• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.966-970
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• 2011

The thermo-mechanical interaction between brake block and wheel tread during braking has been found to cause thermal crack on the wheel tread. Due to thermal expansion of the rim material, the thermal cracks will protrude from the wheel tread and be more exposed to wear during the wheel/block contact than the rest of the tread surface. The wheel rim is in residual compression stress when is new. After service running, the region in the tread has reversed to tension. This condition can lead to the formation and growth of thermal cracks in the rim which can ultimately lead to premature failure of wheel. In the present paper, the thermal cracks of railway wheel, one of severe damages on the wheel tread, were evaluated to understand the safety of railway wheel in running condition. The residual stresses for damaged wheel which are applied to tread brake are investigated. Mainly X-ray diffusion method is used. Under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, the reduction of residual stress is found to correlate well with the thermal crack initiation.

• 한국생산제조학회지
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• 제9권3호
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• pp.9-17
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• 2000

The use of ceramic inserts in steel forging tools offers significant technical and economic advantages over other materi-als of manufacture. These potential benefits can however only be realised by optimal design of the tools so that the ceramic insert are not subjected to stresses that led to their premature failure. In this paper the data on loading of the tools is determined from a commercial forging simulation package as the contact stress distribution on the die-workpiece interface and as temperature distributions in the die. This data can be processed as load input data for a finite-element die-stress analysis. Process simulation and stress analysis are thus combined during the design and a data exchange program has been developed that enables optimal design of the dies taking into account the elastic detections generated in shrink fitting the die inserts and that caused by the stresses generated in the forging process. The stress analysis of the dies is used to determine the stress conditions on the ceramic insert by considering contact and interference effects under both mechanical and thermal loads. Simulation results have been validated as a result of experimental investigation. Laboratory tests on ceramic insert dies have verified the superior performance of the Zirconia and Silicon Nitride ceramic insert in order to prolong maintenance life.

• 한국정밀공학회지
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• 제32권2호
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• pp.149-157
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• 2015

Ball and roller bearings are commonly used machine elements for supporting rotating motion about shafts in simple devices including bicycles, in-line skates, and electric motors, as well as in complex machines. Heat is generated by the friction in the bearings, which causes the temperature inside the bearing to increase. If the heat is not appropriately removed from the bearing, elevated temperatures may give rise to premature failure. It is, therefore, important to be able to calculate the temperature in the bearings due to friction.Here, we describe a method to estimate the frictional torque in bearings using an empirical formula developed using a method based on bearing analysis tool and the measured frictional torque in a spindle system. Thermal analysis of the spindle system including the bearings was achieved using the finite element method (FEM), and the bearing temperature was compared with measured data to verify the empirical formula.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.106-109
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• 2001

The use of ceramic inserts in hot extrusion dies offers significant technical and economic advantages over other forms of manufacture. These potential benefits can however only be realized by optimal design of the tools so that the ceramic inserts are not subjected to stresses that lead to their premature failure. In this paper, process simulation and stress analysis are thus combined during the design, and a data exchange program has been developed that enables optimal design of the dies taking into account the elastic deflections generated in shrink fitting the die inserts and that caused by the stresses generated in the process. The stress analysis of the dies is used to determine the stress conditions on the ceramic insert by considering contact and interference effects under both mechanical and thermal loads. The results are compared with the experimental ones for verification.

• 대한치과의사협회지
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• 제10권2호
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• pp.121-128
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• 1972

14 patients, whose were attacked pain dysfunction syndrome of temporomandibular joint in Dental College Infirmary, Seoul National University from June 1970 to Dec. 1971, were examined regarding to clinical observation and electromyographical analysis. This paper established the followings: 1. Especially young female was more frequently attacked by pain dysfunction syndrome of Temporomandibular joint. 2. It is suggested that most of joint pain was occurred initially in opening mouth and forcible bite, and left side is more attacked than right side. 3. It was possible that this dysfunction can be occurred by open-bite, premature contact and ill-fitting prosthetic restoration. 4. Hoby, habit and bruxism as causal factors are not markedly related with this dysfunction. 5. Pain attacked regions, in most patients, are preauricular, joint itself, infra-auricular, cervical and external auditory meatus region. 6. In electromyographical studis, the musle activities of affected side of pain dysfunction syndrome are more strong than that of opposite side.

