• 천문학회보
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• 제37권1호
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• pp.39.2-39.2
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• 2012

We present our study on a comparison of dark matter halo merger history from the runs using different numerical simulation codes. To analyze the uncertainty caused by the use of different N-body calculation methods, we compare the results from two cosmological hydrodynamic simulation codes GADGET-2 and RAMSES, which use a TreePM algorithm and the Adaptive Mesh Refinement(AMR) technique respectively. We perform cosmological dark matter-only simulations with the same parameter set and initial condition for both. The dark matter halo mass functions from two simulation runs correspond well with each other, except for lower mass haloes. The discrepancy on the low-mass haloes in turn causes a notable difference in halo merger rate, especially for the case of extremely minor merger. The result from GADGET-2 predicts that most haloes undergo more number of mergers with small haloes than that from RAMSES, independent of halo mass and environment. However, in the context of the study on galaxy evolution, such extreme minor mergers generally do not have strong effects on galaxy properties such as morphology or star formation history. Hence, we suggest that this uncertainty could be quantitatively negligible, and the results from two simulations are reliable even with only minor difference in merger history.

• 한국기계가공학회지
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• 제11권4호
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• pp.72-81
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• 2012

This study investigates structural, fatigue and modal analyses at bicycle suspension seat post. When weight is applied to the saddle, models 1 and 2 have the weakest strength at the part connected with saddle. And model 2 is greater total deformation and equivalent stress than model 1. Among the cases of nonuniform fatigue loads at models 1 and 2, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-10^4MPa$ and the amplitude stress of 0 to $10^4MPa$, the possibility of maximum damage becomes 4%. This stress state can be shown with 5 to 7times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. Model 1 has better impulse relaxation and passenger sensitivity than model 2. The structural result of this study can be effectively utilized with the design of bicycle suspension seat post by investigating prevention and durability against its damage.

• 한국생산제조학회지
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• 제21권3호
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• pp.451-458
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• 2012

This study aims at the structural analysis with fatigue according to the configuration of railway vehicle wheel. Maximum equivalent stress or deformation is shown at the lower face in contact with wheel and rail. As model B has the maximum stress or deformation which becomes lower than model A, model B is shown to have more durability than model A. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample history' with the average stress of 0 to $-10^{11}$ Pa and the amplitude stress of 0 to $10^{10}$ Pa, the possibility of maximum damage becomes 3%. This stress state can be shown with 6 times more than the damage possibility of 'SAE Bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the design of railway vehicle wheel by prevention and durability against its damage.

• 한국수학사학회지
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• 제19권4호
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• pp.117-132
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• 2006

본 논문의 연구자는 중등과정 <7-나 단계> 작도 단원의 의미 있는 학습을 위하여, 자연스러운 발생을 강조하는 Clairaut의 <기하학 원론>을 기반으로 한 5차시 학습 자료를 개발하였다. 중학교 1학년 학생 6명을 대상으로 이를 적용한 수업을 실시하였고, 작도문제 해결을 분석에서 시작하여 작도, 확인 및 탐구로 이어지는 학습 과정의 특징을 분석하였다.

• 한국수학사학회지
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• 제17권4호
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• pp.123-132
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• 2004

이 글에서는 20세기의 문제 해결의 역사에 대하여 개관하고, 21세기에 새로운 경향으로 주목받고 있는 모델링 관점에서의 수학 문제 해결에 대하여 알아보았다. 전통적인 문제 해결에서는 상황과 분리되어 있는 문제의 조건을 수학적 표현으로 바꾸는 번안 기술의 습득을 주요 관심사로 다루었다. 반면에, 모델링 관점에서 문제 해결은 해결할 필요가 있는 현실적인 문제 상황에서 출발하여 수학적인 정리 수단으로 재조직하고, 수학적 상황에서 문제를 해결하여 다시 실제 현상에 적용하는 과정을 따른다. 따라서, 학생들은 문제를 해결해 가는 과정에서 수학화를 경험하게 되고, 수학을 배우게 되는 이점이 있다.

