브라켓 각도 변화에 따른 세라믹 브라켓의 마찰력 측정

차정열,김경석,김동춘,황충주 대한치과교정학회 2006 대한치과교정학회지 Vol.36 No.2

최근 사용되고 있는 세라믹 브라켓의 마찰력을 측정하고 비교하고자 실험군으로 3종의 세라믹 브라켓(Crystaline V(^®), Tomy, Tokyo, Japan; Clarity^(®), 3M Unitek, CA; Inspire^(®), Ormco, CA)을 사용하였으며 대조군으로 컴퍼짓 레진 브라켓(Spirit^(®), Ormco, CA)과 메탈브라켓(Kosaka^(®), Tomy, Tokyo, Japan)을 사용하였다. 활주 시 마찰력은 4개의 브라켓-교정선 경사(0°, 5°, 10°, 15°)에서 각각 측정되었으며 두 종의 교정선 [1. 스테인레스 스틸(Stainless Steel, SDS Ormco, Glendora, CA), 2. 베타-타이타늄(TMA, SDS Ormco, Glendora, CA)]이 사용되었다. 22mil 브라켓을 만능시험기기에 부착한 후 .021 × .025 크기의 교정선에 고무결찰한 후 34℃의 건조상태에서 5mm/min 속도로 교정선을 활주시켰다. TMA 교정선은 스테인레스 스틸 교정선보다 높은 마찰력을 발생시켰으며 모든 브라켓 호선과의 조합에서 브라켓-교정신의 각도가 증가함에 따라 정적, 동적 마찰력이 증가하였다. 0°~5° 구간에서 마찰력의 크기는 스테인레스 스틸 교정선과 레진 브라켓 조합이 가장 낮게 측정되었으며 다음으로 Crystaline V, 금속 브라켓, Clarity, Inspire의 순으로 나타났다. TMA 교정선에서는 Crystaline V와의 조합이 가장 낮은 마찰력을, 다음으로 컴퍼짓 브라켓, Clarity, 금속 브라켓, Inspire 순으로 나타났다. 5° 이상에서 마찰력이 급격하게 증가하였으며 스테인레스 스틸 교정선에서 레진 브라켓, Clarity, Crystaline V, 금속 브라켓, Inspire순으로 나타났다. TMA 교정선에서는 레진 브라켓, Crystaline V, Clarity, Inspire, 금속 브라켓 순으로 나타났다. 이때 호선 브라켓 조합에 대한 마찰력은 일반적으로 증가하였으나 마찰력 증가율의 차이로 인해 그룹간 마찰력의 순위가 서로 뒤바뀌는 경우가 관찰되었다. 실리카-삽입 세라믹 브라켓은 기존의 세라믹 브라켓보다 낮은 마찰력을 보여줄 뿐 아니라 브라켓-교정선의 경사도의 증가에서도 비교적 낮은 마찰력 증가율을 나타내어 세라믹 브라켓의 높은 마찰력을 감소시키는데 큰 역할을 할수 있다고 생각된다. The purpose of this study was to measure and compare the level of frictional resistance generated from three currently used ceramic brackets; 1, Crystaline V^(®), Tomy International Inc., Tokyo, Japan; 2, Clarity^(®), 3M Unitek, Monrovia, CA, USA; 3, Inspire^(®), Ormco, Orange, CA, USA; with composite resin brackets, Spirit^(®), Ormco, Orange, CA, USA; and conventional stainless steel brackets Kosaka^(®), Tomy International Inc., Tokyo, Japan used as controls. In this experiment, the resistance to sliding was studied as a function of four angulations (0°, 5°, 10°, and 15°) using 2 different orthodontic wire alloys: stainless steel (stainless steel, SDS Ormco, Orange, CA, USA), and beta-titanium (TMA, SDS Ormco, Orange, CA, USA). After mounting the 22 mil brackets to the fixture and .019 × .025 wires ligated with elastic ligatures, the arch wires were slid through the brackets as 5 mm/min in the dry state at  34℃. Silica-insert ceramic brackets generated a significantly lower frictional force than did other ceramic brackets, similar to that of stainless steel brackets. Beta-titanium archwires had higher frictional resistance than did stainless steel, and all the brackets showed higher static and kinetic frictional force as the angulations increased. When the angulation exceeded 5°, the active configuration emerged and frictional force quickly increased by 2.5 to 4.5-fold. The order of frictional force of the different wire-bracket couples transposed as the angle increased. The silica-insert ceramic bracket is a valuable alternative to conventional stainless steel brackets for patients with esthetic demands.

