Controlled infiltration profile of SiC coating layer on graphite by Si vapor deposition reaction

Kuk-Jin Hwang,Si-Young Bae,Kyoung-Ho Kim,Yoon-Cheol Lee,Jung-Tae Hwang,Heesoo Lee,Seong Min Jeong,Myung-Hyun Lee 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.2

SiC-coated graphite was successfully fabricated at different temperatures (1300-1600 oC) through a silicon vapor depositionreaction (Si-VDR) process. Si powder was used for the Si source of the SiC coating layers. When Si powder was evaporatedat high temperature near the melting point of bulk Si, Si gases are moved and changed into Si liquid at the surface of thegraphite. The high-temperature process facilitated the formation of SiC coating layers on the graphite. The microstructural,mechanical, and thermal oxidation properties of the coated graphite were investigated.

국내 혈액질환 환자에서 침습성 아스페르길루스증의 구제치료로서 Voriconazole의 효과와 안전성

권재철,김시현,최수미,최재기,이동건,박선희,최정현,유진홍,신완식 대한감염학회 2010 감염과 화학요법 Vol.42 No.1

Background: Invasive aspergillosis (IA) is associated with significant morbidity and mortality in patients with hematologic malignancies. We investigated the efficacy and safety of voriconazole (VCZ) when used as salvage therapy for IA in Korean adults with hematologic malignancies who had not responded to prior antifungal therapy. Materials and Methods: We retrospectively reviewed data, collected from January 2007 to October 2008, from patients with proven or probable cases of IA. All were probable IA cases, except for one proven case. All cases were refractory or intolerant to antifungal therapy prior to administration of VCZ. Efficacy and safety were assessed in patients treated with VCZ for more than 3 days and for more than one dose, respectively. A favorable response [complete (CR) or partial (PR)] was defined by significant improvement of all clinical symptoms, signs, and radiologic abnormalities. Results: Fifty patients who met the inclusion criteria were enrolled. There were 27 male and 23 female patients with mean age of 44.4 years (range, 15-65 years). Underlying diseases were acute leukemia (35 cases), chronic myelogenous leukemia (4 cases), myelodysplastic syndrome (3 cases), lymphoma (3 cases) and other hematologic diseases (5 cases). Twenty-two patients had received chemotherapy and 13 patients had undergone hematopoietic stem cell transplantation. The lung was the main infection site (94%) followed by the sinus (6%). Amphotericin B deoxycholate alone was the most frequent previous antifungal therapy. The mean duration of antifungal therapy prior to VCZ therapy was 13.9±8.8 days (2-44 days). The median duration of VCZ therapy was 19 days (interquartile range, 49 days). Sixteen patients (32.0%) showed favorable responses (CR:PR=8:8) at the end of VCZ therapy. The numbers of patients with stable disease, progression and death were, 6 (12%), 6 (12%) and 22 (44%) respectively. Most of those with unfavorable responses had relapsed underlying malignancies or refractory graft versus host diseases. Twelve patients developed drug-related adverse events but only one patient stopped VCZ treatment prematurely. Conclusions: VCZ demonstrated an acceptable level of toxicity in patients with hematologic malignancies but further studies are required to prove its efficacy as salvage therapy.

조혈모세포이식 환자에서 침습성 진균 감염에 대한 Micafungin의 예방 효과 및 안전성

김시현,이동건,최수미,권재철,박선희,최정현,유진홍,이성은,조병식,김유진,이석,김희제,민창기,조석구,김동욱,이종욱,민우성,박종원 대한감염학회 2010 감염과 화학요법 Vol.42 No.3

