• 한국해양환경ㆍ에너지학회지
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• 제14권2호
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• pp.138-145
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• 2011

이 논문에서는 Monte Carlo method를 이용하여 주어진 파랑스펙트럼에서 위상차를 임의의 수 (random number)를 발생시켜 파형의 시계열 자료를 시뮬레이션하여 freak wave의 발생 특성을 살펴보았다. 여러 가지 상태의 해상상태를 스펙트럼법에서 정의한 유의파고 $H_s$와 유의파첨도 $S_s$의 조합을 이용해서 표시하였다. 유의파첨도가 동일한 경우에는 $H_s$가 커질수록 freak wave 발생 확률이 낮아지며 $H_s$가 동일한 경우 유의파첨도가 커질수록 freak wave 발생확률이 높아진다. 주어진 해상상태에서 최대파고 $H_{max}$의 평균은 $S_s$의 값이 증가함에 따라 조금씩 증가한다. 그러나 freak wave의 평균파고는 $S_s$에 관계없이 일정한 값을 가지며 freak wave 파고의 평균은 $H_s$의 2배가 된다. $S_s$가 일정한 경우 $H_s$가 증가하면 파형의 평균 첨도(kurtosis)가 증가한다. 그러나 $H_s$가 일정한 경우 $S_s$가 증가하면 첨도의 평균은 감소한다. Freak wave 발생 기준인 이상지수(Abnormality index, AI)의 평균값은 $H_s$와 $S_s$에 관계없이 2.11 정도의 값을 가지며 AI의 최대값은 2.5-3.0 사이의 값을 가진다. 따라서 Linear focusing에 의해서 발생한 freak wave의 AI의 상한 값은 3.0 정도라고 추정할 수 있다.

• Nuclear Engineering and Technology
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• 제55권2호
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• pp.408-420
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• 2023

Beryllium oxide (BeO) is being re-emphasized and utilized in Micro Modular Reactors (MMR) because of its prominent nuclear and high temperature properties in recent years. The implications of the research about effects of neutron irradiation on the microstructure and properties of BeO are significant. This article comprehensively reviews the effects of neutron irradiation on BeO and proposes the maximum permissible neutron doses at different temperatures for BeO without cracks in appearance according to the data in the previous literature. This maximum permissible neutron dose value has important reference significance for the experimental study of BeO. The effects of neutron irradiation on the thermal conductivity and flexural strength of BeO are also discussed. In addition, microstructure evolution of irradiated BeO during post-irradiation annealing is summarized. This review article has important implications for the application of BeO in MMR.

• The Journal of Korean Physical Therapy
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• 제22권6호
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• pp.59-63
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• 2010

Purpose: Driving a car is an essential component of daily life. For safe driving, each driver must perceive sensory information and respond rapidly and accurately. Brake response time (BRT) is a particularly important factor in the total stopping distance of a vehicle, and therefore is an important factor in traffic accident prevention research. The purpose of the current study was (1) to compare accelerometer. BRTs analyzed by three different methods and (2) to investigate possible correlations between accelerometer-BRTs and foot switch-BRTs, which are measured method using a foot switch. Methods: Eighteen healthy subjects participated in this study. BRT was measured with either a tri-axial accelerometer or a footswitch. BRT with a tri-axial accelerometer was analyzed using three methods: maximum acceleration time, geometrical center, and center of maximum and minimum acceleration values. Results: Both foot switch-BRTs and accelerometer-BRTs were delayed. ANOVA for accelerometer BRTs yielded significant main effects for axis and analysis, while the interaction effect between axis and analysis was not significant. Calculating the Pearson correlation between accelerometer-BRT and foot switch-BRT, we found that maximum acceleration time and center of maximum and minimum acceleration values were significantly correlated with foot switch-BRT (p<0.05). The X axis of the geometrical center was significantly correlated with foot switch-BRTs (p<0.05), but Y and Z axes were not (p>0.05). Conclusion: These findings suggest that the maximum acceleration time and the center of maximum and minimum acceleration value are significantly correlated with foot switch-BRTs.

