• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1244-1249
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• 2024

A combination of flow-accelerated corrosion (FAC) tests and corresponding computational fluid dynamics (CFD) tests were performed to determine the hydrodynamic parameters that could help predict the highly susceptible location to FAC in the elbow section. The accelerated FAC tests were performed on a specimen containing elbow sections fabricated using commercial 2-inch carbon steel pipe. The tests were conducted at flow rates of 9 m/s under the following conditions: water temperature of 150 ℃, dissolved oxygen <5 ppb, and pH 7. Thickness reduction of the specimen pipe due to FAC was measured using ultrasonic testing. CFD was conducted on the FAC test specimen, and the turbulence intensity, and shear stress were analyzed. Notably, the location of the maximum hydrodynamic parameters, that is, the wall shear stress and turbulent intensity, is also the same location with maximum FAC rate. Therefore, the shear stress and turbulence intensity can be used as hydrodynamic parameters that help predict the FAC-induced wall-thinning rate. The results provide a method to identify locations susceptible to FAC and can be useful for determining inspection priority in piping systems.

• Journal of Periodontal and Implant Science
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• 제27권2호
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• pp.363-377
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• 1997

The main goal of periodontal therapy is the regeneration of periodontal tissue which has been lost due to destructive periodontal diseases. Although conventional forms of periodontal therapy show sound clinical results, the healing results in long junctional epithelium. There have been numerous materials and surgical techniques developed for new attachment and bone regeneration. Bone grafts can be catagorized into: autografts, allografts, xenografts and bone substitutes. Synthetic bone substitute materials include hydroxyapatite, tricalcium phosphate, calcium carbonate, and Plaster of Paris. Calcium sulfate has found its use in dental practice for the last 30 years. Recent animal studies suggest that periodontal regeneration in 3 wall intrabony defect may be enhanced by the presence of calcium sulfate. And it is well known that 2 wall & 1 wall defect have less osteogenic potential, So we need to study the effect of calcium sulfate in 1 wall intrabony defect in dogs. The present study evaluates the effects of calcium sulfate on the epithelial migration, alveolar bone regeneration and cementum formation in intrabony defects of dogs. Four millimeter-deep one-wall intrabony defects were surgically created in the mesial aspect of anterior teeth and mesial & distal aspects of premolars. The test group received calcium sulfate grafts with a flap procedure. The control underwent flap procedure only. Histologic analysis following 8 weeks of healing revealed the following results: 1. The lengths of junctional epithelium were: 2.52mm in the control, and 1.89mm in the test group. There was no statistical significance between the two groups. 2. Alveolar bone formation were: 0.61mm in the control, and 1.88mm in the test group. There was a statistically significant difference between the two groups (p<0.05). 3. Cementum formations were: l.lmm in the control, and 2.46mm in the test group. There was a statistically significant difference between the two groups (p<0.05). 4. The length of CT adhesion were: O.97mm in the control, and 0.17mm in the test group. There was no statistically significant differences between the two groups These results suggest that the use of calcium sulfate in intrabony defects has little effect on junctional epithelium migration, but has significant effects on new bone and new cementum formations.

• 디자인학연구
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• 제19권2호
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• pp.207-216
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• 2006

벽지는 본래 종이가 지닌 성질상 실내장식에 있어서 수명이 가장 짧다는 특징이 있지만, 벽면의 시각적인 효과의 다양함으로 현대 벽장식 마감재중 가장 중요한 요소가 되었다 벽지는 종이의 특성상 역사적 유물 보존이 어렵고 그에 관한 기록이 미흡하며 건축물의 실내공간이 잘 유지되었거나, 광고로 사용되었던 다양한 상업용 샘플과 여러 책자에 의해서만 고증되고 있다. 종이벽지와 도배 자료들을 근거로 18세기의 영국을 중심으로 현대 벽지도배의 발전과 벽지산업의 이론적 체계 확립을 위해 과거의 전통적 벽지도배의 역사적 배경연구와 기술적, 상업적 배경의 근원을 이론적으로 고찰하여 전통적 벽지도배의 상업적 역사성을 재 인식하고자한다. 벽지도배의 이론적 연구를 통해 전통적 도배방법과 초배지의 전승, 반복이음 방식을 이용한 패턴의 양식화, 벽지도배의 분업화와 상업적 비용의 세분화, 과거 전통접착 방법의 전승, 띠벽지의 유래, 전통적 종이벽지의 실용성과 초기 도배기술의 다양한 기능성, 맞대이음 방식에서 중복이음 방식의 변화, 여성의 벽지선택을 통한 DIY제품의 개발 등을 이론적으로 고찰하였다. 벽지는 지금도 장식적, 기능적 벽 마감재 또는 벽 처리를 위한 가장 대중적인 재료로서 다른 재료들보다도 가장 선호하는 제품으로 남아 있다. 이러한 벽지의 도배 기술과 상업성을 역사적으로 고찰하여 전통 벽지도배의 이론적 체계 확립을 위한 중요한 자료이며 미래 벽지산업의 방법론적 접근을 위한 벽지역사의 근원이 될 수 있는 연구라고 사료된다.