Background: Micafungin, a potent inhibitor of 1,3-β-D-glucan synthase, is a novel antifungal agent of the echinocandin class. In vitro study showed that micafungin was effective against Aspergillus species as well as Candida species, but clinical data on the prophylactic efficacy against invasive fungal infections (IFIs) other than candidiasis are still lacking. Materials and Methods: We identified 60 consecutive adult hematopoietic stem cell transplantation (HSCT) recipients who received at least 3 doses of micafungin during neutropenic period. Micafungin was started as an alternative in patients who were intolerant or had adverse events (AEs) to primary prophylactic antifungal agents. We retrospectively reviewed the medical records and analyzed the efficacy and safety of micafungin for prophylaxis against IFIs. Results: The patients either had autologous (n=9) or allogeneic (n=51: 1 syngeneic, 24 sibling, 26 unrelated donor) HSCT. Itraconazole oral solution (n=58) was the most frequently used first line antifungal agent for prophylaxis and was administered for median 11 days. The most frequent cause of switch to micafungin was vomiting (n=42). The duration of neutropenia and micafungin administration was median 13 and 12 days, respectively. A successful outcome was achieved in 45 (75%) patients. Empirical antifungal therapy was initiated in 13 (22%) patients. There were 2 cases (3.3%) of breakthrough fungal infections which comprised a probable invasive pulmonary aspergillosis and a possible invasive fungal sinusitis. There was no case of invasive candidiasis. A total of 53 (88%) patients experienced at least one AE regardless of causality during micafungin administration. The most frequent AEs were hypokalemia, vomiting, diarrhea, and elevated serum aspartate aminotransferase or alanine aminotransferase. Among the aforementioned AEs, only 1 case of diarrhea could be classified as a probable relation with micafungin when causality was assessed. There was no AEs that caused discontinuation of micafungin. Conclusions: Micafungin seems to be a safe and effective agent for prophylaxis of IFIs including aspergillosis as well as candidiasis in HSCT recipients. However, further large, prospective, and randomized comparative studies are warranted for aspergillosis.

일부 소규모 시계조립 사업장의 상지 누적외상성장애의 유병률

장은철,김현주,권영준,박시복,이수진,송재철 大韓産業醫學會 2000 대한직업환경의학회지 Vol.12 No.4

목적 : 단순 반복작업을 하는 시계조립 사업장 근로자를 대상으로 상지 누적외상성장애의 자각증상 유병률과 상지 누적외상성장애 유병률을 파악하고자 하였다. 방 법 : 인구학적 특성, 상지의 자각증상, 사회심리적 요인은 자가 설문지법으로, 인간공학적 특성은 점검표를 이용한 면담법으로 조사하였다. 상지의 자각증상 조사와 사회심리적 요인은 각각, N10SH (1993) 설문지와 Karasek(1979)의 Job strain model을 번역하여 조사하였다. 상지 누적외상성장애 판정은 의사가 작업 현장에서 직접 환자 면담과 이학적 검사를 수행한 후, 연구에서 규정한 증례정의에 의해 수행하였다. 수집된 자료는 x2 teat와 exact test로 단별량 분석을 하였고, 이중 의미있는 변수와 위험 인자로 알려진 변수들로 다중 로지스틱 회귀분석을 시행하였다. 결 과 : 대상자들의 자각증상 유병률은 54.2 %였고, 부위별로는 목 34.9 %, 손/손목 31.3 %, 어깨 30.1 %, 팔/팔꿈치 18.0 %순이었다. 상지 누적외상성장애의 유병률은 45.8 %였고, 근막동통증후군이 26명으로 가장 많았고, De Quervain씨 병 8명, 수부/전완부의 건염 및 건활막영 8명, 수근관 증후군 5명, 이두건염 5명, 척골 신경병증 5명, 내상과 염 4명, 외상과염 2명, 경추 디스크 질환 2명, 흥곽 출구 증후군 1명순으로 나타났다. 단변량 분석시 자각증상 유병률은 작업부서 중 완성 부에서, 상지 누적외상성장애 유병률은 여자와 완성 부에서 통계학적으로 유의하게 높았다. 다중 로지스틱 회귀분석 결과 완성부와 근무긴장도가 높은 군이 상지 누적외상 성장애와 통계학적으로 유의한 결과를 보였다. 결 론 : 이 연구에서 상지 누적외상성장애 유병률은 45.8 %으로서 저강도의 단순 반복작업을 하는 시계조립 사업장 근로자에서도 누적외상성장애의 위험이 있는 것으로 생각된다. 또한, 사회심리적 요인과 작업 부서별 공정 및 환경이 유병률에 영향을 미치는 주요 요인으로 생각되며, 향후 이들에 관한 다양한 연구가 진행되어야 할 것이다. 산업보건 현장에서는 시계조립 사업장과 같이 저 강도의 단순 반복작업을 위주로 하는 사업장에 대한 지속적인 관심과 각 사업장별 위험요인을 파악하여 적절한 예방 및 관리 대책을 세워야 할 것이다. Objectives : The prevalence of cumulative trauma disorders of upper extremities mons watch assembly workers in small-scaled industry was studied. Methods. In 83 workers at five watch assembly factories, symptoms and psychosocial questionnaire, ergonomic Interview, physical examination were conducted. Results : Prevalence of self-reported symptoms was 54.2% and neck 34.9%, wrist/hand 31.3%, shoulder 30.1%, elbow/arm 18.0% by anatomical site. Prevalence of cumulative trauma disorders was 45.8%. Most common disease was myofascial pain syndrome (31.3%). The other diseases were De Quervain disease (9.6%), tenosynovitis/tendinitis at wrist/hand (9.6%), bicipital tendinitis(6.0%), fat. epicondylitis(4.8%), meIn. epicondylitis(2.4%), and cervical disc disease(2.4%). As result of ergonomic interview, repetitiveness was 79(98.8%). There were no differences in the prevalence of self-reported symptoms and cumulative trauma disorders for age, sex, marital status, duration of work In the study, The significant factors of cumulative trauma disorders were occupational task and psychosocial stress in the study. The prevalence of cumulative trauma disorders in high strain group was hlgher (68.4%) than other three groups. The prevalence of self-reported symptoms and cumulative trauma disorders in assembly task was higher (70.0%, 64.0%) than other two tasks. Conclusions : Prevalence of self-reported symptoms was 54.2%, prevalence of cumulative trauma disorders was 45.8% in watch assembly workers. In this study, factor related to self-reported symptoms was occupational task and factors relaxed to cumulative trauma disorders were occupational task and psychosocial stress. This results suggest that differences of ergonomics and environment in occupational task cause differences of prevalence of self-reported symptoms and cumulatlve trauma disorders.

