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Improvement of Thermoplastic Forming Ability of Ti–Zr–Ni–Cu Metallic Glass by Addition of Sn
Yeong‑Seong Kim,Woo‑Chul Kim,Won‑Tae Kim,Do‑Hyang Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6
Ti–Zr–Ni–Cu metallic glass attracts an attention as a precursor of superelastic alloy that can be deformed into nm scalecomplex shapes. However, since the thermal stability of Ti–Zr–Ni–Cu metallic glass in the supercooled liquid region is quitelow, application of thermoplastic forming is limited. Therefore, in the present study, the effect of Sn addition on thermoplasticforming ability of Ti–Zr–Ni–Cu metallic glass has been investigated. Sn containing (Ti35Zr15Ni35Cu15)99Sn1 metallic glassexhibits longer incubation time before onset of crystallization than Ti35Zr15Ni35Cu15metallic glass, resulting in significantimprovement of thermoplastic forming ability. The crystallization behavior changes from three-dimensional growth of saturatednuclei to three-dimensional growth with constant nucleation rate with the addition of Sn. The overall activation energyfor crystallization of (Ti35Zr15Ni35Cu15)99Sn1 metallic glass is higher than that of Ti35Zr15Ni35Cu15metallic glass, indicatingthat the thermal stability of metallic glass is improved by addition of Sn. Because nuclei are continuously generated duringthe crystallization in (Ti35Zr15Ni35Cu15)99Sn1, the average grain size is much smaller than that in Ti35Zr15Ni35Cu15.
김우성,이선화,김상엽,정동윤,김재이,이영자,이홍재,정성욱,박흥재 한국환경과학회 2003 한국환경과학회지 Vol.12 No.10
Pesticides were extracted from samples with 70% acetone and methylene chloride in order, and then cleaned up via open-column chromatography apparatus packed with fiorisil, and finally analyzed simultaneously the organophosphorus pesticides using GC/NPD, Ultra-2 and Ultra-1 fused silica capillary columns were used to separate and identify the products. Recovery of most analytes from soybean sample, taken from pesticide residues well, was greater than(80%) for all except(6) analytes. This method can simultaneously determine multiple pesticides with a high degree of accuracy and precision.
GC-ECD를 이용한 유기염소계 및 Pyrethroid계 농약 동시 분석법
김우성,이선화,김재이,정지윤,이명자,박영채,이영자,정성욱,이봉헌,박흥재 한국환경과학회 2003 한국환경과학회지 Vol.12 No.4
Pesticides were extracted from samples with 70% acetone and methylene chloride in order, and then cleaned up via open-column chromatography apparatus packed with florisil, and finally analyzed simultaneously the organochlorine and pyrethroid pesticides using GC(ECD). An ultra-2 fused silica capillary column was used to separate and identify the products. The resolution between the last isomeric peak of cypermethrin(59.987min) and the first isomeric peak of flucythrinate(60.043min) was not satisfactory. The last isomeric peak of fenvalerate(62.344min) and the first isomeric peak of fluvalinate(62.397min) were overlapped. Recoveries of soybean sample for the most pesticides were 73.3% to 102.4%. Detection limits were between 0.004 and 0.063 ㎍/㎎ when this method was used.
8년간(1992~1999) 산업안전보건연구원에 의뢰된 직업병 심의 사례 분석
강성규,김규상,김양호,최정근,안연순,진영우,최병순,양정선,김은아,채창호,최용휴,김대성,박정선,정호근 대한산업의학회 2000 대한직업환경의학회지 Vol.12 No.2
Objectives : Pneumoconisis and noise-induced hearing loss (NIHL) have been reported as main occupational diseases by the Special Health Examination. The Industrial Accident Compensation Insurance has reported various work-related diseases, however, these two diseases occupied almost a half of compensated cases. Therefore, it was not well known about the status of occupational diseases other than pneumoconiosis, NIHL, and cardio-cerebrovascular accident (CVA). This study was conducted to analyze claimed cases as an occupational disease, that was requested to the Korea Industrial Safety and Health Agency (KOSHA). Methods : The local office of the Korea Labor Welfare Corporation (KLWC) has asked the KOSHA for confirmation of claimed cases as an occupational disease. We analyzed 379 cases requested from KLWC, the Ministry of Labor, employers, unions and occupational health agencies from 1992 to 1999. Results : Male was 80.7 % of the requested cases. Their mean age was 42 years old and 75.5 % of them were more than 35 years old. The requested cases were increased rapidly from 25 cases in 1992 to 108 cases in 1999 and the accept rate was 50.7 %. The majority of requested cases were respiratory diseases(22.4%), cancers(18.5%), Neuropsychiatric problems(14.5%), and musculoskeletal problems(13.5%). The accept rate was high in reproductive, respiratory, musculoskeletal and digestive disorders and low in neuropsychiatric, renal and otologic problems and occupational cancers. 73.6% of them were caused by chemical agents, especially 28.5 % were by organic solvents. 67% of them were clinically confirmed at university hospitals. A half of the cases were from KyongIn area, even the request came from the whole country. Conclusions : A claim was common in workers whose age was over 35 years old and exposure history was over 10 years. The respiratory diseases and neuropsychiatric disorders were still main problems in occupational health and occupational cancers was increasing even though its accept rate was not high yet.