DEVELOPMENT OF A SUPERCRITICAL CO₂ BRAYTON ENERGY CONVERSION SYSTEM COUPLED WITH A SODIUM COOLED FAST REACTOR

Cha, Jae-Eun,Lee, Tae-Ho,Eoh, Jae-Hyuk,Seong, Sung-Hwan,Kim, Seong-O,Kim, Dong-Eok,Kim, Moo-Hwan,Kim, Tae-Woo,Suh, Kyun-Yul Korean Nuclear Society 2009 Nuclear Engineering and Technology Vol.41 No.8

Systematic research has been conducted by KAERI to develop a supercritical carbon dioxide Brayton cycle energy conversion system coupled with a sodium cooled fast reactor. For the development of the supercritical $CO_2$ Brayton cycle ECS, KAERI researched four major fields, separately. For the system development, computer codes were developed to design and analyze the supercritical $CO_2$ Brayton cycle ECS coupled with the KALIMER-600. Computer codes were developed to design and analyze the performance of the major components such as the turbomachinery and the high compactness PCHE heat exchanger. Three dimensional flow analysis was conducted to evaluate their performance. A new configuration for a PCHE heat exchanger was developed by using flow analysis, which showed a very small pressure loss compared with a previous PCHE while maintaining its heat transfer rate. Transient characteristics for the supercritical $CO_2$ Brayton cycle coupled with KALIMER-600 were also analyzed using the developed computer codes. A Na-$CO_2$ pressure boundary failure accident was analyzed with a computer code that included a developed model for the Na-$CO_2$ chemical reaction phenomena. The MMS-LMR code was developed to analyze the system transient and control logic. On the basis of the code, the system behavior was analyzed when a turbine load was changed. This paper contains the current research overview of the supercritical $CO_2$ Brayton cycle coupled to the KALIMER-600 as an alternative energy conversion system.

High-resolution X-ray Imaging Based on Pixel-structured CsI:Tl Scintillating Screens for Indirect X-ray Image Sensors

Cha, Bo Kyung,Lee, Dong Hoon,Kim, Bonghoe,Seo, Chang-Woo,Jeon, Sungchae,Huh, Young,Kim, Jong Yul,Cho, Gyuseong,Kim, Youngju Korean Physical Society 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.6

Correlation Between Sorangium cellulosum Subgroups and Their Potential for Secondary Metabolite Production

( Cha Yul Lee ),( Dong Ju An ),( Han Bit Lee ),( Kyung Yun Cho ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.3

Phylogenetic analysis of the groEL1 and xynB1 gene sequences from Sorangium cellulosum strains isolated in Korea previously revealed the existence of at least 5 subgroups (A-E). In the present study, we used sequence analysis of polymerase chain reaction-amplified biosynthetic genes of strains from the 5 subgroups to indicate correlations between S. cellulosum subgroups and their secondary metabolic gene categories. We detected putative biosynthetic genes for disorazol, epothilone, ambruticin, and soraphen in group A, group C, group D, and group E strains, respectively. With the exception of KYC3204, culture extracts from group A, group B, and group C strains exhibited no noticeable antimicrobial inhibitory activities. By contrast, culture extracts from group D strains inhibited the growth of Candida albicans, whereas culture extracts from group E strains inhibited the growth of C. albicans and Staphylococcus aureus. High performance liquid chromatography analysis of the culture extracts from the strains of each subgroup revealed unique peak patterns. Our findings indicate the existence of at least 5 subgroups of S. cellulosum strains, each of which has the potential to produce a unique set of secondary metabolites.

Research Articles : Microwave Dehydrogenation of Ethane to Ethylene

( Dong Kook Kim ),( Chang Yul Cha ),( Woo Tae Lee ),( Jong Huy Kim ) 한국공업화학회 2001 Journal of Industrial and Engineering Chemistry Vol.7 No.6

전기밥솥으로 인한 유아수부 화상의 임상적 고찰

차상훈,조용근,임동훈,안성열,황귀환 大韓成形外科學會 1993 Archives of Plastic Surgery Vol.20 No.2

We noticed a high incidence of infants burned by steam through the nozzle of the electric rice cooker. The infants were apparently attracted to the cooker by the high pitched sound made by escaping steam during the first minutes after the rice cooked. These burns seemed to manifest more uniform features than the usual child burns such as scalding and flame burns. During the past three and one half years we have studied 86 cases of these burn patients : I. e. burn patterns, environmental background of the family, treatment procedures, various hand deformities, and the timing of surgical intervention. Most of the patients ranged from 8 to 12 month old infants who were in the pediatric developmental stage of being able to creep and/or stand up by holding onto objects. The infants in this stage were attempting to catch the hot, hissing steam and suffered from third degree burns on the hand. The majority of burns were on the volar side of the hand. The unilateral hand was primarily involved. The predilection site was the index finger in one finger burns, and the index and middle finger in multiple finger burns. One finger was involved in 39.3% of all the patients. Cicatrical syndactyly was noted in 18 cases(21.2%) mostly in the second interdigital web. Contracture was also seen. In one-finger burns the PIP joint area was primarily involved(52.6%) : while in two finger burns the MP joint area suffered followed by syndactyly due to scarring. The children at greatest risk were those with less educated mothers, living in a rented traditional Korean home in one or two rooms, whose first child was under 1 year old. The optimal timing of the reconstruction of the scar contracture in the infant was at least 6 months after the burn injury when the scar tissue activity settles down. Earlier surgical intervention will cause post operative recontracture. The donor site for the skin graft were selected in the groin area and non-weight bearing portion of the sole, depending upon graft size needed. For prevention it is necessary that the parents and society learn to recognize the situations under which these infant burns occur.

