• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2150-2156
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• 2018

We suggest a systematic method for obtaining the optimal compression ratio in the multi-stage closed-loop compression process of carbon dioxide. Instead of adopting the compression ratio of 3 to 4 by convention, we propose a novel approach based on mathematical analysis and simulation. The mathematical analysis prescribes that the geometric mean is a better initial value than the existing empirical value in identifying the optimal compression ratio. In addition, the optimization problem considers the initial installation cost as well as the energy required for the operation. We find that it is best to use the fifth stage in the general closed-loop type carbon dioxide multi-stage compression process.

• 한국주거학회논문집
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• 제24권2호
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• pp.69-76
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• 2013

With people leaving the countryside to the cities as a result of industrialization and urbanization and drastic reduction of school children due to low birthrate, nationwide, total 3,438 schools have been shut down following the closed schools policy. Consequently, local governments have been active in selling, utilizing, and leasing the closed schools but there are still 466 closed schools that need to be addressed quickly. In addition to this phenomenon, aging population has become an important issue, and demand for elderly welfare facilities population is also increasing as a result. However, the supply of welfare services remains inadequate. This study was conducted in an attempt to solve both local and social problems at the same time, caused by the closing of schools and an aging population, through the use of closed schools as elderly welfare facilities, and suggests plans for per-unit space according to its type, and prototype, through research analysis of practical use, based on case studies. With the conclusions of both advantages and disadvantages, drawn from its type, we are hoping to be able to use this study by adapting its type, or mixing, according to one's needs.

• 교육녹색환경연구
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• 제18권2호
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• pp.1-11
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• 2019

본 연구는 지속적으로 증가가 예상되는 폐교시설의 효율적인 활용을 위하여 활용지표의 개발을 통해 폐교 활용 시 객관적인 의사결정을 위한 목적을 가진다. 연구 단계는 크게 폐교 활용 예비지표 도출, 빅데이터를 활용한 최종지표 도출, 지표의 정량화 단계로 구분하여 진행하였으며, 최종적으로 지표를 정량화함으로써 객관화하였다. 향후 지표를 기준으로 시설에 적용 및 검증하고자 한다. 본 연구는 지금까지 폐교시설의 활용을 위한 계획 및 연구에 있어서 시도되지 않았던 빅데이터 분석기법을 적용한 것에 그 의의가 있다.

• 한국농촌건축학회논문집
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• 제22권2호
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• pp.18-25
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• 2020

Recently (2019), more than 3,800 schools have been closed in Korea due to the decrease in the number of students. Among them, 1,000 closed schools were used, 400 unused closed schools were sold, and the remaining 2,400 were sold. However, considering the absolute lack of elderly facilities due to the aging population, it seems necessary to recycle these public assets into elderly facilities. The purpose of this study is to explore the cases of remodeling closed schools in Japan and recycling them as elderly facilities, and to find ways to resolve the very serious shortage of elderly facilities while seeking measures to closed schools in Korea. The results of this study are summarized as follows: 1) In the case of Shinagawa in Tokyo, it was easy to change its use because the building was owned by the old district. 2) The existing classroom space was used as it was to create an elderly living space consisting of two or three rooms and one bathroom unit. 3) In case 2, even if the earthquake-resistant structure was reinforced, the overall construction cost was reduced by 30% compared to the new construction.

• 대한두개안면성형외과학회지
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• 제23권3호
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• pp.119-124
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• 2022

Background: Many severe nasal bone fractures present with septal fractures, causing postoperative septal deviation and negatively affecting the patients' quality of life. However, when a septal fracture is absent, it is difficult to predict whether surgical correction can help minimize nasal septal deviation postoperatively. This study determined whether performing closed reduction on even mildly displaced nasal bone fracture could deter the outcome of septal deviation. Methods: We retrospectively reviewed the data of 116 patients aged 21-72 years who presented at the outpatient clinic and emergency room with fractures of nasal bones only without any involvement of the septum from January 2014 to December 2020. Patients were classified into three fracture type groups: A (unilateral), B (bilateral), and C (comminuted with depression). The degree of septal deviation was calculated by measuring the angle between the apex of the most prominent point and the crista galli in the coronal view on computed tomography images. The difference between the angles of the initial septal deviation and that of the follow-up was calculated and expressed as delta (Δ). Results: Closed reduction tended to decrease the postoperative septal deviation in all fracture types, but the values were significantly meaningful only in type A and B fractures. In the surgical group, with type A as the baseline, type B showed a significantly larger Δ value, but type C was not significantly different, although type C showed a smaller Δ value. In the conservative group, with type A as the baseline, the other fracture types presented significantly lower Δ values. Conclusion: For all fracture types, closed reduction significantly decreased the extent to which the nasal septum likely deviated. Therefore, when a patient is reluctant to undergo closed reduction, physicians should address the possible outcomes and prognosis of untreated nasal bone fractures.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제27권4호
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• pp.372-380
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• 2005

