Effect of polydopamine‑modified reduced graphene oxides on the catalytic activity of Pt nanoparticles catalysts for fuel cell electrodes

Joo‑Hyoeng Woo,Soo‑Jin Park,Sungwook Chung,Seok Kim 한국탄소학회 2019 Carbon Letters Vol.29 No.1

We have studied a method to prepare polydopamine-modified reduced graphene oxide-supported Pt nanoparticles (Pt– PDA–RGO). The Pt–PDA–RGO nanocomposites were synthesized by a wet-coating process, which was induced by selfpolymerization of dopamine. As an eco-friendly and versatile adhesive source in nature, dopamine could be easily adhered to surfaces of organic material and inorganic material via polymerization processes and spontaneous adsorption under weak alkaline pH conditions. To apply the unique features of dopamine, we synthesized Pt–PDA–RGO nanocomposites with a different quantity of dopamine, which are expected to preserve the improved Pt adsorption on graphene, resulting in the enhanced electrocatalytic performance. The morphology and micro-structure were examined by field emission scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. Compared to pristine Pt–deposited RGO (Pt–RGO), Pt–PDA–RGO (30 wt% dopamine against RGO) nanocomposites showed a superior electrochemical active surface area for a methanol oxidation. This could be related to the fact that the optimized c

마라도(제주특별자치도, 서귀포시)의 거미상

김주필(Joo-Pil Kim),예용택(Yong-Taek Ye),최한석(Han-Seok Choi),장지현(Jee-Hyeon Jang):예성훈(Seong-Hun Ye),김태우(Tae-Woo Kim),김대희(Dae-Hee Kim),지승환(Seung-Hwan Ji),이형민(Hyung-Min Lee),이형진(Hyung-Jin Lee) 한국거미연구소 2016 한국거미 Vol.32 No.2

2016년 8월 3일부터 5일까지 제주특별자치도 서귀포시 대정읍 마라도 일대를 한국거미연구회 하계 합동채집회에 김주필, 예용택, 최한석, 장지현, 예성훈, 김태우, 김대희, 지승환, 이형민, 이형진, 신정애, 허양미, 이영경, 최라미, 이윤정 등이 채집조사한 결과 15과, 39속, 45종의 거미류가 조사연구되어 이에 보고하는 바이다. The authors investigated the spiders of the Mara Island in Jeju Island. In the present paper 45 species of 39 genera belong to 15 families were identified. These specimens are deposited at the Joo-Pil Spider Museum, Namyangju-Si, Kyunggi-Do.

MgCl₂溶液內에서 STS 304 HP Stainless Steel 熔接部의 破壞擧動에 對한 硏究

金永奭,丁太權,朴昌彦,洪錫柱,梁仁榮,金基玉,朴煥奎,李茂錫,曺圭宰,鄭在康 조선대학교 생산기술연구소 1983 生産技術硏究 Vol.1983 No.-

This paper is based on an experiment analysing the stress corrosion cracking behaviour of welding specimens compared to that of non-welding specimens of STS 304 HP stainless steel in corrosion solution. As a corrosion condition, stainless steel has been known to be the most fragile in a solution of 42% MgCl₂heated to the boiling point, therefore the experiment was carried out in this condition. The experiment was carried out with argon gas TIG welding specimens and non-welding ones made of stainless steel plates, thickness 2mm, by tensile force. At this time, the tensile force was taken to be the value of the yield strength of the tensile test specimens divided by the safety factor of 3.0 to 3.5, 4.0, 4.5, and 5.0. In this paper, the relations between Time of Initial Crack, Time of Failure, Time of Final Fracture and Crack Propagation Length were investigated and then plotted. Furthermore, the relations between Stress Intensity Factor K proposed by Irwin and the Time of Initial Crack, the Time of Failure, the Time of Final Fracture were calculated and plotted. At the last, all the relations plotted were expressed to normal equations by computer, and the equations were used to analyse the data obtained in the experiment. The conclusions obtained in this study are as follows: 1. Welding materials, compared with non-welding ones, as the Time of Initial Crack, the Time of Failure, and the Time of Final Fracture were generally very fast, appeared to be a phenomenon of unstable brittleness fracture. 2. Non-welding materials, compared with welding ones, as the safety factor was larger or the working stress was smaller, appeared to be a phenomenon that the longer had had greater durability. Therefor, welding materials must be considered enough to be used in heate affected and stress corrosion atmosphere. 3. The normal equations of the Time of Initial Crack and the variation rate to the same Stress Intensity Factor K are as follows: (A) Non-welding T =259702.4-5451.2 K+28.386 K² T = -5451.2+28.386 K (B) Welding T= -332.693+28.043 K-0.211 K² T' =28.043-0.211 K here, T; Time of Initial Crack, T'; Variation Rate of Time of Initial Crack to Stress Intensity Factor K, K ; Stress Intensity Factor.

