• Computers and Concrete
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• 제31권3호
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• pp.207-221
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• 2023

In this investigation, the interaction between opening space and neighboring joint has been examined by experimental test and Particle flow code in two dimension (PFC2D) simulation. Since, firs of all PFC was calibrated using Brazilian experimental test and uniaxial compression test. Secondly, diverse configurations of opening and neighboring joint were provided and tested by uniaxial test. 12 rectangular sample with dimension of 10 cm*10 cm was prepared from gypsum mixture. One quarter of tunnel and one and or two joint were drilled into the sample. Tunnel diameter was 5.5 cm. The angularities of joint in physical test were 0°, 45° and 90°. The angularities of joint in numerical simulation were 0°, 30°, 60°, -30°, -45°, -60° and its length were 2cm and 4cm. Loading rate was 0.016 m/s. Tensile strength of material was 4.5 MPa. Results shows that dominant type of crack which took place in the model was tensile cracks and or several shear bands develop within the model. The Final stress is minimum in the cases where oriented angle is negative. The failure stress decrease by decreasing the joint angle from 30° to 60°. In addition, the failure stress decrease by incrementing the joint angle from -30° to -60°. The failure stress was incremented by decreasing the number of notches. The failure stress was incremented by decreasing the joint length. The failure stress was incremented by decreasing the number of notches. Comparing experimental results and numerical one, showed that the failure stress is approximately identical in both conditions.

• Journal of Yeungnam Medical Science
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• 제15권2호
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• pp.316-324
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• 1998

This study was performed to evaluate the clinical features and treatment results on 55 temporomandibular disorder patients who had treated by conservative treatment using occlusal splint. The results were as follows; 1. The ratio of men to women was about 1:2.2 and most of the patients were second and third decades. 2. Pain was the most frequent symptom, followed by clicking and mouth opening limitation. 3. The number of acute and chronic groups on the basis of 6 months duration of symptoms were similar. 4. Most of patients had Angle's Class 1 molar relationships(78.2%), followed by Class 3 and Class 2. 5. Centric Relation splints were used alone for treatment of 34 patients and 21 patients were treated with Centric Relation splints and Anterior Repositioning splints. The treatment duration of the patients who had complained pain was average 9.8 weeks and 6 patients of them had slight pain continuously during follow-up. 6. Eleven patient's maximum mouth opening who had mouth opening limitation was improved from 30. 7mm to 43.0mm during procedures.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.410-423
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• 2019

Fire suppression using a water mist nozzle directly above an n-Heptane pool in a fire compartment with a door opening was numerically investigated using the Fire Dynamics Simulator (FDS) for the purpose of application in nuclear power plants. Input parameters for the numerical simulation were determined by experimental measurements. Water mist was activated 10 s after the fire began. The sensitivity analysis was conducted for three input parameters: total number of cubic cells of 6032-2,926,400, droplets per second of 1000-500,000, and extinguishing coefficient of 0-100. In a new simple calibration method of this study, the extinguishing coefficient yielding the fire suppression time closest to that measured by experiments was found for use as the FDS simulation input value. When the water mist jet flow made contact with the developed fire, the heat release rate instantaneously increased, and then rapidly decreased. This phenomenon occurred with a displacement of the flame near the liquid fuel pool. Changing the configuration of the door opening with different aspect ratios and opening ratios had impact on the maximum value of the heat release rate due to the flame displacement.

• 한국대기환경학회지
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• 제24권2호
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• pp.153-161
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• 2008

The guidelines for indoor air quality of public transportations such as subway, train and bus was presented by Korean Ministry of Environment last end of year 2006 based on the great consequence of indoor air quality in daily life. Two main parameters, carbon dioxide($CO_2$) and particulate matters smaller than $10\;{\mu}m(PM_{10})$, were selected as index pollutants for the management of indoor air quality. The former pollutant, $CO_2$, is regarded as index of ventilation status and the major source of $CO_2$ in the train or subway is the exhalation of passengers. It is publically perceived that the high $CO_2$ concentration in a crowded subway will be reduced and ventilated with outdoor air by door-opening taken every 2 or 3 minutes when the train stops each station. However, there has not been any scientific proof and quantitative information on the effect of door-opening on the $CO_2$ reduction by ventilation with outdoor air. In this study, $CO_2$ concentration and number of passengers were measured at each station on the 3 lines of Korail metropolitan subway. In order to evaluate the effect of $CO_2$ reduction by door opening, the theoretical approach using the $CO_2$ balance equation was performed. By comparing the predicted data with monitoring one, the optimum $CO_2$ dilution factor was determined. For the first time, it was quantified that about 35% of $CO_2$ concentration in the subway indoor was removed by the door-opening at each station.