• Journal of Advanced Marine Engineering and Technology
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• 제10권2호
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• pp.156-164
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• 1986

In the case of boiling on high temperature wall, vapor film covers fully or parcially the surface. This phenomenon, film boiling or transition boiling, is very important in the surface heat treatment of metal, design of cryogenic heat exchanger and emergency cooling of nuclear reactor. Mainly supposed hydraulic-thermal accidents in nuclear reactor are LCCA (Loss of Coolant Accident) and PCM (Power-Cooling Mismatch). Recently, world-wide studies on reflooding of high temperature rod bundles after the occurrence of the above accidents focus attention on wall temperature history and required time in transient cooling process, wall superheat at rewet point, heat flux-wall superheat relationship beyond the transition boiling region, and two-phase flow state near the surface. It is considered that the further systematical study in this field will be in need in spite of the previous results in ref. (2), (3), (4). The paper is the study about the fast transient cooling process following the wall temperature excursion under the CHF (Critical Heat Flux) condition in a forced convective subcooled boiling system. The test section is a vertically arranged concentric annulus of 800 mm long and 10 mm hydraulic diameter. The inner tube, SUS 304 of 400 mm long, 8 mm I.D, and 7 mm O.D., is heated uniformly by the low voltage AC power. The wall temperature measurements were performed at the axial distance from the inlet of the heating tube, z=390 mm. 6 chromel- alumel thermocouples of 76 .mu.m were press fitted to the inner surface of the heating tube periphery. To investigate the heat transfer characteristics during the fast transient cooling process, the outer surface (fluid side) temperature and the surface heat flux are computed from the measured inner surface temperature history by means of a numerical method for inverse problems of transient heat conduction. Present cooling (boiling) curve is sufficiently compared with the previous results.

• Archives of Plastic Surgery
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• 제40권6호
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• pp.728-734
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• 2013

Background Absorbable materials offer many advantages in the reconstruction of orbital walls; however, the possibility of postoperative enophthalmos after complete absorption cannot be excluded. We evaluated the postoperative results of absorbable mesh plates used as onlay implanting on the medial orbital wall to determine whether they are suitable for medial orbital wall reconstruction. Methods The study included 20 patients with medial orbital wall fractures who were followed up for more than 2 years postoperatively. We used absorbable mesh plates in all of the patients. We measured the following: the changes in the expanded orbital volume by comparing the preoperative and postoperative computed tomography (CT) scans and the degree of clinical enophthalmos. Results There were no major complications associated with the use of absorbable materials such as infection, migration, or extrusion of mesh plates during the long-term follow-up. The orbital volumetric changes between the preoperative and postoperative CT scans were not statistically significant. However, the expanded orbital volume was not related to the degree of clinical enophthalmos. Conclusions The reconstructed orbital wall may provide supportive scar tissue to the orbital contents even after the absorbable materials have dissolved completely. Absorbable mesh plates could be another option for the reconstruction of the medial orbital wall.

• 한국방재학회 논문집
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• 제7권1호통권24호
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• pp.1-9
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• 2007

본 연구는 국내에 시공된 조적조 건축물의 특징을 반영한 조적벽체의 반복가력과 모의진동대 실험을 통해 얻어진 결과를 근거로 하여 유리섬유로 보강된 보강조적벽체의 전단내력식을 제안하는 것을 목적으로 한다. 실험결과, 개구부가 없는 조적벽체의 파괴를 지배하는 모드는 Rocking이였고, 개구부가 있는 경우는 개구부 주변에 균열이 집중되었다. 비보강 조적벽체의 전단내력식은 UBC에서 제시한 식이 실험과 가장 유사한 값을 보였다. 본 연구를 통해 제안되어지는 유리섬유 보강조적벽체의 전단내력식은 다음과 같다. $$V_n=0.02A_n{\sqrt{f'_m}}+0.022b_gh_g(1+2{\alpha})^3{\sqrt{f_g}}(N/mm^2)$$.

• Korean Journal of Radiology
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• 제22권1호
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• pp.63-71
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• 2021