고정 흡착층에서 벤젠과 톨루엔의 단일 및 이성분 흡착특성
김한수,박영성 대전대학교 환경문제연구소 2001 환경문제연구소 논문집 Vol.5 No.-
The effects of various parameters, such as adsorption temperature, interstital velocity, concentration of adsorbates and sapect ratios(L/D) of the fixed bed, on the adsorption characteristics referring to single and binary component were studied in a fixed bed of an activated carbon. For the single component, the break point decreased with increasing the adsorption temperature, interstitial velocity and concentration of adsorbates. Interstitial velocity, concentration of adsorbates and adsorption temperature had considerable influence upon the MTZ and LUB that obtained through the breakthrough curves. An adsorption isotherm of benzene and toluene was determined with single component, Langmuir, Freundlich and Langmuir-Freundlich isotherm agreed with experimental data fairly well. For the binary component, the adsorption breakthrough curve of key component(toluene) was sigmoidal as in the case of the single component system. However, the breakthrough curve of non-key component(benzene) was entirely different from that of the single component adsorption process. The mageitude of roll up increased with increasing concentration of adsorbates and aspect ratio of the fixed bed, and decreased with increasing interstitial velocity.
김윤영,문성익,허광삼,양두영 제주대학교 산업기술연구소 2000 尖端技術硏究所論文集 Vol.11 No.1
In this paper, A down converter to convert RF signal into IF signal is designed at the WLL base-station. It consists of low noise amplifier module and down mixer module. The low noise amplifier module is composed of three-stage and a feedback circuit is added in the first-stage low noise amplifier in order to obtain unconditional stability and good flatness. The configuration of the down mixer module is a single-ended type gate mixer. For the good isolation characteristic of each port, a bandpass filter and a lowpass filter are inserted in the input and output port. To design the down converter without the IF power amplifier, it is important to maximize conversion gain. So the down converter of this paper is designed for the purpose of obtaining a high conversion gain. From the results, the IF output power is -12.68dBm when the LO and the RF power level are 7dBm and -80dBm, respectively. Also when the LO power level is 7dBm, P1dB is -0.19dBm, and the RF input power range shows 70dB on wide operating range.
활성탄을 이용한 휘발성 유기화합물(VOCs-BTX)의 흡착특성
김한수,장효섭,박영성 大田大學校 環境問題硏究所 1998 환경문제연구소 논문집 Vol.3 No.-
Adsorption characteristics of volatile organic compounds(VOC) by activated carbon were investigated using a continuous generation system for VOC. As samples of VOC, benzene, toluene, and xylene were adopted. The pelletized activated carbon prepared by Hanil Green Tech. Company was used as a adsorbent. As operating variables, adsorption temperature(25∼45℃) and partial pressure of VOC(0.25∼22.5mmHg) were applied. Adsorption characteristics such as adsorption rate, adsorption equilibrium capacity, and breakthrough curve were studied. The experimental results show that the adsorption rate increases with increasing temperature and partial pressure. Also, the adsorption equilibrium capacity increases with increasing pressure. and decreases with increasing temperature.
유전체로 둘러싸인 속빈 직육면체 도파관을 사용한 레이저 공진기에서 횡특성모드의 왕복손실
金允溟,金永植,李鍾旿,徐七成,박재우 단국대학교 1989 論文集 Vol.23 No.-
The round-trip losses of CO_2 laser wavelength in a hollow rectangular dielectric waveguide with external spherical mirrors are calculated. The propagative attenuations of some higher order modes with different polarization are analyzed as well as EH_11 fundamental mode. Computations of the losses in coupling radiation of various modes from the guide into free space and back into the guide, as a function of mirror curvature and position, are also presented. The overall return losses of various modes are the sum of the two kinds of losses.