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        Coating with boron nitride on SiC fiber using atomic substitution

        Woo‑Seong Tak,Jin‑Uk Hwang,Young‑Keun Jeong,Woo‑Sik Kim 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.2

        To increase the mechanical properties of ceramic matrix composite, it is important that formation of lubricant layer for crack deflection between matrix and fiber. Therefore, we fabricated uniform boron nitride (BN) lubricant layer using atomic substitution method. Silicon carbide (SiC) fiber surface was modified with amine groups using (3-amonipropyl)triethoxysilane to coat SiC fiber with BN as a solid lubricant. Then, surface was coated with graphene oxide (GO). Boric acid powder was supplied to the GO-coated fibers and the samples were heat-treated at 1200–1400 ℃ under N2 and NH3 atmospheres. An uniform BN layer could be coated on SiC fiber with 10 nm-1.11 μm. Crystallinity and thickness of BN layer could be controlled by reaction temperature. It was also confirmed that crystalline BN formed under process conditions of higher than 1400 ℃.

      • 항암화학요법 중 호중구감소증이 발생한 저위험군 발열 환자들을 대상으로 한 경구 항균제 요법의 임상적 유용성 및 안정성에 대한 연구

        김연숙,이혁,기현균,김춘관,김신우,김성민,백경란,김원석,윤성수,이홍기,강원기,박찬형,박근칠,송재훈 대한화학요법학회 2000 대한화학요법학회지 Vol.18 No.1

        목적 : 항암화학요법 중 호중구감소증을 동반한 발열이 발생하는 암환자들을 치료하기 위한 다양한 항균제와 여러 가지 방법들이 시도되고 있는 가운데, 합병증과 사망률의 발생가능성이 적은 저위험군 환자들을 대상으로 초기 72시간동안 정주 항균제를 투여한 이후 경구 항균제로 전환하는 요법의 유용성과 안정성을 평가해보고자 본 연구를 시행하였다. 방법 : 1998년 2월부터 1999년 9월까지 본원에서 항암화학요법 중 호중구감소증과 발열이 발생한 환자들 가운데 기저 암질환이 고형암이거나 림프종이고, 입원당시 패혈증의 증후가 없으며 입원 72시간이내에 해열되고 백혈구수치가 증가 추세인 환자들을 대상으로 하여 72시간 동안 정주 항균제를 투여한 이후 경우 ciprofloxacin 750㎎을 하루 2회씩 투여하여 총 4일간 투여하였다. 모든 환자들은 열이 떨어지고 호중구감소증이 회복될 때까지 입원하도록 하였다. 결과 : 총 38명 환자의 40예가 등록이 되었고, 환자들의 기저암 질환은 고형함이 72.5%, 림프종이 27.5%였다. 입원당시 평균 호중구치수는 156/㎕였고, 호중구수치가 100/㎕미만인 경우는 65%였으며, 호중구감소증이 지속된 기간의 평균은 2.4일이었다. 40예 중 39예가 항균제의 변형이나 추가 없이 호중구감소증과 발열로부터 회복이 되어 97.5%의 성공율(95% 신뢰구간: 86.8-99.9%)을 보였다. 부작용으로 피부발진이 있었던 경우가 한 예 있었는데, 증상이 경하여 경구 항균제를 지속할 수 있었다. 심와부의 동통으로 복용을 지속할 수 없어서 대상에서 제외된 예가 또 한 예 있었다. 결론 : 항암요법 중 호중구감소증과 발열을 동반한 환자들 가운데 저위험군 환자들에서 항균제 72시간정주 이후 경구 항균제로의 전환요법은 효과적이고도 안전한 치료방법이라고 할 수 있다. Background : Oral antibiotic therapy following empirical intravenous antibiotics may be effective and safe for febrile neutropenic patients with lowrisk for complications. Methods : We conducted a prospective clinical trial of oral antibiotic therapy in the patients with neutropenia and fever during chemotherapy for cancer. Underlying malignancies were solid tumor or lymphoma with short duration of neurtropenia and the patients had no evidence of clinically or microbiologically documented infections. Oral ciprofloxacin was given to the patients who lacked signs of sepsis on admission, had a rising tendency of neutrophil count (ANC >100 /㎕ ) at 72 hours, and were afebrile at 72 hours. All patients were hospitalized until neutropenia and fever resolved. Results : A total of 40 episodes of 38 patients were enrolled from February 1998 to September 1999. The mean neutrophil counts on admission were 156/㎕ and the mean duration of neutropenia was 2.4 days. The episodes which had neutrophil count below 100 /㎕ were 26 (65%). Treatment was successful in 39 of 40 episodes (97.5% : 95 % confidence interval, 86.8% to 99.9%). Adverse reactions of oral ciprofloxacin were skin rash and epigastric soreness in two cases, respectively. There were no deaths during the study. Conclusions : For low-risk febrile patients with neutropenia during cancer chemotherapy, switch therapy to oral ciprofloxacin at 72 hours following intravenous broad-spectrum antibiotics is effective and safe,

