표면처리된 탄화규소의 첨가가 탄소섬유 강화 복합재료의 열안정성 및 기계적 특성에 미치는 영향

박수진,오진석,서동학 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.5

본 연구에서는 표면처리에 따른 탄화규소(SiC)의 표면특성변화가 탄소섬유 강화 복합재료의 열안정성과 기계적 물성에 미치는 영향을 조사하였다. 표면처리된 탄화규소의 표면특성은 산·염기도, 접촉각측정 그리고 FT-IR을 통하여 알아보았으며, 열안정성은 TGA를 이용하여 조사하였다. 탄소섬유 강화 복합재료의 기계적물성은 interlaminar shear strength(ILSS) 그리고 critical strain energy release rate mode Ⅱ(G_(IIC))를 통하여 고찰하였다. 실험결과 산 처리된 SiC(A-SiC)와 오존처리된 SiC(0-SiC)는 미처리된 SiC(V-SiC)나 염기 처리된 SiC(B-SiC)에 비하여 산도가 증가하였고, 접촉각 측정 결과, 산성 용액과 오존 표면처리는 극성요소의 증가에 기인하는 SiC의 표면자유에너지를 증가시켰다. ILSS과 G_(IIC) 같은 기계적 계면 성질은 A-SiC와 O-SiC로 향상되어졌는데, 이러한 결과는 좋은 젖음성이 최종 복합재료의 SiC와 에폭시 수지 매트릭스 사이의 계면결합력을 증가시키는 중요한 역할을 하기 때문으로 판단된다. In this work, the effect of chemically wet and dry treatments of SiC was investigated in mechanical interfacial properties of carbon fibers-reinforced composites. The surface properties of Sic were determined by acid/base values, contact angles, and FT-IR analyses. The thermal stabilities of the carbon fibers-reinforced composites were investigated by thermo-gravimetric analysis (TGA). Also, the mechanical interfacial properties of the composites were studied in interlaminar shear strength (ILSS) and critical strain energy release rate mode Ⅱ(G_(ⅡC)) measurements. As a result, the acidically treated SiC (A-Sic) and ozone treated (0-Sic) had higher acid value than that of untreated Sic (V-Sic) or basically treated Sic (B-Sic). According to the contact angle measurements, it was observed that acidic solution and ozone treatments led to an increase of surface free energy of the SIC surfaces, mainly due to the increase of the specific (polar) component. The mechanical interfacial properties of the composites, including ILSS and G_(ⅡC) had been improved in the specimens treated by acidic solutions and ozone gas. These results were explained that good wetting played an iniportant role in improving the degree of adhesion at interfaces between SiC and epoxy resin matrix in a composite system

양극산화된 탄소섬유/에폭시 복합재료의 크랙저항 특성

박수진,오진석,서동학 한국화학공학회 2004 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.42 No.1

본 실험에서는, 양극산화 처리된 탄소섬유의 표면 변화가 탄소섬유 강화 에폭시 복합재료의 크랙저항 특성에 미치는 영향에 대하여 고찰하였다. 탄소섬유의 표면처리 전후 표면특성 변화는 산-염기도, FTR-IR, XPS 그리고 접촉각 측정을 통하여 알아보았고, 복합재료의 크랙저항 특성은 임계에너지 방출 속도 Ⅰ(critical energy rate, G_(Ic))와 임계에너지 방출 속도 Ⅱ(critical energy rate mode Ⅱ, G_(IIc))의 두 가지 방법을 통하여 고찰하였다. 실험결과, 탄소섬유 표면의 표면 산도와 O_(IS)/C_(IS) 비율이 증가하였는데, 이는 탄소섬유의 산성관능기와 표면자유에너지의 극성요소 증가에 기인하는 것으로 판단된다. 복합재료의 G_(Ic)그리고 G_(IIc)같은 기계적 계면성질은 탄소섬유의 양극산화로 향상되어졌는데, 이는 산성관능기들의 증가에 따른 탄소섬유와 매트릭스와의 계면 결합력의 증가에 기인하는 것으로 판단된다. Anodic oxidation on the surfaces of carbon fibers was carried out to enhance the mechanical interfacial properties of carbon fibers-reinforced epoxy matrix composites. And the surface characteristics of untreated and treated carbon fibers were studied by FT-IR, XPS, and contact angle measurements after modifications. Crack resistance of the composites was investigated using by two types of testing method, namely critical energy release rate mode Ⅰ(G_(ⅠC)) and mode Ⅱ(G_(ⅡC)). The O_(IS)/C_(IS) ratio of the carbon fibers was increased after anodic treatment, due to the introductions of the oxygen-containing functional groups, or the specific components of surface free energy of the carbon fibers. It was found that the mechanical properties at interfaces, including G_(ⅠC) and G_(ⅡC) of the composites had been improved by the oxidation, which could probably be attributed to the increase of the degree of adhesion at interfaces between fibers and resin matrix in the composite system.

