Co^60-γ선을 조사한 p-MOS Capacitor의 전기전도 특성

류부형 동국대학교 경주대학 1995 東國論集 Vol.14 No.-

In this study, the DC electrical conduction characteristics(I-V_g) on the p-MOS capacitors irradiated under Co^60-γ ray were investigated. The I-V_g characteristics are strongly influenced by total doses on the irradiated p-MOS capactiors. When forward bias(-V_g) was applied to the p-MOS capacitors, the conduction current through the oxide(SiO_2) layer are the ohmic current on the low field range and the space charge limited current(SCLC) on the high field range. The ohmic curent is increased and the transition voltage from ohmic current to SCLC is shifted toward a higher voltage with the irradiated doses to be increased. These tendency can be exlained that the effective field on SiO_2 layer was increased under forward bias according to the positive space charges were induced in SiO_2 by γ-ray irradiation. When reverse bias(+V_g) was applied to the samples, the conduction current through the SiO_2 layer are the ohmic current on the low field range and the Schottky current on the high field range. The ohmic current is decreased and the transition voltage from ohmic current to Schottky current is shifted toward a lower voltage with the irradiated doses to be increased. It is suggested that the height of effective barrier on SiO_2/Si interface and the effective field on SiO_2 layer was decreased under forward bias, because the positive interface trap charges were induced on SiO_2 by γ-ray.

Co^60-r선 조사에 따른 이축연신 폴리프로필렌 필름의 열자격전류 특성 변화

류부형,김민,김규백 동국대학교 경주대학 1997 東國論集 Vol.16 No.1

In order to investigate the Co^60-γ ray irradiation effects on the thermally stimulated current(TSC) characteristics of the biaxially-oriented polypropylene (BOPP) films, TSCs on the 15㎛ thick BOPP films before and after irradiation were observed in the temterature range of -120∼120℃ and at the forming electric field of 10, 30 and 60MV/m. Two distinguished peeaks such as β peak and α peak, the former was regarded as the depolarization process of dipoles on a amorphous region and the latter was attributed the thermally excited detrapping process of the trapped ions on a crystaline region in BOPP, were observed in the TSC spectra. From the observed results, the physical properties of γ-ray irradiated BOPP that are activation energy and relaxation time of charged particles, moment of dipole and forming field dependencies on TSC characteristics were analyzed and discussed.

베이즈 방법을 이용한 신규 원자력발전소 EDG신뢰도의 추정에 관한 연구

류부형,심규박 동국대학교 경주대학 1997 東國論集 Vol.16 No.1

A commercial nuclear power plant contains at least two emergency diesel generaters(EDG) to control the risk of severe core demage during the station blackout accidents. Therefore the reliability of the EDG's to start and load-run on demend must be maintained at a sufficiently high level. Until now, Wyckoff estimators, a simple start and load-run successful rates, were used to calculate the EDG's reliability. however, this method has been many defects in various points at a situation has not enough the operation data of EDG/ In recent, K.B. Shim et al.(1996) was proposed that Bayes estimator method is more reasonable our situation. In this paper, we will apply Wyckoff method and Bayes method to estimate the reliability of EDG at construction stage and show Bayes method are more reasonable in our situation with various sides.

이축연신폴리프로필렌 필름의 Co^(60)-γ선 조사에 따른 전기전도 특성 변화

류부형,우흥식 동국대학교 경주대학 1996 東國論集 Vol.15 No.-

In order to investigate the CO60-γray irradiation effects on DC electrical conduction characteristics of the biaxially-oriented polypropylene(OPP) films, DC current on the 15㎛ thick OPP films before and after irradiation were observed in the temterature range of 25~55℃ and in the electric field of 10 ~250MV/m. The electrical conduction characteristics of OPP films were devided into the four regions having different mechanisms as the hopping, space charge limiting, Schottky emission and Fowler-Nordheim's tunneling effects with the increase of the electric field. The conduction current through the OPP film were concluded as the ohmic current on the fields below 55MV/m, the space charge limited current(SCLC) on the field range from 55 to 90MV/m, the Schottky current on the mid fields from 90 to 175MV/m and the tunneling current on the high fields above 175MV/m. The conduction current on the all regions increases in proportion to the increase of the irradiated dose and temperature, but the transition points from ohmic current to SCLC and from Schottky current to tunneling current are shifted towared a lower field as the irradiated dose and temperature increase. The crystallinity of OPP film increased with increase of the irradiated dose, which caused the boundary fields of conduction regions to shift toward a higher fields.