      • RISS 인기논문

        수면량과 집중력의 상관관계

        김병우,류지근,박우진,박계원,김미정,임지은,백대현,최재덕,최윤호,이가현,이관,김덕수 東國大學校醫學硏究所 2002 東國醫學 Vol.9 No.1

        수면, 기억 그리고 학습의 연관성은 실제 매우 복잡하다. 많은 연구에도 불구하고 명확한 연구결과는 아직 없다. 우리는 이 연구에서 평소와는 달리 시험 전날 수면 변화 양상이 집중력에 어느 정도 영향력을 미치는지 알아보고자 하였고, 이를 이용해 효율적인 수면 관리를 할 수 있는 기초자료로 삼고자 하였다. 동국대 의대 본과 1학년생 중 지원자 30명과 본과 2학년생 10명을 대상으로 평상시 상태와 시험 직후 수면이 부족한 상태에서 각각 K-PES TEST를 실시하여 총 8항목에 걸쳐 암기력, 판단력, 단순반응의 변화정도를 검사하였다. 또 설문조사를 병행하여 결과에 영향을 미칠 수 있는 다른 인자들도 파악하였다. 수면량에 대한 부호 숫자 짝짓기(순간 판단력)을 검사한 결과, 인간의 최대 생리학적 기능은 꼭 수면부족에 의해 좌우되는 것은 아니다. 그러나, 수면감소는 피로를 증가시키고, 동기부여를 감소시키나 단, 새로운 사실을 학습하는 데에는 큰 영향을 끼치지 않는다. 즉, 수면부족으로 장시간 깨어있는 것은 정확성과 반응성을 떨어뜨린다. 흡연에 대한 부호 숫자 짝짓기(순간 판단력)을 검사한 결과, 니코틴의 수면에 대한 상호관계는 알려지지 않았고, 인간의 감정이나 의식, 인식에 영향을 주는 것으로 알고있지만, 장기적은 측면에서 흡연이나 알코올은 인식능력과 무관한 것 같다. 카페인에 대한 숫자 외우기(암기력)검사 결과, 카페인은 spacial selective attention에는 특별한 영향을 주지 않지만 지각과정이나 주의 집중에 큰 효과를 주며, 인간의 의식 수행에 긍정적인 효과를 준다. 즉 카페인은 활력, 혼란, 피로상태를 변화시키고 visual analog scales에서 휴식상태에 가까운 양상을 나타낸다. 또 48시간 동안 수면을 취하지 않은 사람에게 카페인은 집중력과 장시간의 좋은 기분을 유지하게 하였다. 그러나 규칙적, 비규칙적으로 먹는 사람간에는 인지수행력의 차이를 보이지 않으며 상용자에서는 상당한 내성이 보인다. 수면패턴에 대한 숫자 더하기(순간 판단력)검사 결과, 집중력은 수면패턴에 의해서도 영향을 받고, 수면패턴이 바뀌게 되면 순간판단력을 저하시킨다. This study was performed to evaluate relationship of sleep and attention, and to control sleep effectively. We conducted a K-PES test of 40 medical students. K-PES contains eight elements, for example, simple response, selective response, color pairing, OddEven discrimination, number addition, number-symbol matching, memory, right-tapping, left tapping. Through these, we tested changes of memory, judgement, simple response. And we conducted a questionnaire survey to exclude bias. Results are as follows. As a results of number-symbol matching test, we know that sleeplessness is not complete responsible for physiologic function for humans. But, decreased sleep increases fatigue and decreases motivation, but no influence on learning new materials. So, long term sleeplessness decreases precision and responsibility. As a results of number-symbol matching test on smoking, a relationship of nicotine and sleep is not certain. A point of view in long term period, smoking and drinking is not related cognition, even if we know that those influence mood, consciousness and cognition. As a results of memory work test on caffeine, caffeine does not influence spacial selective attention, but mainly does perception, attention and consiousness process. Namely caffeine changes energetic activities, chaos, fatigue states and shows resting state in visual analog scales In sleeplessness for 48 hours, caffeine produced attention and good mood for a long time. But, in case of cognitive process no significance shows in regular or irregular diet. Regular diet shows high resistance. As a results of number addition test on sleep patterns, seep patterns influence attention, changes of sleep patterns decrease a moment judgement.