Condylar process of mandible, has the specialized anatomic structure compared with any other body structure, acts directly in connection with mastication and speech and so on. In general, mandibular condyle fractures have been managed by two methods as open and closed reduction. But, there are no reasonable consensus about the proper management of this injury. This study was designed for analysis of the prognosis of two methods of treatment, open and closed reduction, with positional change of fractured condyle and complications within 6 months post-intermaxillary fixation period. We conducted a retrospective analysis of 154 patients whose unilateral mandibular condyle fractures were treated by open or closed reduction in our department. The horizontal, sagittal, and coronal change of the condyle was examined using modified Towne's and panoramic radiographs before intermaxillary fixation(IMF), immediately after IMF, and at 6 months after IMF. Patients, whose mandibular condyle fractures were treated by closed reduction, had significantly shorter ramus height on the side of injury(P<0.05). But, fractured condylar fragments were displaced insignificantly with aspect to sagittal and coronal plane(P>0.05). The level of the fracture influenced the ramus length and the degree of coronal change in the closed reduction group(P<0.05). There was no significant correlation among the level of the fracture, treatment methods and complications(P>0.05). From the results obtained in this study, fractured mandibular condyles, were treated by closed reduction, had a tendency that continuous condylar displacement was occurred with aspect to horozontal and coronal plane in treatment period including intermaxillary fixation. And then there was a correlation between the level of the fracture and the position change in close reduction group statistically. These result suggested that care must be taken in basing treatment decisions on the degree of displacement of the condyle and in treating the mandibular condyle fractures for a long time.

• 한국농촌건축학회논문집
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• 제20권1호
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• pp.53-60
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• 2018

The purpose of this study is to present the basic data for the active use of closed schools by analyzing the actual conditions of closed schools in Gyeongnam area. As a method of this study, we examined the population change in Gyeongnam area through the literature survey and the internet site survey, and grasped the characteristics of the policies related to the closed school. Through the homepage survey of the local education financial alerts, we analyzed the contents, location, period after the closure, land area, and total floor area of the closed schools that have been in use or invaluable as of March 2017. As the results, In the case of self-utilization, the utilization rate of educational facilities was overwhelmingly high. In the case of lease utilization, the utilization ratio was higher in the order of education facilities, income increase facilities, and cultural facilities. Overall, 62.8% of the closed schools are located in the base towns (urban areas). The average of the period after the closure was 16.2 years, the land area average was $9,291.1m^2$, and the total area average was $1,153.8m^2$.

• 교육시설 논문지
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• 제25권5호
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• pp.13-20
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• 2018

The purpose of this study is to provide a fundamental data and establish policies for the utilization of closed schools in Korea. The closed schools have been increased in Korea because not only the birth rate, and the number of students have been decreased, but also a greate number of people have moved to big cities or the elderly population is increasing. In this context, this research explores the current circumstance of Japan where experienced the similar phenomenon before Korea had. The results of this study are summarized as follows: The reason for the closed schools in Japan is a decrease in population due to the urbanization and reducing students themselves by aging. The recycling proportion of the closed schools is only approximately 62% in Japan. It means that fewer facilities have been recycled due to the transfer of the managemental departments and the lack of budgets for purchasing the closed schools. As the number of children decreases, but elderly people increases as the same time, it is necessary to positively examine the transition of the closed schools to new facilities for the elderly people. Even though the number of children had been declined, and it is recently turning back to an increasing of the residential children in 23 districts of Tokyo, there are still existing many closed schools. This phenomenon is caused by the decrease of the children and residential areas due to the aging and urbanization. For these reasons, there are many diverse demands for the practical and valuable recycling of the closed schools. However, it seems that there are few cases of successful disposal or transfer of management to other suitable ministry. Therefore, it is necessary for the closed schools to be remodeled the facilities required by current residents.

• 호남수학학술지
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• 제30권2호
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• pp.335-341
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• 2008

In this paper, we use the convexity of distance function between geodesics in a singular Hadamard space to generalize Hadamard-Cartan theorem for 2-dimensional metric spaces. We also determine a neighborhood of a closed geodesic where no other closed geodesic exists in a complete space of nonpositive curvature.

• 한국해양공학회지
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• 제18권2호
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• pp.46-51
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• 2004

Natural frequencies of the transverse vibration of beams with step change in cross-section are obtained by using the asymptotic closed form solution. This closed form solution is found by using WKB method under the assumption of slowly varying properties, such as mass, cross-section, tension etc., along the beam length. However, this solution is found to be still very accurate even in the case of large variation in cross-section and tension. Therefore, this result can be easily applied to many engineering problems.