• The Journal of Advanced Prosthodontics
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• 제6권4호
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• pp.253-258
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• 2014

PURPOSE. To compare marginal and internal gaps of zirconia substructure of single crowns with those of three-unit fixed dental prostheses. MATERIALS AND METHODS. Standardized Co-Cr alloy simulated second premolar and second molar abutments were fabricated and subsequently duplicated into type-III dental stone for working casts. After that, all zirconia substructures were made using $Lava^{TM}$ system. Marginal and internal gaps were measured in 2 planes (mesial-distal plane and buccal-palatal plane) at 5 locations: marginal opening (MO), chamfer area (CA), axial wall (AW), cusp tip (CT) and mid-occlusal (OA) using Replica technique. RESULTS. There were significant differences between gaps at all locations. The $mean{\pm}SD$ of marginal gap in premolar was $43.6{\pm}0.4{\mu}m$ and $46.5{\pm}0.5{\mu}m$ for single crown and 3-unit bridge substructure respectively. For molar substructure the $mean{\pm}SD$ of marginal gap was $48.5{\pm}0.4{\mu}m$ and $52.6{\pm}0.4{\mu}m$ for single crown and 3-unit bridge respectively. The largest gaps were found at the occlusal area, which was $150.5{\pm}0.5{\mu}m$ and $154.5{\pm}0.4{\mu}m$ for single and 3-unit bridge premolar substructures respectively and $146.5{\pm}0.4{\mu}m$ and $211.5{\pm}0.4{\mu}m$ for single and 3-unit bridge molar substructure respectively. CONCLUSION. Independent-samples t-test showed significant differences of gap in zirconia substructure between single crowns and three-unit bridge (P<.001). Therefore, the span length has the effect on the fit of zirconia substructure that is fabricated using CAD/CAM technique especially at the occlusal area.

• 대한기계학회논문집B
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• 제30권6호
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• pp.505-513
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• 2006

The pressure drop characteristics in a rotating two-pass duct with rib turbulators are investigated in the present study. Three ducts of different aspect ratios (W/H=0.5, 1.0 and 2.0) are employed with a fixed hydraulic diameter ($D_h$) of 26.7 mm. $90^{\circ}$-rib turbulators with $1.5mm{\times}1.5mm$ cross-section are attached on the leading and trailing surfaces. The pitch-to-rib height ratio (p/e) is 1.0. The distance between the tip of the divider and the outer wall of the duct is 1.0 W. The thickness of divider wall is 6.0 mm o. 0.225 $D_h$. The Reynolds number (Re) based on the hydraulic diameter is kept constant at 10,000 and the .elation number (Ro) is varied from 0.0 to 0.2. As duct aspect ratio increases, high friction factor ratios show in overall regions. The reason is that the rib height-to-duct height ratio (e/H) increases, but the divider wall thickness-to-duct width ($t_d/W$) decreases. The rotation of duct produces pressure drop discrepancy between the leading and trailing surfaces. However, the pressure drop discrepancy of the high duct aspect ratio (AR=2.0) is smaller than that of the low duct aspect ratio (AR=0.5) due to the decrement of duct hight (H).

• 공업화학
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• 제18권1호
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• pp.94-97
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• 2007

대기압 조건에서 고정층 상압 유통식 반응기를 사용하여 Pd(5)/SPK 촉매상에서 산소의 몰 비 변화에 따른 메탄의 열분해 반응으로부터 탄소 나노튜브 및 탄소 나노선을 제조하였으며, SEM과 TEM을 이용하여 분석하였다. $CH_4/O_2$의 몰 비가 1인 경우, 촉매층 지지대 표면상에 탄소가 거의 침적되지 않았으나, $CH_4/O_2$의 몰 비가 2인 경우에는 촉매층 지지대 표면상에 반응기를 봉쇄할 정도로 다량의 탄소가 침적되었다. 침적된 탄소를 SEM과 TEM을 통하여 분석한 결과 많은 수의 단일 벽 탄소 나노튜브와 탄소 나노선들이 만들어졌음을 확인할 수 있었다. 촉매 표면상에 침적된 탄소 나노튜브의 생성 메카니즘은 첨단성장방식이었고, 촉매 지지대 표면상에 만들어진 탄소 나노튜브 및 나노선들의 생성은 일정한 탄소 성장속도 벡터와 탄소 나노선의 링구조의 핵형성이 중요한 역할을 하였다. SPK 촉매 담체는 열 안정성이 우수하였으며, $N_2$ 흡착등온선은 중기공 세공이 잘 발달된 IV형이었다.