• PNF and Movement
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• 제19권1호
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• pp.105-113
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• 2021

Purpose: The purpose of this study was to investigate the effect of trunk-stabilization training using stabilizing reversal and rhythmic stabilization techniques of PNF on trunk muscle strength and respiratory function in elderly stroke patients. Methods: There were 26 stroke patients included in the study. Patients were divided into two groups, and all patients performed exercise 30 min five times per week for six weeks. The experimental group performed trunk stability exercise using stabilizing reversal and rhythmic stabilization techniques of PNF, and the control group performed flexibility and strength training. Trunk muscle strength, forced vital capacity, maximum inspiratory pressure, and maximum expiration pressure were measured to determine the changes after the intervention. For statistical processing, a paired t-test was performed within the group, and the value after intervention was performed as an independent t-test to find out the difference between the two groups. Results: In the experimental group, all of the trunk muscle strength, forced vital capacity, maximum inspiratory pressure, and maximum expiration pressure showed significant differences according to the intervention. In the control group, there were statistically significant differences in trunk muscle strength and forced vital capacity, but the maximum inspiratory pressure and the maximum expiration pressure did not show any statistical change. Conclusion: From these results, it can be seen that the trunk stability exercises that use the proprioceptive neuromuscular promotion method of stable reversal and rhythm stabilization can be a good intervention for the respiratory function of stroke patients.

• 대한물리의학회지
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• 제17권2호
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• pp.95-100
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• 2022

PURPOSE: The purpose of this study was to compare the effect of depending on the location of applying chest expansion resistance exercise on the respiratory muscle strength stroke patients, and to suggest more effective interventions to improve respiratory function in stroke patients in clinical practice. METHODS: A total of 30 subjects were selected and divided into two groups, and chest cage extension resistance exercise was applied to the sternum and rib cage, respectively, and performed for 4 weeks, 3 times a week, for 20 minutes. In order to compare the general characteristics of the study subjects and the homogeneity of the group, the pre-experimental values were analyzed using the independent sample t-test. Paired-sample t-test was used for pre-post value comparison of maximum inspiratory pressure and maximum expiratory pressure in each group. Statistical significance was set to .05. RESULTS: Both the sternum application group and the rib cage application group showed a significant difference in the maximum inspiratory pressure according to the intervention. Also, there was a statistically significant difference in the maximum expiratory pressure in the sternum application group. CONCLUSION: As breathing exercise is important for stroke patients, based on the results of this study, if therapists perform sternal extension resistance exercise or rib extension resistance exercise according to the patient's condition and environment, it can help the breathing function of stroke patients.

• 한국환경과학회지
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• 제28권7호
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• pp.617-627
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• 2019

This study investigated the relationship between heat-related illnesses obtained from healthcare big data and daily maximum temperature observed in seven metropolitan cities in summer during 2013~2015. We found a statistically significant positive correlation (r = 0.4~0.6) between daily maximum temperature and number of the heat-related patients from Pearson's correlation analyses. A time lag effect was not observed. Relative Risk (RR) analysis using the Generalized Additive Model (GAM) showed that the RR of heat-related illness increased with increasing threshold temperature (maximum RR = 1.21). A comparison of the RRs of the seven cities, showed that the values were significantly different by geographical location of the city and had different variations for different threshold temperatures. The RRs for elderly people were clearly higher than those for the all-age group. Especially, a maximum value of 1.83 was calculated at the threshold temperature of $35^{\circ}C$ in Seoul. In addition, relatively higher RRs were found for inland cities (Seoul, Gwangju, Daegu, and Daejeon), which had a high frequency of heat waves. These results demonstrate the significant risk of heat-related illness associated with increasing daily maximum temperature and the difference in adaptation ability to heat wave for each city, which could help improve the heat wave advisory and warning system.