• 한국산학기술학회논문지
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• 제17권3호
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• pp.599-610
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• 2016

본 연구는 미숙아와 어머니를 대상으로 캥거루 케어 효과를 비교하기 위해 수행된 체계적 문헌고찰 및 메타분석 연구이다. 2015년 2월까지 출간된 무작위 임상실험연구를 검토하였으며, 국내문헌은 연구설계수준에 따른 제한 없이 비무작위 임상실험연구를 포함하였다. 문헌은 Ovid-Medline, CINAHL, PubMed와 국내 DB인 KoreaMed, 국립중앙도서관, 국회도서관, 국가과학기술전자도서관, KISS, RISS, 한국의학논문을 통해 ((kangaroo OR KC OR skin-to-skin) AND (care OR contact)) AND (infant OR preterm OR Low Birth Weight OR LBW), ((캥거루 OR 캉가루 OR 캉가루식) AND (케어 OR 간호 OR 관리 OR 돌보기 OR 피부접촉)) 등을 주요어로 조합하여 검색하였으며, 선택배제과정을 거쳐 최종 25편(n=3051)의 문헌이 분석에 포함되었다. 문헌에 대한 질평가는 SIGN에서 제시한 평가도구를 사용하였으며, 질평가 결과는 16편에서 ++, 9편에서 +로 평가되어 전반적으로 비뚤림 위험은 없는 것으로 판단하였다. 미숙아를 대상으로 한 캥거루 케어의 효과에 대한 메타분석 결과, 미숙아 사망률, 중증 감염/패혈증 발생률, 저체온 발생률, 병원입원기간, 모유수유율, 수면상태, 어머니의 불안, 어머니 역할수행 자신감, 어머니 역할수행 만족도에서 통계적으로 유의한 효과가 있었으며, 고체온 발생률, 미숙아의 성장발달(신장, 체중), 모아애착, 우울, 스트레스는 유의미한 차이가 없었다. 국내에서 캥거루 케어에 대한 무작위 임상실험연구 수가 적어 효과크기에 대한 확증적 결과를 얻는 데에는 다소 제한이 있었으므로 향후 이와 관련된 무작위 임상실험연구의 효과검증에 대한 노력이 지속적으로 이루어져야 할 것으로 사료된다.

• 여성건강간호학회지
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• 제6권4호
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• pp.549-565
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• 2000

Comprehensive review of the literature was conducted to determine 1) selected risk factors and its impact that affect pregnancy outcome such as smoking, alcohol consumption, and substance abuse 2) these factors can facilitate future strategies for health promotion and prevention for both pregnant women and fetus. Review of literature were extracted from searching MEDLINE(1966 - Oct. 2000). CINAHL (1982 - Oct. 2000) and the domestic literature. The following factors were identified: 1. The effects of risk behaviors on pregnancy. ${\cdot}$Maternal smoking was associated with the occurrence of premature or LBW delivery, fetal growth retardation, extremities defects, heart defects and sudden infant death syndrome. ${\cdot}$Maternal alcohol consumption was associated with spontaneous abortion, premature or LBW delivery, morphologic/neurologic problems, especially fetal alcohol syndrome. ${\cdot}$Heroin was associated with withdrawal after birth in which were born to heroine addicts for gestational age and lung maturation in animal studies. ${\cdot}$Cocaine was associated with spontaneous abortion, abruptio placenta and a poor response to environmental stimuli. ${\cdot}$So far, the effects of caffeine on pregnancy was controversial, but severe caffeine consumption was associated with premature or LBW delivery, spontaneous abortion, still birth and dystocia. 2. Intervention methods and its effects identified were as follows ${\cdot}$Conducted intervention for smoking, alcohol and drug consumption were single or combined. ${\cdot}$Intervention methods were counseling, phone contact, mailing, use of educational videotape, booklet, support person and alternatives such as nicotine patch. ${\cdot}$The interventions increased the rates of smoking cessation during pregnancy and awareness of the risk of drug consumption, and decreased amount of alcohol consumption. ${\cdot}$The intervention outcome found positive effect on birth weight and length. 3. Our recommendations were as follows ${\cdot}$The personal and social cognition should be enhanced through education and the mass media. ${\cdot}$It's necessary to educate and give information of preconceptional care, planned pregnancy and early prenatal care for optimal pregnancy outcome. ${\cdot}$It's necessary to develop comprehensive assessment tool which is reliable and valid on smoking, alcohol consumption and substance abuse to identify supportive or interventional program.