• Journal of Periodontal and Implant Science
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• 제23권3호
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• pp.605-621
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• 1993

The gingival hyperplasia refers to an increase in the size of the gingival tissue produced by an increase in the number of its component cells. In order to investigate the cellular change in epithelium and subepithelial tissue of noninflammatory gingival hyperplasia, the gingival tissues were surgically obtained from the patients with dilantin gingival hyperplasia and idiopathic gingival hyperplasia. The excised tissue samples were fixed in neutral formalin for 6-24 hours, embedded with paraffin, sectioned at $4-6{\mu}m$ in thickness, mounted on glass slides coated with 3-aminopropyltriethoxysilane(Sigma Chemical Co., St. Louis, MO, U.S.A.) and immunocytochemically processed by Avidin-Biotin peroxidase complex method for detecting proliferating cell nuclear antigen, tenascin and collagen type IV. Monoclonal mouse anti-human PCNA antibody(Oncogene Science, Uniondale, NY, U.S.A., 1 : 250,000), monoclonal mouse anti-human tenascin antibody(Chemicon-International Inc., Temecula, CA, U.S.A., 1:5,000), and monoclonal mouse anti-human collagen type IV(Dakopatts, Glostrup, Denmark, 1: 50) were used as primary antibodies. The results were as follows: 1. In non-inflammatory gingival hyperplasia, the positive reaction to proliferating cell nuclear antigen was localized in the basal cell layer of gingival epithelium and well-developed rete pegs. 2. The positive reaction to tenascin was shown in the connective tissue subjacent to basament membrane of gingival tissue, and especially strong positive reaction was noted in the tip portion of connective tissue projections. 3. The positive reaction to collagen type IV was localized along the basement membranes of gingival epithelium and blood vessels. The results suggest that connective tissue enlargement may affect the proliferation of gingival epithelium.

• 대한치과의사협회지
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• 제57권11호
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• pp.672-678
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• 2019

AIM: The purpose of this study was to evaluate and compare the torsional fracture resistances, cyclic fatigue resistance, and bending stiffness of two nickel-titanium (NiTi) rotary instruments made of different heat-treated alloy: Aurum Blue (heat-treated) and Aurum Pro (conventional). Methods: Forty-five Aurum Blue and Aurum Pro NiTi files were selected for the three mechanical tests (n=15). For the torsional resistance test, 3 mm file tip was fixed and the shaft was driven clockwise at 2 rpm until fracture occurred by using a customized device. Cyclic fatigue resistance was evaluated by rotating instruments in artificial canal with dynamic mode. Bending stiffness was tested by observation of the bending moment on attaining a 45° bend. The results were analyzed by student-t tests at a significance level of 95%. The fractured surface of each groups were examined under a scanning electron microscope (SEM). Results: Aurum Blue showed significantly higher toughness, ultimate strength, distortion angle, and number of cycles to failure than those of Aurum Pro (p < 0.05). However, Aurum Blue and Aurum Pro did not differ significantly in terms of bending stiffness. SEM showed typical topographic appearances of the cyclic fatigue and torsional fracture. Conclusions: Under the limitations of this study, heat-treated instruments showed higher flexibility and fracture resistances than conventional NiTi instruments.

• 한국수정란이식학회지
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• 제11권2호
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• pp.103-109
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• 1996

The aim of this study was to evaluate the effect of recombinant bovine somatotropin (bST; Boostin-S, LG Chem) treatment with FSH (Super OV) or PMSG on superovulatory response for transvaginal ultrasound-guided oocyte retrieval (TVR) in calves. Eight Korean Native Cattle(KNC) heifer calves; 150 to 240 days old; were randomly assigned to four treatment groups: 1) FSH(75 mg); 2) FSH (75 mg) + bST(500mg) 3) PMSG(1;000 IU); 4) PMSG(1, 000 IU) + bST(500 mg). Experimental calves in group 1 (n=2) and 2(n=2) were weekly superovulated for 4 consecutive weeks with daily injection of FSH for 3days and the next day subjected to TVR session. Animals in group 3 (n=2) and 4(n=2) were weekly stimulated for 4 consecutive weeks with a single dose of 1, 000 IU PMSG. TVR was performed on 72 hours after PMSG injection. Calves in group 2 and 4 was received injection of 500 mg of bST every 10 days. At each TVR session, follicle number and size were recorded; the oocytes collected and graded according to cumulus and cytoplasm investment. Collected oocyte were determined viable oocyte according to morphological quality with granulation of oocyte and number and status of cumlulus cells. IVM and IVF were performed and assessed cleavage rate on day 3 after fertilization. A Sonovet 600(Medison, Co., Ltd) realtime ultrasound scanner with a 6.5 MHz convex transducer, fixed at the tip of 500 mm estended handle equipped with a needle guide was used in collecting oocyte. Differences between groups were analysed by chi-square test. The population of large follicle ($\geq$5 nun) and aspiration rate were not significant different among the 4 groups. But, the number of small follicles (<5 mm) and aspirated oocyte in the KNC calves treated with bST were 1.3~1.6 times higher than in KNC calves treat with FSH or PMSG alone. In conclusion, the administration of bST with FSH or PMSG at superovulation for TVR in calves was increase the nurnber of small follicle which was influenced the number of aspiratable follicle.