Objective: To identify the CT findings associated with treatment failure after antibiotic therapy for acute appendicitis. Materials and Methods: Altogether, 198 patients who received antibiotic therapy for appendicitis were identified by searching the hospital's surgery database. Selection criteria for antibiotic therapy were uncomplicated appendicitis with an appendiceal diameter equal to or less than 11 mm. The 86 patients included in the study were divided into a treatment success group and a treatment failure group. Treatment failure was defined as a resistance to antibiotic therapy or recurrent appendicitis during a 1-year follow-up period. Two radiologists independently evaluated the following CT findings: appendix-location, involved extent, maximal diameter, thickness, wall enhancement, focal wall defect, periappendiceal fat infiltration, and so on. For the quantitative analysis, two readers independently measured the CT values at the least attenuated wall of the appendix by drawing a round region of interest on the enhanced CT (HU_post) and non-enhanced CT (HU_pre). The degree of appendiceal wall enhancement (HU_sub) was calculated as the subtracted value between HU_post and HU_pre. A logistic regression analysis was used to identify the CT findings associated with treatment failure. Results: Sixty-four of 86 (74.4%) patients were successfully treated with antibiotic therapy, with treatment failure occurring in the remaining 22 (25.5%). The treatment failure group showed a higher frequency of hypoenhancement of the appendiceal wall than the success group (31.8% vs. 7.8%; p = 0.005). Upon quantitative analysis, both HU_post (46.7 ± 21.3 HU vs. 58.9 ± 22.0 HU; p = 0.027) and HU_sub (26.9 ± 17.3 HU vs. 35.4 ± 16.6 HU; p = 0.042) values were significantly lower in the treatment failure group than in the success group. Conclusion: Hypoenhancement of the appendiceal wall was significantly associated with treatment failure after antibiotic therapy for acute appendicitis.

• Journal of Chest Surgery
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• 제21권2호
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• pp.379-382
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• 1988

We have experienced a case of right side chylothorax following closed chest injury. A 35-year-old man in his car was accidentally collided against obstacles on September 19, 1986 resulting in a contusion on right anterior chest wall. The only complaint noted on admission was right chest pain. Chest X-ray showed near total radiopaque density of right thorax. Conservative treatment of closed tube thoracostomy at right pleural cavity through midaxillary 7th intercostal space had been continued for 25 days without improvement. Chyle outflow through the chest tube was averaging 1,700cc per day. Oversewing of the thoracic duct and pleura by silk and pledgetted prolene sutures were done. There was no complication and recurrence till postoperative 20 days. Chylothorax following closed chest injury was never reported in this country, and will be a interesting clinical case report.

• Archives of Plastic Surgery
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• 제42권4호
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• pp.424-430
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• 2015

Background Reconstruction of combined orbital floor and medial wall fractures with a comminuted inferomedial strut (IMS) is challenging and requires careful practice. We present our surgical strategy and postoperative outcomes. Methods We divided 74 patients who underwent the reconstruction of the orbital floor and medial wall concomitantly into a comminuted IMS group (41 patients) and non-comminuted IMS group (33 patients). In the comminuted IMS group, we first reconstructed the floor stably and then the medial wall by using separate implant pieces. In the non-comminuted IMS group, we reconstructed the floor and the medial wall with a single large implant. Results In the follow-up of 6 to 65 months, most patients with diplopia improved in the first-week except one, who eventually improved at 1 year. All patients with an EOM limitation improved during the first month of follow-up. Enophthalmos (displacement, 2 mm) was observed in two patients. The orbit volume measured on the CT scans was statistically significantly restored in both groups. No complications related to the surgery were observed. Conclusions We recommend the reconstruction of orbit walls in the comminuted IMS group by using the following surgical strategy: usage of multiple pieces of rigid implants instead of one large implant, sequential repair first of the floor and then of the medial wall, and a focus on the reconstruction of key areas. Our strategy of step-by-step reconstruction has the benefits of easy repair, less surgical trauma, and minimal stress to the surgeon.

• 한국조경학회지
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• 제30권1호
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• pp.44-51
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• 2002

The objective of this project is to improve the environment of the estuary dike on the Youngsan-River through Re-landscaping. An estuary dike of the Youngsan-River, the largest in the Orient, was constructed in 1981 and connects Mokpo City and Youngam-Gun province. Twenty years ago, when this dike was completed, this place was one of the famous tourist attractions of Korea. It symbolized the development and growth of Korea. But this dike at present is only a dreary sight as a huge concrete construction element. Therefore, a wall painting on the estuary dike was planned to improve this image. The site, an estuary dike of the Youngsan-River, is located in Mokpo City and its length is about 1,360m. The planning focus of this re-landscaping, which is a proposed improvement design through the analysis of characteristics and problems in conventional facilities, is as follows: (1) Introduction of a wall painting that is a symbol of the sea and river (by the creation of an illusion), (2) Production of the wall painting which is under consideration to create a friendly atmosphere of the circumference view and (3) Preparation of a design to establish an approach to the waterfront. By following these steps, an estuary dike can function as a tourist attractions and can be transformed in to cultural space for civilian. This project is good example of environment design that is completed with the regional residents participation through community input in the planning and initiation of a wall painting. The concept of environment design which involves the residents participation and re-landscaping in Korea has not been established up to now on. However, as this projects has proven, consideration for regional residents is a very important factor for the administrative office and planing specialist to address. In the future, it will have a direct influence on the development of design planning. If the establishment of space that can be accepted by residents with love, affection and self-confidence is possible, environment design in which residents participate actively, can be realized.