• 대한영양사협회학술지
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• 제4권1호
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• pp.76-87
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• 1998

The purpose of this study was to examine the nutrition knowledge and attitude of the elderly for developing nutrition education program. The nutrition knowledge test was consisted of nutrition, nutrients, weight control, food safety, and shopping tips by developing the table of specifications. The nutrition attitude test was comprised of seventeen questions for invention, self-efficacy, control, and outcome expectation. A total of 140 elderly living at home responded to both nutrition knowledge and attitude test. According to the results of nutrition knowledge test, the mean was 13.3 at the maximum 18 points and 51.4% respondents got more than 14 points. Significant differences were found with age (p<0.05, $x^2$=21.46), charge of income (p<0.05, $x^2$=8.86) and monthly expenses(p<0.05, $x^2$=22.95). The results of nutrition attitude test showed that the mean value of 40.89 points at the maximum 51 points and 58.6% of respondents rated more than 40.89 points. In exploring the relationship between the demographic variables(sex, age, educational level, and monthly expenses) and for attitude concepts, a significant correlation was found. Correlation among the knowledge for nutrition, nutrients, and the attitudes for nutrition was significant(p<0.05).

• 산업기술연구
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• 제23권A호
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• pp.69-81
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• 2003

Numerical analysis is important for the design, construction and maintenance of large caverns. The rock mass contains generally discontinuities such as faults, joints and fissures. The mechanical behavior and geometric characteristics of these discontinuities would have a significant impact on the stability of the caverns. In this research the Distinct Element Method(DEM) was used to analyze the structural stability of the large cavern. The Barton-Bandis Joint Model (B-B J.M) was used as a constitutive model for the joint. In addition, two different cases 1) analysis with a support system and 2) analysis with no support system, were analyzed to optimize a support system and to investigate reinforcing effects of a support system. The most significant parameters of in-situ stress, JRC of in-situ natural joints, and spatial distribution characteristics of discontinuities were acquired through field investigation. Displacement (horizontal, joint shear), maximum joint opening, maximum and minimum principal stresses, range of relaxed zone, rockbolt axial forces and shotcrete stresses were calculated at each excavation stage. As a result of analysis the calculated values proved to be under the allowable value Rockbolts also proved to be an efficient support measure to control joint shear displacement which had significant effects on extending the relaxed zone. As a consequence, the structural stability of the cavern was assured with an appropriate support system.

• 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 $-0.057{\pm}1.0611$.

• The Journal of Advanced Prosthodontics
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• 제6권2호
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• pp.103-108
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• 2014

PURPOSE. The occlusal splint has been used for many years as an effective treatment of sleep bruxism. Several methods have been used to evaluate efficiency of the occlusal splints. However, the effect of the occlusal splints on occlusal force has not been clarified sufficiently. The purpose of this study was to evaluate the effect of occlusal splints on maximum occlusal force in patients with sleep bruxism and compare two type of splints that are Bruxogard-soft splint and canine protected hard stabilization splint. MATERIALS AND METHODS. Twelve students with sleep bruxism were participated in the present study. All participants used two different occlusal splints during sleep for 6 weeks. Maximum occlusal force was measured with two miniature strain-gage transducers before, 3 and 6 weeks after insertion of occlusal splints. Clinical examination of temporomandibular disorders was performed for all individuals according to the Craniomandibular Index (CMI) before and 6 weeks after the insertion of splints. The changes in mean occlusal force before, 3 and 6 weeks after insertion of both splints were analysed with paired sample t-test. The Wilcoxon test was used for the comparison of the CMI values before and 6 weeks after the insertion of splints. RESULTS. Participants using stabilization splints showed no statistically significant changes in occlusal force before, 3, and 6 weeks after insertion of splint (P>.05) and participants using Bruxogard-soft splint had statistically significant decreased occlusal force 6 weeks after insertion of splint (P<.05). There was statistically significant improvement in the CMI value of the participants in both of the splint groups (P<.05). CONCLUSION. Participants who used Bruxogard-soft splint showed decreases in occlusal force 6 weeks after insertion of splint. The use of both splints led to a significant reduction in the clinical symptoms.