SUS 304강의 크리이프 온도역에 있어서 피로균열성장거동에 관한 연구

주원식,조석수 동아대학교 공과대학 부설 한국자원개발연구소 1993 硏究報告 Vol.17 No.2

The high temperature fatigue crack growth behavior of Type SUS 304 stainless steel at 550℃ and 650℃ was investigated under various kinds of stress ratios and frequencies in sinusoidal waveform. The result arranging crack growth rate by modified J-integral J' showed influence of stress ratio and frequency. All the data obtained under the test at 550℃ were plotted within data band of da/dN-△J_(f) relationship. Both the time and the cycle dependent crack growth behavior were observed under loading conditions at 650℃, but the cycle dependent crack growth behavior predominantly appeared and the time dependent crack growth behavior was little observed under loading conditions at 550℃. Fractographic examinations for fracture surface indicated that the fracture mode was generally transgranular. The J'_(an) had a validity in case of 650℃, but had scarcely it in case of 550℃

HPLC-MS/MS를 이용하여 혈장 중 레보티인정의 정량분석

채석,오형근,이상선,김형기,손동렬,염윤기,맹주양,권준택 순천향의학연구소 2008 Journal of Soonchunhyang Medical Science Vol.14 No.2

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액체금속로 KALIMER의 가동중검사 및 보수 개념설계

주영상,김석훈,이재한 한국비파괴검사학회 2004 한국비파괴검사학회지 Vol.24 No.2

가동중검사와 보수는 원자력발전소의 원자로계통설계에서 매우 중요한 설계개념이다. 액체금속로 KALIMER의 가동성 검증을 위해서 기계계통 설계에 가동중검사와 보수개념이 반영되어야 한다. 본 연구에서는 KALIMER의 안전성과 신뢰성을 확보하기 위하여 KALIMER의 개념설계 단계에 필요한 가동중검사와 보수의 기본 개념을 설정하였다. 액체금속로 가동중검사 규정인 ASME Section ⅩⅠ Division 3를 반영하고 KALIMER의 설계특성을 고려하여 원자로계통과 주요부품의 가동중검사와 보수에 대한 방법과 요건을 설계하고 기술하였다. The design concepts of in-service inspection and maintenance are very important for the reactor system design of the nuclear power plant. The strategy of in-service inspection and maintenance should be reflected in the mechanical system design for the verification of the operability of liquid metal reactor KALIMER. In this paper the fundamental approaches of the in-service inspection and maintenance of the KALIMER are established to ensure the safety and reliability of the reacter system. The general method and requirement of the in-service inspection and maintenance for the reactor system and components are proposed and described to satisfy the intents of the ASME Section XI Division 3 and the design characteristics of KALIMER.

