Proposal of New Biaxial Fatigue Life Prediction Parameter by Using the Effective Shear Stress for CF8M Stainless Steels

Park, Joong Cheul,Kwon, Jae Do Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.297 No.-

<P>A combined axial-torsional low cycle fatigue test was carried out to predict the fatigue life under in-phase and out-out-phase loading conditions for CF8M cast stainless steels. The Fatemi-Socie (FS) parameter which is based on the critical plane approach is not only one of the many methods but also the best method that can predict the fatigue life under a biaxial loading condition. But the result showed that, a biaxial fatigue life prediction by using the FS parameter with several different parameters for the CF8M cast stainless steels is not conservative enough but at the same time it was the best result so far. So in this present research, we proposed a new fatigue life prediction parameter (Park-Kwon parameter) by considering effective the shear stress instead of the FS parameter which considers the maximum normal stress acting on the maximum shear strain and its effectiveness was verified.</P>

물리 문제 해결 과정에서의 학생들의 사고 과정에 관한 연구

박학규,권재술 한국교원대학교 과학교육연구소 1994 청람과학교육연구논총 Vol.4 No.1

The purpose of this study was to analyze students' physics problem solving processes and to find the patterns of their problem spaces when high school and university students solved the physics problems. A total of 51 students in a high school and in two universities participated in this study. Their thinking processes in solving 5 physics problems on electric circuit were recorded by using 'thinking aloud' method and were transfered into protocols. The protocols were analyzed by the coding system of problem solving process. One of the major theoretical contributions of the computer simulation approach to problem solving is the idea of problem space. Such a concept of problem space was applied to physics problems on electric circuit in this study, and students' protocols were analyzed by the basic problem spaces which were made up from the item analysis by the researcher. The results are as follows: 1) On the average 4.0 test items among 5 ones were solved successfully by all subjects, and all of the items were solved correctly by only 19 persons among all of them. 2) In regard to the general steps of problem solving process, there was little difference for each item between the good solvers and the poor ones. But according to the degree of difficulty of task there was a good deal of difference. For a complex problem all of 4 steps were used by most of students, but for a simple one only 3 steps except evaluating step were used by most of them. 3) It was found in this study that most of students used mainly the microscopic approach, that is, a method of applying Ohm's law on electric circuit simply and immediately, not using the properties of electric circuits. And also it was observed that most of students used the solving from below, that is, a solving path in which they were the first to calculate physical quantities of circuit elements, before they caught hold of the meaning of the given problem regardless of the degree of difficulty.

醫藥分業에 대한 保健所 公務員들의 認識과 態度

박석수,박재용,권진희 경산대학교 보건복지연구소 2000 保健福祉硏究 Vol.5 No.-

This research was conducted to find the attitude of public health officials about the division of roles between doctors and pharmacists (DRDP) which would be committed from July 01, 2000. The survey was carried out for the 600 public health officials from 25 health centers between March 2, 2000 and March 31, 2000 in Kyoungsan-Bukdo area. 33.0% of respondents were highly aware of the DRDP, and 63.0% were moderately aware of the DRDP. The proportions of the respondents who recognized that the health center should include DRDP agency are 43.3% among the health officials, 25.8% among the administrative officials, 80.0% among the drug relating officials, and 60.0% among the temporary officials. 65.3% of respondents answered that exceptions of DRDP should be allowed in some cases, such as, in areas where there is no medical facilities or pharmacies. 58.0% responded that the network system between pharmacies and medical facilities should be necessary so that the exchange of information is allowable in case that the prescribed medicine is not in the pharmacies. 30.0% agreed that the abuse of injections should be prevented, and 41.2% responded that the health center should emphasize public relations when there is any inconvenience to implement the injection. 65.3% were that there is little inconvenience about substitution of preparation of medicine, and 28.2% were that the strengthening of the administrative action by the pharmaceutical affairs law might be useful in order to improve patients convenience. The participants supported that a doctor can prepare patients medicine for an emergency patient (97.7%) and the first infectious disease (96.5%). The participants also supported that a pharmacist can prepare patients medicine for the areas of no medical facilities (79.3%) and disaster areas (78.8%). The participants were affirmatively showed about the system of using community drug sotre (helpful (66.5 percent) and not helpful (33.5 percent)) and the fuction of the primary medical institutions, that is, the family doctor system (helpful (81.8%) and not helpful (18.2%). The participants also recognized that the regional cooperation committees would be helpful to minimize patients inconvenience. Officials participated in this survey responded that education of residents and the public information by consumers cooperative institution would produce the most efficient effect. This study can be concluded that the recognition of health officials varies by the education level, job position level, and primary duty. Therefore, the education of DRDP for health officials is necessary for improvement of their ability and knowledge and for the smooth introduction of the division between medical roles.