• 대한토목학회논문집
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• 제29권4A호
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• pp.299-305
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• 2009

본 연구에서는 철도교의 세로보 절취부에서의 피로균열 발생 원인을 연구하기 위하여 실제로 피로균열이 발생한 철도교를 연구대상으로 실물크기의 가로보-세로보 바닥틀 모형을 제작하고 실내실험을 수행하였다. 연구 결과 세로보 상부절취부에서의 피로균열 발생원인은 세로보의 단부에서 발생하는 부모멘트에 의한 상부절취부 복부판의 면내응력의 반복적 작용 결과이고, 하부절취부에서의 피로균열 발생 원인은 세로보 단부의 고정단에 대한 하부절취부 복부판의 상대적 면외변형에 의해 발생하는 면외응력의 반복적 작용 결과라는 결론을 얻었다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.221-221
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• 2022

Chromosome breakage occurred by DNA methylation inhibitor. Zebularine is known as DNA methylation inhibitor and suitable for water solubility among different DNA methylation inhibitors as 5-Azacytidine and 5-aza-2'-deoxycytidine. We used zebularine as mutagen according to different methods by roots absorption and seed imbibition. After zebularine treatment, DNA methylation inhibitor, we observed mitotic chromosome behavior what is different according to two different treatment methods. First, seed imbibition treatment in 1,000 μM of zebularine solution for 72 hours in dark conditions. The second treatment to seedlings of Keumkang was also treated in 1,000 μM of zebularine solution for 72 hours after germination. Root and shoot showed different elongations in each treatment. Root absorption treatment(3.01±0.48, 2.00±0.26) showed the shortest elongation in root and shoot than control(8.16±0.61, 4.03±0.48) and seed imbibition treatment(4.33±0.80, 2.48±0.36). It can be explained root tip meristematic cell activity was damaged by DNA methylation inhibitor. Primary root tips were collected in DW for 24 hours at low temperature(0℃) and fixed in fixation solution for 3 days to chromosome observation in mitosis. Mitotic index, chromosome structure and chromosome aberration were observed by phase-contrast microscope. Mitotic index of the control(0.29) showed twice mitotic cells as the treated groups(imbibition 0.15, absorption 0.14). Observation of chromosomes showed some short chromosomes and loosen chromosomes affected by zebularine. It is considered because of zebularine damage DNA in mitosis. We observed "gap by chromosome breakage" in chromosomes that have loose parts between centromere and telomere. It seems demethylation of zebularine occurs chromosome breakage.

• Journal of Korean Neurosurgical Society
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• 제30권9호
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• pp.1094-1102
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• 2001