변형된 C-V피판을 이용한 유두 재건술 : 증례보고

강석주 고신대학교 의과대학 2009 고신대학교 의과대학 학술지 Vol.24 No.1

Nipple reconstruction is an important step in breast reconstruction after mastectomy. For ideal breast reconstruction, final nipple reconstruction should be done with good projection, symmetrical position, shape, and texture. Nowadays, C-V flap is popularly used because of its simple procedure and less donor site morbidity. But, it also has some problems of maintaining good perpendicular nipple projection and the flap could be injured by ischemia from the overloaded tension. We modified the traditional C-V flap to overcome these drawbacks and obtained satisfactory results. We applied modified C-V flap to a 33-year-old female patient whose breast was previously reconstructed with tissue expander. We modified C-V flap design, the tip of the horizontal V-flap was changed into rectangular shape. And, de-epithelization was done on the base of nipple according to the diameter of new nipple. Then a small flap was made, and insetted between the junction of bilateral V-flap to minimize the contracture and inversion of new nipple. After 6 months of follow-up periods, the nipple projection was stable and symmetric. Our experience showed that modified C-V flap could overcome some drawbacks of traditional C-V flap.

근로형태에 따른 장애인근로자의 근로조건 및 직무만족도 차이

주석진,한성덕 한국장애인고용공단 고용개발원 2010 장애와 고용 Vol.20 No.3

본 연구는 장애인의 근로형태에 따라 근로조건과 직무만족도의 차이를 알아보고, 직무만족도에 영향을 미치는 요인을 파악하는데 그 목적이 있다. 연구대상은 한국장애인고용공단 고용개발원이 2008년 수집한 장애인고용패널데이터를 사용하였다(1,211명). 연구 결과는 다음과 같이 요약할 수 있다. 첫째, 근로형태에 따라 학력과 연령에서 차이가 나타났는데, 정규직일수록 학력은 높고, 연령은 낮은 것으로 나타났다. 근로조건 또한 정규직일수록 임금, 근로시간, 복리후생(數), 근속개월이 높은 것으로 나타나고 있다. 둘째, 근로형태에 따라 전반적인 직무만족에 영향을 미치는 요인은 다르게 나타났다. 2 모형에서 정규직의 경우 장애의 중증여부, 중증*학력, 임금, 복리후생(數)가 유의미한 영향력이 있었다. 비정규직의 경우 성별, 중증여부, 학력, 임금, 복리후생(數)가 유의미한 것으로 나타나 근로 조건의 차이가 직무만족에 영향을 미치고 있는 것으로 나타났다. The aim of this study was to identify the differences of working conditions and job satisfaction by working type of disabled workers as well as the factors predicting their job satisfaction. For this, a Panel data(N=1,211) of Employment for the Disabled in 2008 was used. The results were as follows; first, Regular Workers were high in education degree, wage, working hours, employee benefit, length of service, subjective satisfaction degree, but low in age. Second, as for the factors that influenced job-satisfaction, disability type, wage, employee benefits were statistically influential in Regular Workers and sex, disability type, education degree, wage, employee benefits in Irregular Workers. Limitations of the study were discussed, as well as recommendations for additional research.

새로운 방법에 의한 1,1-R,R'-2,3,4,5-테트라페닐-1-실라사이크로펜타디엔의 합성

주완철,흥장환,최석봉 성균관대학교 기초과학연구소 1988 論文集 Vol.39 No.1

A new synthesis of 1,1-R, R',-2, 3, 4, 5-tetraphenyl-1-silacyclopentadiene was described. It was synthesized from one-pot reaction of 1,4-dilithio-1, 2, 3, 4-tetraphenylbutadiene with R_nSiCl_4-n (n=0, 1, 2), where 1, 4-dilithio-1, 2, 3, 4-tetraphenyl butadiene was prepared from the reaction of diphenyl acetylene and lithium metal in ether solution with good yield (80∼85%).

H∞ 최적 제어기법을 이용한 전력시스템의 안정화에 관한 연구

주석민,이용길,정동일,김상효,이오걸 동의공업대학 2000 論文集 Vol.26 No.1

In this paper, we are considered various possible disturbance conditions in order to design controller, H∞ optimal controller is successfully designed to control in such as situations. To do this, we are determined weighting function and design parameter γ to method of trial and error by Glover-Doyle algorithm. To compare with H∞-PSS and conventional-PSS which is applied in nominal system and load variations, the dynamic characteristics of H∞-PSS controller was verified which has a good response.