants is a method to allow improved anchorage and support for the successful fabrication of dental protheses. We report two cases of the use of osseointegrated implants of the Branemark type(3i), in conjunction with bone grafting to the lower jaw.

레트로바이러스의 표면단백질 : 인슐린의존형 당뇨병의 동물모델인 NOD 쥐의 혈청과 반응하는 새로운 자가항원 A New Autoantigen Reactive with Non Obese Diabetic (NOD) Mice Sera

김경수,김기환,김현만,윤지원,강엽 아주대학교 1997 아주의학 Vol.2 No.2

IDDM (Insulin dependent diabetes mellitus) is believed to be an autoimmune disease and characterized by the immune activation against insulin-producing pancreatic beta cell. The identification and characterization of new autoantigens reactive with an activated immune System would heip to elucidate the pathogenic mechanism of this disease. Several autoantigens are trying to apply for diagnosis and prevention of IDDM. The NOD (non obese diabetic) mice have been the best model for studying the pathogenesis of human IDDM. To identify new autoantigens reactive with activated humoral immunity of NOD mice, the lambda gt11 cDNA library was constructed from NOD-derived pancreatic beta cell (MIN6N8a: mouse insulinoma cell) and screened with prediabetic NOD sera. Mine positive dones were selected from 2x10^(5) phage plaques. The 5'-end sequencing and homology searching showed that six clones from nine clones had over 98% sequence homolgy with the retroviral envelope gene. Full sequendng reveated that the cloned gene was a fragment of ecotropic retrovirus (emv-3) envelope gene. To confirm the immunoreactivity of doned retroviral envelope protein, the cloned gene fragment was expressed in an E.coli expression vector System. Western blotting showed that the recombinant envelope protein fragment also reacted with prediabetic NOD sera.

CSPE의 난연,기계 및 전기적 특성에 미치는 무기질 첨가제의 효과

류부형,김기엽 동국대학교 경주대학 1999 東國論集 Vol.18 No.-

In this paper, were investigated the inorganic fire retardant additives on chlorosulfonated polyethylene(CSPE) in order to improved the fire retardant characteristics of CSPE. Therefore, fire retardant characteristics such as limited oxygen index(LOI) and decomposition onset temperature(DOT), mechanical elongation and tensile properties, and electrical properties on each CSPE contained with fixed concentration of 5 types fire retardant additives and virgin CSPE sample were measured. CSPE contained with inorganic additives which is PbO, Sb_2O_3, Al(OH)_3 and Mg(OH)_2 were improved fire retardant characteristics rather than virgin CSPE, but seems to be declined mechanical and electrical properties on the whole samples. From the integrated results, concludes that the most excellent inorganic fire retardant additive is Sb_2O_3.

TGA를 이용한 가교폴리에틸렌의 방사선 열화 평가

이청,김기엽,류부형,임기조 한국안전학회 2003 한국안전학회지 Vol.18 No.2

Radiation degradation of crosslinked polyethylene(XLPE) was investigated using thermogravimetric analysis (TGA), The results of TGA were compared with FT-IR, melting temperature, oxidation induction time, and elongation al break on the XLPE exposed by γ-ray. 5% decomposition temperature of γ-ray irradiated XLPE showed similar tendencies with the case of elongation at break. Both properties agreed below 1000 kGy, however, did not show any remarkable characteristics above 1000 kGy, these properties can be useful to evaluate the radiation degradation of XLPE for only low irradiated region. Above 1000 kGy, the thermal decomposition activation energy showed decreased, on the contrary, increasing below 1000 kGy. Compared with FT-IR spectrum of irradiated XLPE, it was confirmed that the oxidation reaction was still occurring below 1000 kGy. Radiation degradation of XLPE was dependent upon the irradiation doses, TGA can be a useful tool to evaluate the degradation.