중소건설업체 ISO 9002 인증 문제점과 대책

박영호,송학진 동의공업대학 1999 論文集 Vol.25 No.1

Over the last few years Total Quality Management(TQM) programs have been widely adapted by the Korean construction companies to improve their productivity, competitive edge, and product quality level. Many companies have been proceeding or have completed the development of quality system since 1992. However medium and small size construction companies have many difficulties due to lack of understanding, cooperation of top or related management, money and man power. In this paper the problems of the minor construction companies are picked out through the case study of D construction company in Pusan and then countermeasures which can be efficiently applied to the development and operation of quality management system are suggested to help the medium and small construction companies that want to adopt the quality management system.

MO이론에 의한 Diels-Alder 반응의 배향성과 반응성의 결정(Ⅰ)

丁學鎭,金一斗,朴聖珪 조선대학교 기초과학연구소 1985 自然科學硏究 Vol.8 No.1

This paper aims to predict the reactivity and the regioselectivity of Diels-Alder reactions of unsymmetical dienes and dienophiles. Frontier orbital theory has been applied to thermal Diels-Alder reaction by means of CNDO/2 and EHT-spd methods. The above reactions are normal electoron demand reaction and the major regioisomer is the para-substituents that is identical with experiments. Four-frontier orbitals and two-frontier orbitals' methods are identical with experimental major regioisomers. Sulfur is a much more polarizing substituent for the dienes than chlorine and cyanoradical. When sulfur is in diene, it shall dominate the regioselectivity. The coefficient polarization of substituted dienes and dienophiles is the same direction. We can predict the major regioisormer as para-substituents.

벤처기업 성공요인의 중요도

송학진,박영호 동의공업대학 1999 論文集 Vol.25 No.1

This study reports the importance of success factors for high-tech ventures based on the survey of DIT Business Incubator's ventures. We classified the success factors of high-tech ventures into four major groups and inquired about K and D ventures of DIT Business Incubator. The AHP method was applied to analyze the data. The result of analysis shows that the adequate opportunities(market opportunity, technical opportunity) and the resources security(technical resources, man power resources) are very important factors for high-tech ventures' success.

정신과 문제로 병사용 진단서를 발급받은 환자들의 임상적 특징

장혁진,김학렬,박상학,김상훈,조용래,표경식 조선대학교 2001 The Medical Journal of Chosun University Vol.26 No.2

Background and Objectives : Most Korean young men should take a military physical examination. This study attempted to search the social, economical and psychological features of Korean youths who have psychiatric problems in taking the military physical examination. So this study was intended to help decide whether the youths enter the military service or not. Materials and Methods : This study analyzed diagnostic features that were grouped by 7 categories (antisocial and borderline personality disorder group, the other personality disorders group, psychosis group, organic mental disorder group, neurosis group, pervasive developmental disorders group, the other groups). The study was conducted from 1994 to May 1999 at Chosun University hospital with about 143 patients who were issued the psychiatric certificate for military affairs. Results : According to the results of the psychiatric examination, the antisocial and borderline personality disorder group had increased more year by year than the other groups. Classified by the residential distribution, the residents of agricultural areas belonged to the psychosis group more than others. Classified by the job distribution, the antisocial and borderline personality disorder group had more gangsters than the other groups. Also the pervasive developmental disorders group included those Who were without an occupation. Classified by visiting companion, those who were included in the antisocial and borderline personality disorder group and pervasive developmental disorders group used to come alone as compared with the other groups. In the case of those who have experienced psychiatric treatment in the past and who have been treated psychiatrically after being given the psychiatric certificate, the psychosis group comprised more than 50% statistically. In the case of the existence of a tattoo and self-injured scars, the antisocial and borderline personality disorder group has more than the others statistically. According to psychological examination, by measure of validity scale of MMPI, the antisocial and borderline personality disorder group appeared as the inverted V shape that L, K value was low and F value was high. And the antisocial and borderline personality disorder group measured by the Pd, Pa measure. Pd, Pa measure value got higher points than the organic mental disorder group statistically. Conclusion : The number of the antisocial and borderline personality disorder patients’ visits increased at the psychiatric hospital year by year and there were many gangsters or persons without regular occupation in that kind of patients’group. And there were many visitors who came by themselves to the hospital. Also they tended to have a tattoo or self-injured scars. And most of patients didn’t do commuting psychiatric care after receiving the psychiatric certificate. In the aspect of the psychological examination, they were likely to exaggerate their symptoms or disguise having psychiatric trouble intentionally.