      • KCI등재후보

        Identification of Genes Modulated by High Extracellular Calcium in Coculture of Mouse Osteoblasts and Bone Marrow Cells by Oligo Chip Assay

        Kim, Hyung-Keun,Song, Mina,Jun, ji-Hae,Woo, Kyung-Mi,Kim, Gwan-Shik,Baek, Jeong-Hwa The Korean Academy of Oral Biology 2006 International Journal of Oral Biology Vol.31 No.2

        Calcium concentration in the bone resorption lacunae is high and is in the mM concentration range. Both osteoblast and osteoclast have calcium sensing receptor in the cell surface, suggesting the regulatory role of high extracellular calcium in bone merabolism. In vitro, high extracellular calcium stimulated osteoclastogenesis in coculture of mouse osteoblasts and bone marrow cells. Therefore we examined the genes that were commonly regulated by both high extracellular calcium and 1,25(OH)_(2)vitaminD_(3)(VD3) by using mouse oligo 11 K gene chip. In the presence of 10 mM[Ca^(2+)]e or 10 nM VD3, mouse calvarial osteoblasts and bone marrow cells were co-cultured for 4 days when tartrate resistant acid phosphatase-positive multinucleated cells start to appear. Of 11,000 genes examined, the genes commonly regulated both by high extracellular calcium and by VD3 were as follows; 1) the expressions of genes which were osteoclast differentiation markers or were associated with osteoclastogenesis were up-regulated both by high extracellular calcium and by VD3; trap, mmp9, car2, ctsk, ckb, atp6b2, tm7sf4, rab7, 2) several chemokine and chemokine receptor genes such as sdf1, scya2, scyb5, scya6, scya8, scya9, and ccr1 were up-regulated both by high ectracellular calcium and by VD3, 3) the genes such as mmp1b, mmp3 and c3 which possibly stimulate bone resorption by osteoclast, were commonly up-regulated, 4) the gene such as c1q and msr2 which were related with macrophage function, were commonly down-regulated, 5) the genes which possibly stimulate osteoblast differentiation and/or mineralization of extracellular matrix, were commonly down-regulated;slc8a1, admr, plod2, lox, fosb, 6) the genes which possibly suppress osteoblast differentiation and/or mineralization of extracellular matrix, were commonly up-regulated;s100a4, npr3, mme, 7) the genes such as calponin 1 and tgfbi which possibly suppress osteoblast differentiation and/or mineralization of extracellular matrix, were up-regulated by high extracelluar calcium but were down-regulated by VD3. These results suggest that in coculture condition, both high extracellular calcium and VD3 commonly induce osteoclastogenesis but suppress osteoblast differentiation/mineralization by regulating the expression of related genes.