• Advances in pediatric surgery
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• 제20권2호
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• pp.62-64
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• 2014

Gallbladder stones in children are not common without underlying hemolytic diseases or other risk factors like obesity. Ceftriaxone, a third generation cephalosporin, is known to make biliary precipitations that can be mistaken for biliary stones. We here report two children with biliary pseudolithiasis with different treatment modalities. One child was mistaken for symptomatic gallbladder stones and underwent elective laparoscopic cholecystectomy, while the other child, after thorough history taking on the ceftriaxone medication, was suspected of biliary pseudolithiasis and was treated conservatively. Both children had the history of usage of ceftriaxone in previous hospitals for infectious diseases. The ceftriaxone history of the first child was missed before the surgery. When gallbladder stones are found in children without any underlying diseases, specific history taking of the usage of ceftriaxone seems to be absolutely required. In this case, immediate interruption of the antibiotic could resolve the episode and avoid unnecessary surgical procedure.

• 한국기계가공학회지
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• 제10권6호
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• pp.63-69
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• 2011

This study analyzes stress, fatigue and vibration on main rotor and body of helicopter. The maximum stress is shown on adjoint part between body and main rotor at the lower position of main rotor. As the maximum displacement amplitude is happened at 4000Hz, there is no resonance and the state of helicopter becomes safe at hovering without the abnormal air current and the disabled rotor. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample History' with the average stress of 0MPa to $-10^5MPa$ and the amplitude stress of 0MPa to $8.539{\times}10^5MPa$, the possibility of maximum damage becomes 3%. This stress state can be shown with 5 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study by using the analysis of vibration and fatigue can be effectively utilized for safe and durable design of helicopter.

• 대한한의학원전학회지
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• 제32권3호
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• pp.85-102
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• 2019

Objectives : To examine the progression and presentation of King Jeongjo's Gyeok-ki(膈氣) symptoms during his reign. Methods : Based on recordings in the The Daily Records of Royal Secretariat of Joseon Dynasty related to Gyeok-ki(膈氣), characteristics of King Jeongjo's case was analyzed, then compared and examined against the political situation he was in. Results : During the 24 years of reign, King Jeongjo's Gyeok-ki(膈氣) developed in four stages; beginning stage with mild symptoms, intrinsic stage where it became the King's main disease, peak stage where symptoms intensified, and chronic stage where symptoms became rather manageable but the disease occurred regularly. Conclusions : From the year of accession to the year of death, King Jeongjo consistently complained of Gyeok-ki(膈氣), which seems to be strongly related to his family history and political situation.

• 대한건축학회논문집:계획계
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• 제35권6호
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• pp.69-80
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• 2019

This research focuses on 10 modern museums built in Europe near important cultural assets of UNESCO World Heritage level. This study aims to reveal the coexistence of European laminated history and contemporary architecture by considering various aspects of respecting the existing and maintaining their identity as modern buildings, using these cultural assets as a basic concept of planning while minimizing conflicts with the past. The four measures of respecting existing cultural heritage are arranged by showing respect by lowering oneself, sympathizing with others, preparing for harmony with modernity, and communicating by looking at. The measures that reveal the identity of modern buildings are confirmed by classifying them as modern and post-modern approaches, each with several options. Through this study, we have been able to extract useful lessons for us, as well, while the past and present coexist successfully, by taking history as a reliable guide to take a fresh leap from it, rather than as a solidified remnant of inertness.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제42권
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• pp.26.1-26.6
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• 2020

Background: Orofacial clefts (OFCs) comprise a wide range of malformations, including cleft lip, cleft palate, and cleft lip with cleft palate, which can vary in terms of etiology, severity, and disease burden. Objective(s): This study aimed to evaluate the correlation between various risk factors and orofacial cleft disorder spectrum in newborns. Study design: A total of 323 cases and 400 controls were enrolled in this study and evaluated in terms of the maternal history of abortion or miscarriage, child's sex, maternal and paternal age, maternal history of systemic disease, history of medication therapy during pregnancy, birth order, consanguineous marriage, and complications during pregnancy. Results: Analysis of the results suggested that consanguineous marriage, a maternal history of abortion/miscarriage, and complications during pregnancy could potentially increase the risk of OFCs in children (P < 0.05). However, the analyses revealed that the other variables could not potentially increase the risk of OFCs (P > 0.05). Conclusion(s): Multiple cofactors may simultaneously contribute to the formation of such abnormalities; therefore, a comprehensive, multidisciplinary care program is necessary to ensure a successful pregnancy period and the birth of a healthy newborn.