붓스트랩을 이용한 EWMA관리도의 수행도 평가

송학진,박영호,이만웅 동의공업대학 2001 論文集 Vol.27 No.1

In this study, we establish bootstrap control limits for EWMA chart by applying the bootstrap method, called resampling, which could not demand assumptions about pre-distribution when the process is skewed and/or the normality assumption is doubt. The results obtained in this study are summarized as follows : bootstrap EWMA control chart is developed for applying bootstrap method to EWMA chart, which is more sensitive to small shifts of process. With the purpose of eliminating a skewness of the resampling distribution, the bootstrap control limits are established by using a modified residual, and its performance is analyzed by ARL. It is shown that the bootstrap EWMA control chart developed in this study includes the properties of standard EWMA control chart that is sensitive to a small shift, and detects process in out of control more quickly than standard EWMA chart.

정신과를 방문하는 환자의 통증호소의 빈도 및 특성

송지영,박진철,박종학,오동재,손형석,정근재 大韓神經精神醫學會 1999 신경정신의학 Vol.38 No.6

연구목적: 정신과 방문 환자에서 통증 호소는 적지 않을 것이라고 알려져 있으나 국내에서 정신과 외래 환자의 통증 관련 연구는 부족한 실정이다. 이에 정신과 외래에 오는 환자들에서 통증의 빈도와 특성을 1,2,3차 의료기관에서 알아보고자 하였다. 대상과 방법: 1차 의료기관(개인정신과의원) 외래환자 298명, 2차 의료기관(종합병원) 정신과 외래환자 99명, 3차 의료기관(대학병원) 정신과 외래환자 446명으로 총 843명의 성인 남녀를 대상으로 이들이 정신과에 방문했을 당시의 통증 여부와 조사 당시의 통증 유무 및 현재 통증의 정도를 평가하였다. 그리고 기질적 원인의 여부, 만성 통증의 여부, 통증의 부위, 통증 악화 요인, 보상문제의 유무, 약물 투여 내용 등을 조사하였다. 결 과: 1) 전체 대상자 843명 중 통증이 동반되었던 환자의 비율은 41.3%였으며, 기관별로 보면 개인의원 44.9%, 종합병원 44.5%, 대학병원 38.1%였다. 2) 조사 당시에 통증을 갖고 있는 경우는 3개 기관에서 평균 24.1%였다. 통증의 정도는 VAS상 평균 46.7㎜였으며 개인의원에서 대학병원에 비해 의미있게 그 정도가 심했다. 또한 `강하다` 이상의 통증 정도를 호소한 경우는 34.0%, `괴롭다` 이상의 불쾌정도를 표현한 경우는 26.2%였다. 3) 통증이 있었던 환자 중 기질성이 뚜렷한 경우는 적었으며(1.5∼5.9%), 통증의 부위는 머리가 50.9%로 가장 많았다. 통증의 지속기간은 6개월 이상인 만성통증의 경우가 68.7%를 차지했다. 4) 주요 약물로는 항불안제가 41.4%로 가장 많이 사용되고 있었으며, 통증과 관련하여 진통제를 처방받는 환자는 3.2%에 불과하였다. 결 론: 정신과 외래를 방문하는 환자들의 통증의 특성은 의료기관에 따라 인구통계학적 차이 뿐만 아니라 진단분포도 다르므로 3기관을 직접 비교하기에는 무리가 있으나, 본 연구 조사 결과 정신과 외래를 방문하는 환자들 중에서 40% 이상이 통증을 경험하고 있으며 2/3이상은 만성 통증이라 할 수 있었다. 이들은 중등도 이상의 통증을 갖고 있으며 당장 통증을 해결해 주어야 할 숫자도 적지 않았다. 따라서 정신과 환자의 통증에 대한 평가와 관리가 앞으로 더욱 강조되어야 할 필요가 있다고 사료된다. Objectives: The purposes of this study were to investigate the frequency and clinical characteristics of pain among the psychiatric out-patients in three clinics. Methods: A Total of 843 psychiatric adult out-patients(298 subjects from a private clinic, 99 subjects from a general hospital, 446 subjects from a university hospital) were assessed for the presence of pain during OPD follow-up and at the time assessed. And, the presence of organic causes, duration and site of pain, aggravating factors, compensation problems, and prescribed drugs were also investigated. Results: 1) The frequency of pain among psychiatric out-patients was overall 41.3%(44.9% in private clinic, 44.5% in general hospital, and 38.1% in university hospital, respectively). 2) The frequency of pain at the time assessed was 24.1%. In severity of pain, the average of VAS was 46.7±18.0㎜. Patients of private clinic showed more severe pain than that of general hospital. Moreover, patients who experienced over `marked` occupied 34.0% and pain as over `distressed` occupied 26.2%. 3) Only a few subjects had the definite organic causes(1.5-5.9%). The most common site of pain was on head. The patients having a pain over 6 months(i.e. chronic pain) occupied 68.7%. 4) The most common drugs prescribed were anxiolytics; 41.4% of patients were prescribed. The analgesics were prescribed only in 3.2% of patients. Conclusion: This result revealed that more than 40% of patients experienced pain in psychiatric OPD and two third of patients were suffered from chronic pain. Therefore, the evaluation and management of pain should be more emphasized.