VDT 작업 여성근로자의 근골격계 자각증상과 다면적인성검사(MMPI)의 임상척도들과의 연관성

기모란,이수진,송재철,박시복,이원영,권영준,남정현 大韓産業醫學會 1998 대한직업환경의학회지 Vol.10 No.4

A study was conducted to assess the association between musculoskeletal subjective symptoms and the MMPI(Minnesota Multiphasic Personality Inventory) profile. The study subjects were 539 female operators of telecommunication company in Seoul, and were interviewed with subjective symptom questionnaire and MMPI. Results were as follows 1. 77.5% of the study subjects complained subjective symptoms on the shoulder, 73.8% on the neck, 71.8% on the lower back, 67.5% on the arm, 67.2% on the hand, 39.8% on the elbow, respectively. According to NIOSH symptom criteria, 63% complained on the shoulder, 57.4%, 54.6% on the lower back, 53.2% on the hand, 45.9% on the arm, 29.8% on the elbow, respectively. 2. Among the MMPI clinical scales, Hs(Hypochondriasis), Hy(Hystria) and Dep(Depresson) scales showed significant differences according to the numbers of subjective symptom(NIOSH criteria), VAS(Visual Analogue Scale), and the experience of sick leave(each by ANOVA, p<0.05). 3. The association between the numbers of subjective symtom site for NIOSH symtom criteria, the personal history of sick leave and MMPI profile that has more than 70 points in anything of Hs, Dep and Hy scales was showed significantly(each by x²-test, p<0.05).