Poly (DL - lactide - co - glycolide) 공중합체의 합성과 그 응용 (7)

이동병,차월석,박영훈,김명렬,나재운 한국공업화학회 1998 응용화학 Vol.2 No.2

Poly(_(DL)-lactide-co-glycolice)(70:30) was synthesized from _(DL)-lactic acid and glycolic acid and The copolymers was made to micelles containing clonazepam for drug delivery system. The release experiments of the drug from micelles were operated at pH 7.4 phosphate buffer solution 37.0±0.05℃ and these results were as follows. The linearly-releasing time ranges of the drug from micelles prepared with the copolymers/drug weight ratio of 20:40, 20:20, and 40:20 (㎎ ) were 55, 45, and 33 days, respectively. So the linearly-releasing time of drug showed the order of micelles20/40 $gt; micelles20/20) micelles40/20. In short, the formulation allows polymeric micelles to suppress the burst effect of the drug release mechanism, which led to the controlled release pattern and the possibility of DDS for veinous injection.

둥굴레(Polygonatum odoratum Ohwi) 수확기 미생물 분포 조사

강동완(Dong-Wan Kang),정은호(Eun-Ho Jeong),김만배(Man-Bae Kim),조용조(Yong-Cho Cho),신현열(Hyun-Yul Shin),김영국(Young-Guk Kim),차선우(Seon-Woo Cha),배성문(Sung-Mun Bae) 한국약용작물학회 2013 한국약용작물학회 학술대회논문집 Vol.2013 No.2

Effects of recycling on the biomechanical characteristics of retrieved orthodontic miniscrews

Soon-Dong Yun,Sung-Hwan Choi,Jung-Yul Cha,Hyung-Seog Yu,Kwang-Mahn Kim,Jin Kim,Chung-Ju Hwang 대한치과교정학회 2017 대한치과교정학회지 Vol.47 No.4

Objective: The aim of this study was to compare recycled and unused orthodontic miniscrews to determine the feasibility of reuse. The comparisons included both miniscrews with machined surfaces (MS), and those with etched surfaces (ES). Methods: Retrieved MS and ES were further divided into three subgroups according to the assigned recycling procedure: group A, air-water spray; group B, mechanical cleaning; and group C, mechanical and chemical cleaning. Unused screws were used as controls. Scanning electron microscopy, energy-dispersive X-ray spectrometry, insertion time and maximum insertion torque measurements in artificial bone, and biological responses in the form of periotest values (PTV), bone–implant contact ratio (BIC), and bone volume ratio (BV) were assessed. Results: Morphological changes after recycling mainly occurred at the screw tip, and the cortical bone penetration success rate of recycled screws was lower than that of unused screws. Retrieved ES needed more thorough cleaning than retrieved MS to produce a surface composition similar to that of unused screws. There were no significant differences in PTV or BIC between recycled and unused screws, while the BV of the former was significantly lower than that of the latter (p < 0.05). Conclusions: These results indicate that reuse of recycled orthodontic miniscrews may not be feasible from the biomechanical aspect.

항갑상선 항체를 동반한 조기난소부전 1예

최동희,한세열,윤태기,차광열,남윤성 대한폐경학회 1998 대한폐경학회지 Vol.4 No.2

Premature ovarian failure is a condition causing amenorrhea, hypoestrogenism, and elevated gonadotropins in women younger than 40 years. Although chromosomal and genetic abnormalities, enzymatic defects and iatrogenic agents, including cytotoxic drugs, pelvic irradiation and ovariectomy, have been cited as causes of premature ovarian failure, the most common cause is autoimmuity. Circulating antibodies to ovarian tissue have been demonstrated in the sera of patients with premature ovarian failure. In several studies 18-30% of patients with premature ovarian failure had associated autoimmune disorders including Hashimoto's thyroiditis, Grave's disease, Addisons disease, myasthenia gravis, hyperparathyroidism. Pernicious anemia, and mucocutaneous candidiasis. These patients have been grouped by the therm polyglandular syndrome. All patients in the series had a 46,XX chromosome complement and several patients, on ovarian biopsy, had evidence of lymphocytic infiltration of the ovaries. Theories regarding etiology or mechanism for autoimmunity in ovarian failure include genetic factors, antireceptor antibodies, and/or specific tissue antigens in the ovary, including the theca interna or granulosa cells. We have experienced a case of premature ovarian failure associated with antithyroid antibodies. So we report this case with a brief review of literatures.