유전체의 과도 산란 해석을 위한 시간영역 결합 적분방정식

박재권,김형진,윤희상,정백호 湖西大學校工業技術硏究所 2003 工業技術硏究所論文集 Vol.22 No.-

In this paper, we propose a time domain combined field integral equation (TD-CFIE) formulation to analyze the transient electromagnetic response from three-dimensional dielectric objects. The solution method in this paper is based on the method of moments(MoM) that involves separate spatial and temporal testing procedures. A set of the RWG(Rao, Wilton, Glisson) functions is used for spatial expansion of the equivalent electric and magnetic current densities and a combination of RWG and its orthogonal component is used as spatial testing. We also investigate spatial testing procedures for the TD-CFIE to select the proper testing functions that are derived from the Laguerre polynomials. These basis functions are also used for temporal testing. Numerical results computed by the proposed formulation are presented and compared with the solutions of the frequency domain combined field integral equation(FB-CFIE).

mRNA의 3' end processing에 대한 mRNA 중합요소 인산화의 영향

권대환,박재현,송영하,안성훈 한양대학교 이학기술연구소 2006 이학기술논문지 Vol.9 No.-

RNA 중합효소의 C-terminal은 YSPTSPS의 반복적인 아미노산 서열을 갖고 있으며, 이들의 인산화는 전사의 개시, 중합, 또는 종결단계에 중요하다고 알려져 있다. 본 연구에서는 이러한 RNA 중합효소의 인산화가 mRNA의 3' end processing에 미치는 영향을 조사하였다. C-terminal domain (CTD) of RNA polymerase Ⅱ contains a repeated heptameric sequence (YSPTSPS) which is phosphorylated at serine 2 and 5. Phosphorylation of CTD in elongating RNA polymerase Ⅱ has been suggested to play a role in transcriptional initiation, elongation or termination. In the present study, we investigated the effect of RNA polymerase Ⅱ CTD phosphorylation on the 3' end processing of mRNA.

신장에 발생한 섬유육종 1례

이재규,손경민,권동득,오봉렬,류수방,박양일,최찬 大韓泌尿器科學會 2001 Korean Journal of Urology Vol.42 No.7

자가부식 프라이머 접착제의 적용방식이 법랑질의 결합강도에 미치는 영향

박재구,조권환,조영곤 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.2

The purpose of this study was to evaluate the effect of passive or active application of primer and coat times of bond on the shear bond strength when a self-etching primer adhesive (Clearfil SE Bond) was applied to enamel surface. Crowns of sixteen human molars were selected. Buccal and lingual enamels of crowns were partially exposed and slabs of 1.2 mm thick were made. They were divided into one of four equal groups (n = 8). Group 1: passive application of Primer and 1 coat of Bond, Group 2: active application of Primer and 1 coat of Bond, Group 3: passive application of Primer and 2 coats of Bond, Group 4: active application of Primer and 2 coats of Bond. Clearfil AP-X was bonded to enamel suface of each group using Tygon tubes. The bonded specimens were subjected to microshear bond strength (uSBS) testing with a crosshead speed of 1 mm/min. The results of this study were as follows; 1. The uSBS of Group 1 was the lowest among groups and the uSBS of Group 4 was the highest. 2. There was not statistically significant interaction between enamel uSBS by application method of Primer and coat time of Bond (p > 0.05). 3. There was not statistically significant difference between enamel uSBS by passive and active application of Primer (p > 0.05). 4. There was statistically significant difference between enamel uSBS by one- and two-coat of Bond (p < 0.05). 이 연구는 Clearfil SE Bond를 거친 법랑질 표면에 적용할 때, 자가부식 프라이머의 적용방식 (능동적인 또는 수동적인)과 접착레진의 도포회수 (1회 또는 2회)가 법랑질의 결합강도에 미치는 영향을 알아보기 위하여 시행하였다. 16개의 발거된 대구치 치관의 협면이나 설면에서 법랑질 절편을 만들어 4개의 군으로 배정한 다음, 1군은 프라이머를 수동적으로 적용한 후 접착레진을 1회 도포하였고, 2군은 프라이머를 능동적으로 적용한 후 접착레진을 1회 도포하였고, 3군은 프라이머를 수동적으로 적용한 후 접착레진을 2회 도포하였고, 4군은 프라이머를 능동적으로 적용한 후 접착레진을 2회 도포하였다. 적용된 접착레진을 10초간 광조사한 후, 법랑질 표면에 2-3개의 Tygon tube를 위치시키고 Clearfil AP-X를 충전하고 40초간 광조사 하였다. Universal testing machine을 이용하여 법랑질 표면에서 복합레진이 파절될 까지 분당 1.0 mm의 cross-head speed로 전단하중을 가하고 통계적으로 분석하여 다음과 같은 결과를 얻었다. 거친 법랑질에 대한 Clearfil SE Bond의 미세전단 결합강도는 자가부식 프라이머의 적용방식 보다는 접착레진의 도포회수에 의해 증가할 수 있음을 알 수 있었다.

