• 소성∙가공
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• 제27권6호
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• pp.347-355
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• 2018

This study investigated the effects of the processing number of multi-axial diagonal forging (MADF) on the microstructural changes of OFC fabricated by MADF processes. The as-extruded OFC was cut to $25mm^3$ cube for the MADF processes. The MADF process consists of plane forging with a thickness reduction of 30% and diagonal forging with a diagonal forging angle of $135^{\circ}$. In order to analyze the microstructural evolutions according to the number of repetitions, 1, 2, 3 and 4 cycles of the MADF process were performed. OFC specimens were successfully deformed without surface cracking for up to 4 cycles of MADF. The grain size, average misorientation and average grain orientation spread (GOS) of MADF processed materials were analyzed using EBSD technique and their Vicker's hardness were also measured. The results showed that MADF process effectively refined the microstructure of OFC with initial average grain size of $84.2{\mu}m$. The average grain sizes of specimens MADF processed for 1, 2, 3, 4 cycles were refined to be $8.5{\mu}m$, $2.2{\mu}m$, $1.5{\mu}m$, $1.1{\mu}m$, respectively. The grain refinement seemed to be saturated when OFC was MADF processed over 2 cycles. In the case of specimens subjected to two or more cycles of MADF, the degree of decrease in average grain size was drastically reduced as the number of cycles increased due to softening phenomena such as dynamic recovery or dynamic recrystallization during processing. The degree of increase in average Vicker's hardness was also dramatically reduced as the number of cycles increased due to the same reason.

• 천문학회보
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• 제35권1호
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• pp.36.1-36.1
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• 2010

OFC (Optical Frequency Comb) is an optical spectrum which consists of equidistant lines in frequency space. OFC can thus be used as an optical ruler. Since it was demonstrated in late 1990s, it is revolutionizing many fields in frequency metrology such as the measurement of absolute optical frequencies, the measure ratios of optical frequencies with extremely high precision. It is also used in high-precision spectroscopy. In astronomy, OFC can be used as a very accurate and stable wavelength standard for a high resolution spectrograph to measure the radial velocity of celestial bodies with extremely high accuracy of about several tens cm/s. In our presentation, we will introduce some basic concepts of OFC and some issues to use it in astronomical spectrograph. We will also present our plan to develop a high resolution spectrograph with OFC.

• 한국수소및신에너지학회논문집
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• 제29권5호
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• pp.483-489
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• 2018

Recently proposed organic flash cycle (OFC) was shown to potentially improve power generation using low grade heat source. In this paper, a thermodynamic performance is carried out for a modified OFC employed double expansions. Effects of the selection of working fluid and the important system parameters such as the temperatures in flash evaporators on the system performance were extensively investigated. Results showed that the system performances are strongly influenced with the system parameters and selection of the working fluid, and the power generation can be increased compared to the basic OFC.

• 대한치과교정학회지
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• 제33권3호
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• pp.185-197
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• 2003