수술실 오염도감소를 위한 수술실공조시스템에 대한 연구

김천숙,박은정,강규식,김지은,안기량,권진형,유시현,주영철,권순정 순천향의학연구소 2004 Journal of Soonchunhyang Medical Science Vol.10 No.1

Background: The OR(operating room) should provide an optimum environment that is safe for the patient and the working personnel. The air ventilation system of OR has been studied to decrease the contamination of air. We investigated the flow and contamination of the air in OR at our hospital. Method: Cultures in OR were made and the number of bacteria and fungi were calculated. A two-dimensional model for the cross-section of an operation room is developed for the CFD (computational fluid dynamics) analysis. The characteristics of air flow in the empty operation room and in the occupied operation room are calculated by using a CFD program. Results: The current air ventilation system of our hospital does not deliver the clean air to the operating site efficiently in occupied OR. Conclusions: We suggested a new location of air ventilation system which improves air venting with little increase of the cost of equipment.

Stress-relieved Si anode on a porous Cu current collector for high-performance lithium-ion batteries

Moon, Sang-Hyun,Kim, Si-Jin,Kim, Min-Cheol,So, Jin-Young,Lee, Ji-Eun,Shin, Yeon-Kyung,Bae, Won-Gyu,Park, Kyung-Won Elsevier 2019 Materials chemistry and physics Vol.223 No.-

<P><B>Abstract</B></P> <P>To overcome the mechanical stress generated during the cycling process in lithium-ion batteries, Si anode is fabricated on a porous Cu current collector with holes using sputtering deposition method. The porous Cu/Si shows superior high-rate and cycling performance in lithium-ion batteries compared to the Si anode on the flat Cu. The excellent high-rate performance and stable cyclability of the porous Cu/Si can be predominantly attributed to the efficient relief of the stress generated by the volumetric expansion of the Si anode on the porous Cu current collector.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Si anode for LIBs was fabricated on a porous Cu current collector having holes. </LI> <LI> The porous Cu/Si showed the superior high-rate and cycling performance. </LI> <LI> The excellent performance of the porous Cu/Si can be due to the relief of the stress. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Real-Time Nucleic Acid Sequence-Based Amplification to Predict the Clinical Outcome of Invasive Aspergillosis

Kim, Si-Hyun,Park, Chulmin,Kwon, Eun-Young,Shin, Na-Young,Kwon, Jae-Cheol,Park, Sun Hee,Choi, Su-Mi,Lee, Dong-Gun,Choi, Jung-Hyun,Yoo, Jin-Hong The Korean Academy of Medical Sciences 2012 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.27 No.1

<P>Monitoring the response to therapy for invasive aspergillosis (IA) is essential for the management of patients with hematologic diseases. We evaluated the correlation between the outcome of real-time nucleic acid sequence-based amplification (RTi-NASBA) for <I>Aspergillus</I> 18S rRNA and the clinical outcome of IA. A total of 157 serum samples from 29 patients with IA were tested for RTi-NASBA. The treatment response and mortality were compared with the NASBA outcome (whether the NASBA value was converted to negative or not) at 12 weeks after the start of antifungal therapy. At 12 weeks, there was a moderate correlation between the treatment failure and persistently positive NASBA (κ = 0.482; <I>P</I> = 0.019). Deaths attributable to IA were more prevalent in patients without negative conversion of NASBA than in those with negative conversion (50% vs 5%; <I>P</I> = 0.013). Significant factors of treatment failure at 12 weeks were the status of hematologic disease (nonremission; <I>P</I> = 0.041) and the NASBA outcome (failure of negative conversion; <I>P</I> = 0.024). Survival was significantly better in patients with negative conversion of NASBA than those with persistently positive values (<I>P</I> = 0.036). This study suggests that the serial monitoring of RTi-NASBA could be useful for prediction of the clinical outcome in hematologic patients with IA.</P>

Progress and perspectives of metal-ion-substituted hydroxyapatite for bone tissue engineering: comparison with hydroxyapatite

Kim Si Hyun,Park Cheol Hyun,Heo Jun Hyuk,이정헌 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.3

Hydroxyapatite (HA) is one of the most common bioceramics and is abundant in human bones. HA is composed of calcium phosphate, which is prevalent in biomedical processes, particularly bone formation, osteogenesis, and angiogenesis. As HA is one of the core materials that makes up the human body, there has been considerable research on methods of synthesizing HA while changing its properties by substituting various types of metal ions. In particular, previous studies have intensively investigated the size, crystallinities, and morphologies generated using various synthesis methods to change the character- istics of HA by substituting different metal ions. This review summarizes the findings of these studies on HA, including findings on the characteristics of HA in natural bone, methods of synthesizing HA, and findings on metal-ion-substituted HA. Furthermore, the characteristics and applications of HA that were investigated in previous studies are summarized, and the latest trends and perspectives on the future of the field are also presented.