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.

Fermentation Conditions for the Production of Cell Mass in Streptococcus faecalis and Endospores in Bacillus mesentericus

현형환,김부연,류한봉 한국외국어대학교 외국학종합연구센터 부설 기초과학연구소 1996 기초과학연구 Vol.4 No.-

Streptococcus faecalis는 glucose, lactose등을 탄소원으로 잘 이용하였으며 glucose를 탄소원으로, yeast extract와 casitone을 질소원으로 구성된 배지를 사용하여 pH 7.0에서 control되는 fermentor 배양에서 optical density(660nm) 7.3(viable cell concentration 6.5×10(9) cells/㎖)이상의 높은 cell concentration을 얻을 수 있었다. Bacillus mesentericus의 sporulation을 최대화 하기 위한 발효 조건을 조사한 결과 glucose를 위한 최적 CaCl₂농도는 0.lmM이었다. Streptococcus faecalis rapidly fermented glucose and lactose as a C-source, and the maximum cell concentration was obtained when grown in a jar fermentor that contained YCG medium consisting of glucose as a C-source and casitone and yeast extracts as a N-source, and that was controlled at pH 7.0. From experiments to maximize the sporulation efficiency in Bacillus mesentericus, glucose caused the decrease in sporulation efficiency, and calcium chloride was stimulatory for sporulation, of which optimum concentration was 0.lmM.

방사선그라프트 중합법에 의한 금속이온의 회수

김민,류부영 동국대학교 경주대학 1997 東國論集 Vol.16 No.1

The kinds of functional groups, chelate forming group(iminodiacetate: IDA) and ion-exchange (sulfonic acid: SS) group, were introduced into a microfiltration hollow fiber membrane by radiation-induced grafting and subsequent chemical modification. The conversion of the epoxide into the functional group was investigated as a function of the degree of GMA grafting. The densities of the SS-T and IDA-T fiber were 1.8 m㏖/g and 2.2m㏖/g, respectively. The pure water flux through the SS-T fiber decreased sharply when the conversion was btween 30 and 40%, while that through the IDA-T fiber had not been changed much. The higher conversion of the epoxide into the ion-exchange group caused the swelling of the polymer chain grafted onto the pore interface and caused the decrease of the water permeability through the hollow-fiber membrane. Th effect of the capacity of metal ion to SS-T and IDA-T fiber was investigated. The SS-T fiber was superior to the IDA-T fiber with regard to the adsorption capacity of metal ion.

비상디젤발전기의 信賴度 推定方法에 관한 연구

심규박,류부형 동국대학교 경주대학 1996 東國論集 Vol.15 No.-

A commercial nuclear power station contains at least two emergency diesel generates (EDG) to control the risk of severe core damage during the station blackout accidents. Therefore the reliability of the EDG's to start and load-run on demand must be maintained at a sufficiently high level. Until now, a simple start and load-run success rates was used to calculate the EDG's reliability. However, this method has been many dafects. Recently, the work of Martz (1996) proposed a parametric emprical Bayes (PEB) estimator to find the EDG' s reliability. For binomial sampling model with pass/fail data and a beta prior distribution, PEB point and credibility interval estimates are provided for the EDG's reliability. In this paper, we will compare above two methods and show Martz's method is more reasonable in our situation with several examples.

Polyvinylidene fluoride의 ^(60)Co 감마선 조사에 의한 구조 변화

이청,김기엽,류부형 한국안전학회 2004 한국안전학회지 Vol.19 No.3

The radiation-induced changes taking place in poly(vinylidene fluoride) (PVDF) exposed to ^(60)Co γ-ray irradiation were investigated in correlation with the applied doses. Samples were irradiated in air at room temperature by ^(60)Co γ-ray to doses in the range of 200 to 1000kGy. Various properties of the irradiated PVDF were studied using MF, differential scanning calorimetry (DSC), gel fraction and elongation. ^(60)Co γ-ray irradiation was found to induce changes in chemical, thermal, mechanical and structural properties of PVDF and such changes vary depending on the radiation dose.

^(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