      • The HBV DNA Amounts in Serum Have No relationship with ALT level and Hetergeneous Population Coexits in Chronic Hepatitis B Virus Infection

        Chun, Yoon-Keun,Ha, Joo-hun,Hong-Jung-Woo,Oh, Soo-Myung,Kim, Sung-Soo 경희대학교 동서의학연구소 1999 INTERNATIONAL SYMPOSIUM ON EAST-WEST MEDICINE Vol.1999 No.1

        Yoon-Keun Chun¹,Joohun Ha□Hong-Jung Woo□, Soo Myung Oh□,Sung Soo Kim□ ¹Department of Molecular Biology, College of Medicine,²Department of Surgery, college of Medicine,³Department of Internal Medicine, College of Oriental Medicine,and ⁴East-Weat Medical Reserch Institute,Kyung Hee University, Seoul, Korea. The HBV DNA Amounts in Serum Have No relationship with ALT level and Hetergeneous Population Coexits in Chronic Hepatitis B Virus Infection. Proceedings of International Symposium on East-West Medicine, Seoul. 212-230, 1999. -Hepatitis B is caused by hepadnavirus. Hepatitis B virus replicates through 3.5kb pregenomic RNA intermediate which is regulated by core promoter. Pathogenesis of hepatitis B virus has been bilieved the result of host immune response. But recently many studies have reported that high level of viral replication caused by mutation in core promoter might result in severs hepatitis. But these studies were performed in vitro, not in vivo. So there is yet debate about which factor, viral of host factor, is more important in pathogenesis of hepatitis B virus. So we measured real viral replication level in 204 chronic hepatitis B patients by quantifying HBV DNA from sera by our novel PCR-based more sensitive method, and compared these results with ALT level measured from same sera, which indicates liver cell damage. Surprisingly there are no significant correlation between HBV DNA quantity and ALT level. Then we cloned core promoter region. In SSCP, we found that many viral mutants coexist in one patient. Base on SSCP result, we chose main viral core promoter type in each patients, which is thought to determine overall viral replication level in this patient. Main type of core promoter region of each 41 patients were directly sequenced. And with these we measured promoter activity by luciferase assay system and compared promoter activity with on another. We found tha there were some differences in promoter activity according to core promoter sequences. And we constructed replication-competent viral constructs with core promoter from 41 patients and Transfected these into HepG2 cell and measured HBV DNA by southern blot. There were also differences in HBV DNA quantity according to core promoter sequences. On these all results we investigated correlation between the effect of HBV core promoter on viral replication in vitro and HBN DNA quantity, ALT level from sera of each patients. We found there is no significant correlation among them. As a result, we concluded that in determining severity chronic hepatitis B patients, host factors of each patient is more important rather than replicative activity of virus itself.

      • SCOPUSKCI등재

        TEOS 솔 침전공정에서 SiO2 과포화 농도 및 입자 크기에 미치는 반응조건 영향

        김경수,김선근,김우식,김성수,김준경 한국화학공학회 2000 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.38 No.6