Lifestyle Modification in the Management of Metabolic Syndrome: Statement From Korean Society of CardioMetabolic Syndrome (KSCMS)

Hack-Lyoung Kim,Jaehoon Chung,Kyung-Jin Kim,Hyun-Jin Kim,Won-Woo Seo,Ki-Hyun Jeon,Iksung Cho,Jin Joo Park,Min-Ho Lee,Jon Suh,Sang-Yup Lim,Seonghoon Choi,Sang-Hyun Kim 대한심장학회 2022 Korean Circulation Journal Vol.52 No.2

With the recent rapid increase in obesity worldwide, metabolic syndrome (MetS) has gained significant importance. MetS is a cluster of obesity-related cardiovascular risk factors including abdominal obesity, atherogenic dyslipidemia, high blood pressure and impaired glucose tolerance. MetS is highly prevalent and strongly associated with an increased risk of developing diabetes and cardiovascular disease, putting a great burden on human society. Therefore, it is very important to reduce MetS risk, which can improve patients’ cardiovascular prognosis. The primary and most effective strategy to control each component of MetS is lifestyle change such as losing body weight, keeping regular exercise, adopting a healthy diet, quitting smoking and alcohol drinking in moderation. Many studies have shown that lifestyle modification has improved all components of MetS, and reduces the incidence of diabetes and cardiovascular disease. Here, the Korean Society of CardioMetabolic Syndrome has summarized specific and practical methods of lifestyle modification in the management of MetS in the healthcare field.

A Simple Method for Reconstruction of the Temporalis Muscle Using Contourable Strut Plate after Pterional Craniotomy: Introduction of the Surgical Techniques and Analysis of Its Efficacy

Jin-Hack Park,Yoon-Soo Lee,Sang-Jun Suh,Jeong-Ho Lee,Kee-Young Ryu,Dong-Gee Kang 대한뇌혈관외과학회 2015 Journal of Cerebrovascular and Endovascular Neuros Vol.17 No.2

Objective:Pterional craniotomy (PC) using myocutaneous (MC) flap is a simple and efficient technique; however, due to subsequent inferior displacement (ID) of the temporalis muscle, it can cause postoperative deformities of the muscle such as depression along the inferior margin of the temporal line of the frontal bone (DTL) and muscular protrusion at the inferior portion of the temporal fossa (PITF). Herein, we introduce a simple method for reconstruction of the temporalis muscle using a contourable strut plate (CSP) and evaluate its efficacy. Materials and Methods:Patients at follow-ups between January 2014 and October 2014 after PCs were enrolled in this study. Their postoperative deformities of the temporalis muscle including ID, DTL, and PITF were evaluated. These PC cases using MC flap were classified according to two groups; one with conventional technique without CSP (MC Only) and another with reconstruction of the temporalis muscle using CSP (MC + CSP). Statistical analyses were performed for comparison between the two groups. Results:Lower incidences of ID of the muscle (p < 0.001), DTL (p < 0.001), and PITF (p = 0.001) were observed in the MC + CSP than in the MC Only group. The incidence of acceptable outcome was markedly higher in the MC + CSP group (p < 0.001). ID was regarded as a causative factor for DTL and PITF (p < 0.001 in both). Conclusion:Reconstruction of the temporalis muscle using CSP after MC flap is a simple and efficient technique, which provides an outstanding outcome in terms of anatomical restoration of the temporalis muscle.