光彈性 實驗에 의한 Stress Intensity Factor의 決定法에 關한 硏究

朴熙代,權在度 영남이공대학 1974 論文集 Vol.3 No.-

The mathematical and experimental solutions in regard to the crack tip stress intensity factors has been increased recently in terms of both quality and quantity. The determination of stress intensity factors by stess analysis through photoelastic method often provides the criterion available to the actual design problems. In this paper, the very mehhod was applied to the determination of stress intensity factor around the crack tip in a plane which was subjected under combined shear and tension. For the distribution of stress around the crack tip which has root radius of p=0.25mm, the theoretical formula was determined by shear difference method and confirmed that the formula has slightest difference in value compared with that of experiment.

임신부 뇨로부터 정제된 인간 상피세포 증식 인자 유사체의 in vitro bioassay 및 특성

박세철,전재현,남정현,권태종,고인영,유광현 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1996 한국미생물·생명공학회지 Vol.24 No.4

벤조산흡착, 음이온 교환수지, 단일클론항체을 이용한 immunoaffinity chromatography를 통하여 임신부 뇨로부터 천연의 hEGF를 정제하였다. 정제된 hEGF는 μ Bonda C_18 column을 사용한 HPLC 분석을 통하여 4개의 fraction으로 분리가 가능하였으며 western blot과 double immunodiffusion 실험 결과, 각각의 fraction이 hEGF의 특성을 가진 유사체인 것을 알 수 있었다. 또한 hEGF 표준 물질과의 spiking 및 아미노산 분석 등을 통하여 두 번째 fraction이 nhEGF와 동일한 것으로 확인하였다. nhEGF 및 그 유사체의 생물학적 활성 비교를 위하여 NIH 3T3 세포주에서 5'-Brdu incorporation 측정을 위한 labelling 시간, 혈청 농도의 최적 조건을 결정하였다. NIH 3T3 세포주의 DNA 합성능은 0.2% FCS가 포함된 저혈청 배지에서 hEGF가 0.1~10 ng/ml 농도로 첨가하였을 때 증가하는 경향을 나타냈다. HPLC를 통하여 분리된 두번째 hEGF 유사체가 다른 유사체보다도 생물학적인 활성이 우수하였으며, rhEGF 표준물질과의 spiking 및 아미노산 서열 분석등을 통하여 nhEGF로 밝혀졌다. 임신부의 뇨의 hEGF 유사체 함량중 natural hEGF는 46%이었다. Natural human epidermal growth facto (nhEGF) was purified from pregnant human urine by benzoic acid adsorption, DEAE-Sepharose ion exchange, and immunoaffinity chromatography. The purified nhEGF was further separated into four fractions using Bondapak C_18 HPLC system. Following characterization by Western blot and double immunodiffusion, we found that each fraction corresponds to four derivatives of the nhEGF. For biological analysis of nhEGF, we optimized the labeling time and serum concentration for the incorporation of 5-bromo-2'-deoxy-uridine (BrdU), a non-radioactive alternative for [^3H]-thymidine uptake, into NIH 3T3 cells. The DNA synthesis of NIH 3T3 cells was gradually increased at the nhEGF concentrations between 0.1~10 ng/ml in the Dulbecco's Modified Eagles Medium (DMEM) containing 0.2% Fetal calf serum (FCS). When we assayed the biological activity of four fractions, the activity of the second fraction was superior to that of the others.

과학학습에서 불일치 상황에 대면한 초등학생의 인지갈등 측정 도구 개발

박상석,이경호,김정환,권혁구,권재술 한국교원대학교 과학교육연구소 1999 청람과학교육연구논총 Vol.9 No.1

The purpose of this study was to develop an Instrument for the Measurement of Cognitive Conflict Levels of students who confronted with an anomalous situation in science learning. Anomalous situation is generated when students' prediction is disconsistent with the observed fact. In this study, the researchers identified 4 components of cognitive conflict and developed three items for each component. The items were developed and revised by four pilot tests. In the first pilot test, 55 elementary school students participated in the test. In the second pilot test, 88 students of the 5th and 6th grader participated in the test. The instrument of measuring cognitive conflict levels was given to the subjects right after demonstrating anomalous situation. For the demonstration, two different problem situations were developed: one was a pulley problem and the other was electric bulbs in parallel. Answered reasons for each items were analyzed to assess students' understanding on each items. In third pilot test, 125 elementary school students participated in the test. A factor analysis of the responses was carried out and reliability of the test was assessed by calculating internal consistency values. The items were finalized by three pilot tests. After 1 month after the third pilot test, researchers conducted the finalized test items to 323 students of the 5th and 6th grader. The final instrument showed moderate reliability (Cronbach-α 0.82∼0.87) and good content validity(0.93). A factor analysis of the response was carried out. 4 main factors completely coincided with 4 components that we supposed to be the conducts of cognitive conflict. The instrument can provide a means for both teachers and researchers to assess the cognitive conflict of a large number of students within a single class period. The results can be used by teachers to better understand the process of conceptual change of their students and to match instruction and materials accordingly.