        본 연구에서는 솔 침전공정에서 TEOS(Tetraethylorthosilicate) 반응물을 이용하여 실리카 분말 합성시에 TEOS 농도, 물농도, 반응물 주입속도, 교반속도 등의 반응조건이 실리카 과포화 농도 및 입자크기에 미치는 영향에 대해 연구하였다. TEOS 반응물과 물 농도가 증가할수록 입자유도시간은 짧아졌으며 입자유도시점에서의 과포화 농도는 감소하였다. 그러나, 반응물 주입속도가 입자유도시간과 입자유도시점에서의 과포화 농도에 미치는 영향은 서로 상반되었다. 즉, 반응물 주입속도의 증가에 따라 입자유도시간은 감소하였으나 입자유도시점에서의 과포화 농도는 증가하였다. 반응조건에 따라 서로 다른 과포화 농도에서 입자가 유도되는 것은 입자의 형성에 있어서 과포화도 이외의 용액의 조건에도 영향을 준다는 것을 의미하는 것이다. 한편, 교반속도는 입자유도시간과 유도시점에서의 과포화 농도는 거의 영향을 주지 않았다. 이것은 솔 침전공정에서 반응물 혼합시간이 충분히 짧아 실리카 생성에 있어서 반응속도가 입자유도 및 과포화 농도 결정에 가장 크게 영향을 미쳤기 때문이다. 반응조건에 따른 가수분해 및 축합 반응속도를 Kim등[15]이 제시한 식을 이용하여 예측하였으며 이 결과는 본 실험에서 측정한 입자유도시간의 함수로도 매우 잘 묘사될 수 있었다. 또한, 반응조건에 따라 합성된 최종입자의 크기 변화도 입자유도시간의 함수로 훌륭히 묘사될 수 있음을 보여 주었다. In a single feed semi batch reactor effects of reaction conditions, such as TEOS and water concentrations, react feed flow rate and agitation speed, on the silica supersaturation and particle size synthesized in sol precipitation were investigated. As the TEOS and water concentrations increased, the particle induction time and the supersaturation at the particle induction point were reduced. However, the dependencies of the particle induction time and supersaturation at the particle induction point on the reactant flow rate were opposite to each other. That was, the particle induction tune decreased with increase in the reactant flow rate but the supersaturation at the particle induction point increased. The fact that the supersaturation level to induce the particle was varied with the reaction condition implied that the solution condition determined by the reaction condition as well as the supersaturation level was important to the particle induction. Meanwhile, the particle induction time and supersaturation at the particle induction point were little influenced by the agitation speed in the reactor. This result was due to the micromixing time being short enough in comparison to the reaction time of TEOS. Thus, the particle induction time and supersaturation at the particle induction point was predominantly determined by the reaction time rather than the micromixing time of TEOS. The reaction rate constants of TEOS hydroysis and condensation, which was predicted with Kim et al.'s equations [15] at the reaction conditions was described as a function of the particle induction time. In addition, the particle size synthesized at the reaction conditions was able to be well fitted as a function of the particle induction time.

      • 객체 지향 제품데이터 관리시스템의 동적 모델링

        김종화,박우근 건국대학교 산업기술연구원 2000 건국기술연구논문지 Vol.25 No.-

        As the number of product variants in a company increases and the life cycles of those products decrease, an efficient management of product data has become an important issue. To cope with these situation effectively, the object-oriented approaches have been applied as an alternative to the traditional approaches. In this paper, conceptual modeling of an object-oriented product data management system is suggested by applying Rumbaugh's Object-Modeling Technique. In modeling the system, we focus on the dynamic modeling for the efficient management of frequent changes in engineering data and functional modeling to represent data flow between the objects identified.

      • 지문과 정신분열증

        우숙희,정국동,최송표,조근자,양은진,김수일,박경란,이영호,김원식 충남대학교 의과대학 지역사회의학연구소 1998 충남의대잡지 Vol.25 No.1

        Fingerprint patterns of 333 schizophreniacs who met with the diagnostic criterias of International Pilot Study of Schizophrenia except items associated with chronicity in exclusion criteria were studied, and the following results were obtained. 1. The frequency distribution of the fingerprint patterns in the 333 schizophreniacs was ulnar loop, whorl, twinned loop, arch, radial loop in order in both control and schizophrenia groups. 2. Finger ridge counts of both sexes were decreased significantly in schizophrenia group. 3. Dissociation of fingerprint pattern in the schizophrenia group was 51.1%, which was far greater than 6.25% of control group. Number of dissociation was greatest in the thumb, followed by index, middle, ring, and little finger in order. According to the above results, it is considered that both the number of finger ridges and degree of dissociation of fingerprint patterns were closely related with schizophrenia. Analysis of fingerprints and palmprints with the aid of chromosomal analysis would contribute the early diagnosis and prevention of schizophrenia.

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