비증후군성 구순구개열을 발생시키는 주요유전자로 추측이 되는 OFC1 유전자(위치 염색체 6p24.3)의 한국인에서 나타나는 특성을 연구하였다. 3대에 걸쳐서 처음으로 비증후군성 구순구개열이 나타난 40 명의 환자(남자 20명, 여자 20명, 평균 나이 : 14.2세)와 3대에 걸쳐서 비증후군성 구순구개열을 포함한 어떤 선천성 기형도 나타나지 않았던 정상 성인 40명 (남자 20명, 여자 20명, 평균 나이 : 25.6세)을 연구 대상으로 하였다. 중합효소 연쇄 반응법을 이용하여 OFC1 유전자를 분리 증폭한 후, 염기 서열 분석을 통해서 대립유전자형을 밝히고, BLAST 와 Pedant-Pro 데이터베이스를 이용하여 단백질의 상동성 검색을 수행하였으며, 그 결과는 다음과 같다. 1. OFC1 유전자는 'CA' 연쇄반복서열을 가진 극소위성 표지자로 밝혀졌다. 2. 환자군과 대조군의 OFC1 유전자의 특별한 차이는 발견되지 않았다. 3. 한국인에서 나타난 'CA' 연쇄반복서열의 형태는 'ABI linkage map 2'의 TA(CA)11TA(CA)10과는 달리, TA(CA)n의 형태를 띄었으며, 연쇄반복의 수는 17회에서 26회로 다양하게 나타났다. 4. 'CA' 연쇄반복서열의 횟수에 따라서, 9가지의 대립유전자형이 발견되었으며, 나타나는 빈도는 환자군과 대조군에서 유사하였다. 5. 'ABI linkage map 2'의 'CA' 연쇄반복서열 사이의 염기서열 T가 한국인에서는 C로 치환되어 있었지만, ORF예측을 하였을 때 예상되는 아미노산의 배열 차이는 관찰되지 않았다. 6. 한국인 OFC1 유전자의 염기서열로 예측되는 단백질을 알아보기 위하여 BLAST 검색을 한 결과, Telomerase reverse transcriptase(TERT, locus 5p15.33, NCBI Genome Annotation ; NT023089)와 Nucleotide binding protein 2(NBP2, locus 17q22, NCBI Genome Annotation; NT010783)가 유사한 구조를 가지는 단백질로 밝혀졌다. 7. Pedant-Pro 데이터베이스로 단백질 구조의 상동성 검색을 한 결과, OFC1 유전자는 적어도 하나의 transmembrane region과 non-gloular region을 가지는 구조로 밝혀졌다.

• 생명과학회지
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• 제13권6호
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• pp.865-870
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• 2003

본 연구는 손바닥 선인장 투여 후 급성 $CCl_4$ 로 처리한 흰쥐의 간과 혈청을 사용하여, total cholesterol, HDL-cholesterol, LDL-cholesterol, total lipid, triglyceride (TG)를 간조직중에서 MDA를 측정함으로써 과산화지질 활성도와 콜레스테롤의 양을 조사하였다 OFC군은 손바닥 선인장 200mg/kg을, CTA 군은 saline을 2주간 매일 투여한 다음 간 손상의 유도는 사염화탄소를 olive oil에 1:1 비율로 용해시켜 체중 1kg당 50% $3.3m\ell$ 의용량을 복강으로 해부하기 24시간 전에 반 투여, 12시간 전에 나머지 반 투여하였다. 그 후 10시간 절식 후 혈액과 간을 채취하여 관찰하였다. 간 조직 중의 과산화지질 함량은 CTA 군은 NCT 군에 대하여 31.9% 증가를 보였으나, OFC 군에서는 CTA 군에 대해 32.6% 감소하는 경향을 나타내었다. 혈중 total lipid와 TG의 양은 손바닥 선인장을 투여한 군 (OFC) 이 CTA 군에 비해 각각 16.8%, 52.3%의 유의성 있는 감소를 보였다. Total cholesterol과 LDL-cholesterol은 OFC 군이 CTA 군에 대해 각각 12.7% 17.4% 정도로 크게 감소되는 것으로 나타났다. HDL-cholesterol은 CTA 군이 NCT 군에 대해 42.8% 감소하였으나, 손바닥 선인장을 투여함으로써 CTA 군에 대해 19.7% 증가를 나타냈다. 동맥경화지수는 CTA 군이 NCT 군에 비해 3.6배 높고, OFC 군이 CTA 군에 비해 1.8배 낮은 것으로 나타났다. 이상의 결과로, 손바닥 선인장을 투여한 후 간 독성을 유발하였을 때 과산화지질 및 콜레스테롤이 유의적인 수준으로 억제되었다.

• 광산업정보
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• 통권58호
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• pp.34-37
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• 2010

• 소성∙가공
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• 제29권1호
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• pp.5-10
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• 2020

Heat treatment conditions of 88.5% asymmetrically cold rolled oxygen free copper (OFC) sheets have been studied to obtain an equiaxed fine microstructure with a grain size of less than 10 ㎛. The commercial OFC sheets with the thickness of 10 mm were asymmetrically cold rolled by using equal speed asymmetric rolling (ESAR) processes and total rolling reduction. The thickness of the rolled sheets were 88.5% and 1.15 mm, respectively. An equiaxed fine microstructure of OFC sheets with a grain size of 6.0 ㎛ were obtained when the asymmetrically cold rolled OFC sheets were heat treated at 180℃ for 40 minutes. The tensile strength of the asymmetrically cold rolled specimen increased from 217.6 MPa to 396.1 MPa, while the elongation of the specimen asymmetrically cold rolled and heat treated increased from 29.0% to 66.9% along with an 8% increase of the tensile strength.