Objective : During the trans-condylar or trans-jugular approach for the lesion of cranio-cervical junction(CCJ), its necessary to identify the accurate locations of vertebral artery(VA), internal jugular vein(IJV) and its related lower cranial nerves. These neurovascular structures can also be damaged during the operation for vascular tumor or traumatic aneurysm around extra-jugular foramen, because of their changed locations. To reduce the neurovascular injury at the operation for CCJ, morphometric relationship of its surrounding neurovascular structures based on the tip of the transverse process of atlas(C1 TP), were studied. Materials & Methods : Using 10 adult formalin fixed cadavers, tip of mastoid process(MT) and TPs of atlas and axis were exposed bilaterally after removal of occipital and posterior neck muscles. Using standard caliper, the distances were measured from the C1 TP to the following structures : 1) exit point of VA from C1 transverse foramen, 2) branching point of muscular artery from VA, 3) entry point of VA into posterior atlanto-occipital membrane(AOM), 4) branching point of C-1 nerve. In addition, the distances were measured from the mid-portion of the posterior arch of atlas to the entry point of the VA into AOM and to the exit point of the VA from C1 transverse foramen. After removal of the ventrolateral neck muscles, neurovascular structures were exposed in the extra-jugular foraminal region. Distances were then measured from the C1 TP to the following structures : 1) just extra-jugular foraminal IJV and lower cranial nerves, 2) MT and branching point of facial nerve in parotid gland. In addition, distance between MT and branching point of facial nerve was measured. Results : The VA was located at the mean distance of 12mm(range, 10.5-14mm) from the C1 transverse foramen and entered into the AOM at the mean distance of 24mm(range, 22.8-24.4mm) from the C1 TP. The mean distance from the mid portion of the C1 posterior arch was 20.6mm(range, 19.1-22.3mm) to the entry point of the VA into AOM and 38.4mm(range, 34-42.4mm) to the exit point of the VA from C1 transverse foramen. Muscular artery branched away from the posterior aspect of the transverse portion of VA below the occipital condyle at the mean distance of 22.3mm(range, 15.3-27.5mm) from the C1 TP. The C-1 nerve was identified in all specimens and ran downward through the ventroinferior surface of the transverse segment of VA and branched at the mean distance of 20mm(range, 17.7-20.3mm) from the C1 TP. The IJV was located at the mean distance of 6.7mm(range, 1-13.4mm) ventromedially from the lateral surface of the C1 TP. The XI cranial nerve ran downward on the lateral surface of the IJV at the mean distance of 5mm(range, 3-7.5mm) from the C1 TP. Both IX and X cranial nerves were located in the soft tissue between the medial aspect of the internal carotid artery(ICA) and the medial aspect of the IJV at the mean distance of 15.3mm(range, 13-24mm) and 13.7mm(range, 11-15.4mm) from the C1 TP, respectively. The IX cranial nerve ran downward ventroinferiorly crossing the lateral aspect of the ICA. The X cranial nerve ran downward posteroinferior to the IX cranial nerve and descended posterior to the ICA. The XII cranial nerve was located between the posteroinferior aspect of the IX cranial nerve and the posterior aspect of the ICA at the mean distance of 13.3mm(range, 9-15mm) ventromedially from the C1 TP. The distance between MT and C1 TP was 17.4mm(range, 12.5-23.9mm). The VII cranial nerve branched at the mean distance of 10.2mm(range, 6.8-15.3mm) ventromedially from the MT and at the mean distance of 17.3mm(range, 13-21mm) anterosuperiorly from the C1 TP. Conclusion : This study facilitates an understanding of the microsurgical anatomy of CCJ and may help to reduce the neurovascular injury at the surgery around CCJ.

• Radiation Oncology Journal
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• 제13권4호
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• pp.403-409
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• 1995

목적 : 정위적방사선수술시 방사선조사가 이루어지기 전에 두개내의 정위적 표적을 실제 치료위치에서 직접 확인해서 방사선수술의 안정성과 정확성을 높이고자 함. 방법 : 실제 환자의 치료전에 두부의 인체모형의 조각들 사이에 선량측정용 필름을 넣고 가는 침의 끝으로 찌른 부분을 가상적인 표적으로 삼아 컴퓨터단층촬영용 localizer 를 달고 컴퓨터단층촬영을 한 후 방사선수술용컴퓨터로 영상획득을 해서 가상적 표적점의 정위적좌표를 구한다. 이어서 두부의 인체모형을 선형가속기의 table 에 고정시키고 앞에서 구한 표적점의 좌표에 선형가속기의 laser isocenter 를 일치시킨 후 혈관촬영용 localizer 를 달고 전후와 좌우방향의 사진을 찍는다. 이렇게 찍은 port 필름의 분석으로 얻은 정위적좌표와 컴퓨터단층 촬영의 영상획득 (image acquisition) 으로 이미 구한 정위적좌표를 비교해서 차이를 교정해 준 뒤 3 개의 arc 로 정위적 방사선수술을 시행하고 두부의 인체모형에 삽입되었던 필름을 현상하여 선량분포의 중심과 가는 침으로 만든 구멍으로 표시된 표적점의 거리를 필름농도계를 이용하여 측정한다. 실제 환자치료시에도 컴퓨터단층촬영용 localizer 와 혈관촬영용 localizer 를 써서 정위적좌표를 구하는 과정은 인체모형을 이용한 연구에서와 같다. 두 좌표의 차이를 교정한 후 실제 치료로 진행한다. 결과 : 인체모형연구에서는 선량분포의 중심과 표적점의 차이가 0.3 mm 로 잘 일치했다. 실제 환자 1 예 에서는 컴퓨터단층촬영의 영상으로 부터 구한 isocenter 의 좌표와 실제 치료위치에서 혈관촬영용 localizer 를 이용하여 구한 isocenter 의 좌표가 0.6 mm 의 차이를 보여 잘 일치하였다. 결론 : 방사선수술시 정위적 표적점을 방사선조사전에 치료위치에서 확인하므로써 방사선 수술과정의 정확성과 안전성을 높일 수 있었다.