• 대한구순구개열학회지
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• 제7권2호
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• pp.133-139
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• 2004

Congenital bilateral idiopathic hyperplasia of the coronoid processes presents with limited mouth-opening without visible maxillofacial deformity or temporomandibular joint dysfunction / disorder. According to Blanchard et al and McLoughlin et al, it was lnitially described in 1853 by Langenbeck, and the first cases were reported by Holmes in 1956. Since then, there have been regular reports of a certain number of cases. In 1995, McLoughlin et al recorded 79 published cases of bilateral hyperplasia of the coronoid processes. Among them, Fabie et al have found only 3 published cases relating to children younger than 8 years, and have presented the first case of objectively diagnosed restricted mouth opening from birth by pediatricians. Authors have experienced 2 child patients with mouth opening limitation who was diagnosed congenital bilateral idiopathic hyperplasia of the coronoid processes without any other TNJ morphology in Dept of Oral and Maxillofacial surgery, Seoul National University Dental Hospital in 2004. Coronoidectomy was performed and postoperative active mouth opening exercise is indicated. Authors report 2 cases of congenital bilateial idiopathic hypeiplasia of the coronoid processes with literature liview.

• 의료법학
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• 제15권2호
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• pp.345-366
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• 2014

Because the health care or medical sector has such characteristics as publicity, professionality, and exclusivity, it cannot be left to the free market system. As a consequence, the state has restricted the establishment of medical institutions in order to protect the life and health of people. Also, the medical law has regulated to permit the establishment of medical institutions by only medical personnel and a few corporate bodies and to ban the establishment of medical institutions under disguised ownership as well as double opening of medical institutions by medical personnel. Nevertheless, there are still many cases that non-medical personnel have dominantly established medical institutions under disguised ownership of other medical personnel or nonprofit corporation. Because they are willing to recover their investment costs as soon as possible, these illegally established medical institutions are likely to make patients undergo unnecessary tests or to perform the excessive treatments and, as a result, are likely to cause infringement on the health and lives of the people. In addition, even if the misconduct is uncovered, the rate at which the costs already paid is very low and, as a result, the damages are straightly connected to the people's loss. On the other hand, there are also increasing number of cases that medical personnel or nonprofit corporations are establishing medical institutions against the medical law regulations. The examples of this illegality are also the double opening of medical institutions and the establishment of medical institutions under disguised ownership by medical personnel or nonprofit corporations. And the damages in these cases may not differ from those in the above cases. In this study, regarding medical law regulations restricting opening a medical institution, I will review the intent of those regulations, the type of violations and criminal punishments, and the possibility of recovery from unlawful profit by the National Health Insurance Act. And then, I would like to find a way for rational improvement of each.

• 대한치과보철학회지
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• 제34권2호
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• pp.277-289
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• 1996

The purpose of this study was to compare the amount of the vertical pin opening of dentures processed by the conventional compression method & the injection-processing method. The articulating ribbon and T-Scan system were used to determine the changes in tooth contacts and the correlation between the changes in tooth contacts and the amount of the vertical pin opening after processing was analyzed statistically. The obtained results were as follows. 1. The amounts of the vertical pin opening were 0.75mm, 0.31mm for conventional compression method and injection-pressing method, respectively. The difference between the two methods was highly significant on the basis of t test statistics(p<0.05). 2. The total number of contact points recorded by articulating ribbon after processing was decreased to 48%, 72%, of that before processing for conventional compression method and injection-pressing method, by T-Scan system, 39%, 53%, respectively. 3. The mean values for the number of contacts points per tooth recorded by articulating ribbon after processing were 1.6 for the second molar, 2.2 for the first moalr, 0.4 for the second premolar, 0.6 for the first premolar in conventional compression method, and 2, 3.2, 1.2, 0.8 in injection-pressing method. 4. The correlation between the reduction of contact points and the amount of the pin opening after processing was not significant. 5. The mean values for the number of contact points per tooth recorded by T-Scan system after processing were 1.25, 1.4, 0.7, and 0.55 at the second molar, the first molar, the second premolar, and the first premolar in conventional compression method, and 1.45, 2.1, 1.0, 0.75 in injection method, respectively. 6. The correlation between the number of contact points by using articulating ribbon and T-Scan system after processing was not significant in both methods.

• Journal of Oral Medicine and Pain
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• 제26권2호
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• pp.133-146
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• 2001