PVC를 원료로 탄소코팅한 Li₄Ti<SUB>5</SUB>O<SUB>12</SUB>의 합성 및 전기화학적 특성

현시철(Si-Cheol Hyun),나병기(Byung-Ki Na) 한국청정기술학회 2018 청정기술 Vol.24 No.1

리튬이온전지의 음극활물질로 사용되는 Li₄Ti5O12를 건식 볼밀법으로 합성하였고, Li₄Ti5O12의 전기화학적 특성을 향상시키기 위하여 탄소소재인 polyvinyl chloride (PVC)를 첨가하였다. PVC는 Li4Ti5O12를 합성하고 난 후에 첨가하였을 때 스피넬구조를 갖는 물질이 잘 합성되었음을 X-ray diffraction (XRD) 실험으로 확인하였다. 합성하기 전에 탄소재를 첨가하여 열처리를 한 경우에는 탄소재가 미량 첨가되더라도 다른 결정구조의 물질이 합성되는 것을 확인할 수 있었다. 탄소재를 첨가하지 않은 Li₄Ti5O12의 경우 전기전도도 값이 약 10 μS m<SUP>-1</SUP>으로 부도체에 가까운 매우 작은 값을 보였다. 탄소를 첨가함에 따라서 전기전도도가 크게 향상되었으며, 압력을 증가시킬 경우에 최대 10,000배 이상 증가되었다. Electrochemical impedance spectroscopy (EIS) 분석결과 탄소를 첨가할 경우 저항에 해당하는 반원의 크기가 감소하였으며, 이는 전극내의 저항이 감소하였음을 보여준다. Cyclic voltammetry (CV) 분석에 의하면 탄소를 첨가할 경우에 산화피크와 환원피크의 전위차가 줄어들었으며, 이는 리튬이온의 삽입과 탈리의 속도가 증가하였음을 의미한다. PVC를 9.5 wt% 첨가한 물질의 경우, 0.2 C-rate에서 180 mA h g<SUP>-1</SUP>, 0.5 C-rate에서 165 mA h g<SUP>-1</SUP>, 5C-rate에서 95.8 mA h g<SUP>-1</SUP>의 용량을 나타냄으로써 우수한 출력 특성을 보여주었다. In this study, Li₄Ti5O12 anode materials for lithium ion battery were synthesized by dry ball-mill method. Polyvinyl chloride (PVC) as a carbon source was added to improve electrochemical properties. When the PVC was added after Li₄Ti5O12 formation, the spinel structure was well synthesized and it was confirmed by X-ray diffraction (XRD) experiments. When the carbon material was added before the synthesis and the heat treatment was performed, it was confirmed that a material having a different crystal structure was synthesized even when a small amount of carbon material was added. In the case of Li₄Ti5O12 without the carbon material, the electrical conductivity value was about 10 μS m<SUP>-1</SUP>, which was very small and similar to that of the nonconductor. As the carbon was added, the electrical conductivity was greatly improved and increased up to 10,000 times. Electrochemical impedance spectroscopy (EIS) analysis showed that the size of semicircle corresponding to the resistance decreased with the carbon addition. This indicates that the resistance inside the electrode is reduced. According to the Cyclic voltammetry (CV) analysis, the potential difference between the oxidation peak and the reduction peak was reduced with carbon addition. This means that the rate of lithium ion insertion and deinsertion was increased. Li₄Ti5O12 with 9.5 wt% PVC added sample showed the best properties in rate capabilities of 180 mA h g<SUP>-1</SUP> at 0.2 C-rate, 165 mA h g<SUP>-1</SUP> at 0.5 C-rate, and 95.8 mA h g<SUP>-1</SUP> at 5 C-rate.