• 대한치과보철학회지
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• 제58권4호
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• pp.328-334
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• 2020

치과의사는 악간관계기록 오류로 인해 발생하는 교합오차를 줄이기 위해 진료실재부착을 시행한다. 진료실재부착으로 수정된 의치를 사용하면 일반적으로 통증이 감소하고 의치 사용이 편해지며 더 편하게 저작할 수 있다고 한다. 하지만 이러한 평가는 환자의 주관적인 평가이므로 본 연구에서는 실험적인 지표를 통해 진료실재부착의 효과를 확인하고자 하였다. 7명의 환자를 대상으로 전치부에서 1 - 2 mm의 공간이 있도록 중심위 악간관계를 채득하여 진료실재부착을 시행한 후 미끄러짐 유무를 확인하였으며, 압력감지센서로 교합력을 측정하였고 실리콘인기재로 교합면적을 측정하였다. 진료실재부착후 교합압의 변화는 없었으나 교합면적 증가와 함께 접촉 후 미끄러짐이 줄어드는 것을 확인할 수 있었다. 진료실재부착을 시행하면 조기접촉이 감소하고 교합면적이 증가하므로 시행하는 것이 필요하다.

• 한국정밀공학회지
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• 제28권5호
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• pp.537-542
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• 2011

The thermo-mechanical interaction between brake block and wheel tread during braking has been found to cause thermal crack on the wheel tread. Due to thermal expansion of the rim material, the thermal cracks will protrude from the wheel tread and be more exposed to wear during the wheel/block contact than the rest of the tread surface. The wheel rim is in residual compression stress when is new. After service running, the region in the tread has reversed to tension. This condition can lead to the formation and growth of thermal cracks in the rim which can ultimately lead to premature failure of wheel. In the present paper, the thermal cracks of railway wheel, one of severe damages on the wheel tread, were evaluated to understand the safety of railway wheel in running condition. The residual stresses for damaged wheel which are applied to tread brake are investigated. Mainly X-ray diffusion method is used. Under the condition of concurrent loading of continuous rolling contact with rails and cyclic frictional heat from brake blocks, the reduction of residual stress is found to correlate well with the thermal crack initiation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제27권6호
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• pp.570-575
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• 2001

This study evaluated the short-term outcome of treating fractures of the mandible with bioabsorbable plates. Thirty-four fractures of the mandible in 27 patients were treated by open reduction and internal fixation using bioabsorbable plates and 2.4-mm, 2.0-mm, and 1.5-mm pre-tapped screws. The duration of intermaxillary fixation ranged from 0 to 23 days, with a mean of 5.3 days. Patients were evaluated for complications during the follow-up period, which ranged from 2 to 18 months. Five patients(18.5%) experienced complications. These included infection (four patients), and premature occlusal contact(one patient). Except for one case, all complications were minor and adequately managed with incision and drainage, elastic traction, and medication. Delayed infection (osteomyelitis) developed in a symphysis fracture and was treated by saucerization and antibiotics. The fracture line subsequently showed complete consolidation. Bioabsorbable plates can be selectively used for internal fixation in mandibular fractures with the advantage that they do not need to be removed.