• Clinical and Experimental Pediatrics
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• 제57권2호
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• pp.75-78
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• 2014

Purpose: This study aimed to investigate the clinical features of macrocephaly at birth in Korea using ultrasonography. Methods: We retrospectively investigated the medical records of full-term birth neonates in Cheil General Hospital & Women's Healthcare Center from January 2000 to June 2012. The following parameters were recorded and analyzed: gestational age, sex, birth weight, height, occipitofrontal circumference (OFC), physical examination, perinatal problems, and ultrasonography results. Macrocephaly was diagnosed when the OFC was greater than two standard deviations, based on the 2007 Korean National Growth Charts. Results: There were 75 neonates with macrocephaly at birth (52 boys and 23 girls), with a mean OFC of $38.1{\pm}0.49cm$. A comparison of the birth weight and height with the OFC value showed that height was correlated with OFC (r=0.35) but birth weight was not correlated with OFC (r=0.06). There were no remarkable findings in 56 cases (75%). Germinal matrix hemorrhage was identified in 10 cases (13%). An enlarged cerebrospinal fluid space was found in 5 cases (6.7%). There were 3 cases of mega-cisterna magna (4%), 1 case of ventriculomegaly, and 1 case of an enlarged interhemispheric space (6 mm) among these patients. In addition, a choroid plexus cyst was seen in 1 case. Mineralizing vasculopathy in both basal ganglia with no evidence of congenital infection was found in 2 cases and an asymptomatic subarachnoid hemorrhage was found in 1 case. Conclusion: Our results indicate that macrocephaly at birth has benign ultrasonography findings and shows a pattern of male dominance.

• 소성∙가공
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• 제27권4호
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• pp.250-256
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• 2018

Oxygen-free copper (OFC) was prepared as a 90 mm cube and then processed with Multi-Axial Diagonal Forging - Initialization of Prior manufacturing History (MADF). The MADF process has been newly developed as a severe plastic deformation method. The MADF process consists of upset forging with a thickness reduction of 30% and diagonal forging with a diagonal angle of $135^{\circ}$. 1 cycle process consists of a 12 passes forging process. In order to analyze the characteristic changes according to the number of iterations, 1, 2, and 3 cycles of the MADF process were performed. The OFC specimens were MADF processed without surface cracks up to 3 cycles. The microstructure, hardness and tensile test of processed materials were analyzed to study the change of material properties according to the amount of MADF process. The results showed that the MADF process effectively refined the microstructure and increased the strength of OFC. In the case of specimens processed for more than 2 cycles, the grains of all measurement regions were refined to be less than $7{\mu}m$ of grain size. The 1 cycle MADF processed OFC showed the highest mechanical properties with the hardness of 132 HV and tensile strength of 395 MPa. Hardness and strength seemed to be saturated when processed over 2 cycles.

• 대한불안의학회지
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• 제2권2호
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• pp.94-100
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• 2006

Objective : This study was designed to examine the volumetric abnormality of orbitofrontal cortex (OFC) and its change after 2 years of pharmacotherapy in obsessive compulsive disorder (OCD) patients. Method : Volumetric magnetic resonance imaging studies were conducted in 15 OCD patients and 13 normal volunteers. For 2 years, all patients took at least one serotonin reuptake inhibitor and atypical antipsychotics were used as an augmentation therapy in most patients. The follow-up MRI studies were conducted after the pharmacotherapy and OFC volumes were measured by the manual region of interest method. Results : Bilateral OFC volumes of 15 OCD patients were significantly greater than those of the normal volunteers before the treatment. After 2 years of the treatment, significant decrease was observed in bilateral OFC volumes of OCD patients to the extent that left OFC volume of OCD patients was not different from that of the normal volunteers. Conclusion : This finding suggests that OFC is directly related to the pathophysiology of obsessive compulsive disorder.