This study was performed to predict the conservative treatment outcome of TMD patients by investigating the prognostic factors ; symptom duration, history of previous treatment, history of previous medication, history of trauma, disability of daily activity, severity of pain, noise, limitation of mouth opening(LOM) and maximum comfortable opening(MCO). Two hundreds and fifty-four subjects were selected for this study among the TMD patients who had visited the Dept. of Oral Medicine BNUH and been treated conservatively with medication, physical therapy, behavioral treatment, and splint therapy from 1991 to 2000. The subjects were divided into two groups improved or unimproved according to the treatment response following six months of conservative treatment. Those who showed less than 1 on NAS for pain, TMJ noise, and opening limitation belonged to the improved group and those who showed more than 2 on NAS belonged to the unimproved group. The two groups were compared with respect to symptom severity, number of diagnosis, history of trauma, previous treatment, previous medication, and disability of daily activity. A prognostic equation with the factors revealed to be significantly related to the prognosis of conservative treatment was obtained. The obtained results were as follows ; 1. In improved group, mean duration of history was 12 months, mean treatment duration of a patient was 4 months an mean number of treatment was about 10 times. In other words, in unimproved group, mean duration of history was 27.4 months, mean treatment duration of patient was 10.5 months and mean number of treatment was 19 times. 2. In unimproved group, multiple diagnosis, chronicity, disability of daily activity were significantly greater than that of the improved group. 3. Patients in unimproved group revealed severe noise at first visit and smaller maximum comfortable opening comparatively. 4. Prognostic factors such as duration of treatment, number of treatment, multiplicity, and chronicity and disability of daily activity showed a significant relation in prediction of improvement. 5. Prognostic equation with significant variables is as follows ; Y = 1.984 - 0.251Noise + 0.068MCO - 0.673Multiplicity. - 0.958Chronicity - 0.065Disability. Classification accuracy of 70.3 %, sensitivity of 71.4% and specificity of 66.7% were shown. 6. Prognostic equation with all factors is as follows : Y = 1.599 - 0.038Pain - 0.256Noise - 0.006Limitation + 0.068MCO - 0.580Multiplicity - 1.025Chronicity - 0.720Disability - 0.329Medication - 0.087Treatment + 0.740Trauma. Classification accuracy of 70.3 %, sensitivity of 73% and specificity of 64.3% were shown. 7. Prognostic value of the improved group with significant factors was $1.0446{\pm}1.0726$ and prognostic value of the unimproved group with significant factors was $-0.013{\pm}1.0146$. Prognostic value of the improved group with all factors was $1.0465{\pm}1.0849$ and prognostic value of the unimproved group with all factors was $-0.057{\pm}1.0611$.

• 대한치과보철학회지
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• 제42권6호
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• pp.628-640
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• 2004

Statement of problem. Wear as a result of repeated closing/opening cycles may decrease the friction coefficient of screw head, threads, and other mating components and, consequently, resistance to opening gradually decreases. It may cause screw loosening, which is one of the most common failures in implant prosthesis. Purpose. The purpose of this study is to evaluate the changes on the head and thread surface of the abutment screws after repeated closing and opening through the examination of tested screws in SEM(scanning electron microscope). Materials and methods. Five species of abutments were selected (3i-three, Avana-two) respectively by two pieces. The implant fixtures were perpendicularly mounted in liquid unsaturated polyesther(Epovia, Cray Valley Inc.) with dental surveyor. Each abutment was secured to the implant fixture by each abutment screw with recommended torque value using a digital torque controller. The abutment screws were repeatedly tightened and removed 20 times with a digital controller. FESEM (field emission scanning electron microscope, Netherland, Phillips co., model:XL 30 SFEG) was used to observe changes of each part caused by repeatedly closing/opening expeiment. First, the Photomicrographs of pre-test screws provided by each manufacturer were taken. The changes of each screw were investigated after every fifth closing and opening experiment with FESEM. Scaning electron microscope photomicrographs of each screw were taken four times. Results. As the number of closing and opening was increased, the wear or distortion of hexed or squared slot that contacted with the driver tip was more severely progressed. Wear or distortion of hexed slot was more severe than that of squared slot and it was more remarkable in the titanium screw than in the gold screw. All the tested screws showed that the width in the crest of their screw thread decreased gradually as the test was proceeded. Conclusions. Conclusively, we recommend the clinical use of gold screw, a periodic exchanges of abutment screws and avoiding repeated closing/opening unnecessarily. We also suggest a more careful manipulation of the abutment screw and screw-driver and using of abutment screw with an acute-angled slot design rather than an obtuse-angled one. Finally, it is suggested that the new slot design and the surface treatment for enduring wear or distortion should be devised.

• 한국재난정보학회 논문집
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• 제16권3호
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• pp.479-492
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• 2020

연구목적: 본 연구의 목적은 우리나라 수도권을 대상으로 권역별 특성이 인구이동에 미치는 영향을 분석하는 것이다. 연구방법: 이를 위해 수도권의 66개 기초지자체는 2010~2016년 인구이동자료 분석을 통해 3개의 권역으로 구분하고, 단계적 회귀분석기법을 적용하여 권역 내부의 인구이동 결정요인과 권역 간 인구이동 결정요인을 파악하였다. 연구결과: 주요 분석결과로 수도권 전 지역에서의 인구이동에서는 지역의 아파트 수 증가율, 단독·다세대주택 증가율, 고용자 수 증가율, 제조업체 증가율, 지식·문화·여가산업 증가율, GRDP증가율, 지하철역 신규개통이 중요하다는 것이 확인되었다. 특히 아파트 수 증가율, 지식·문화·여가산업 증가율, GRDP 증가율, 지하철 역 신규개통은 인구유입을 늘리는데 긍정적으로 작용하였다. 결론: 권역별로 지식·문화·여가산업 증가율이 1권역의 인구유입에 크게 기여했으며, 2권역에서는 지하철역 신규개통과 GRDP증가율이 주요 요인인 것으로 나타났다. 아파트 수 증가율과 지하철역 증가율은 3권역에서 주요 요인으로 작용하였다.