• 대한통합의학회지
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• 제6권1호
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• pp.91-98
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• 2018

Purpose : The aim of this study is to determine changes to the thickness of core muscles, e.g., transversus abdominis (TrA), external oblique (EO), and internal oblique (IO), after plank and Kegel exercises and to compare the effects of the two exercise methods. Method : The study divided men and women in their 20s into two groups, Kegel and plank, by randomly allocating 30 males and 30 females to the targeted groups. To achieve the purpose of this study, we examined the thickness of core muscles after the participants performed plank or Kegel exercises. Results : 1. In the Kegel group, abdominal muscle thickness increased with time, and there was a statistically significant difference in the thickness of the TrA. 2. In the plank group, abdominal muscle thickness increased with time, and there was a statistically significant difference in the thickness of the TrA. 3. After the experiment, muscle thickness of the abdominal muscles in the plank exercise group were higher, but there was no significant difference between the Kegel exercise group and the plank exercise group. Conclusion : Both plank and Kegel exercises are recommended for core muscle stabilization, and based on the results of this study, Kegel exercise is either used as a core stabilizing exercise or as a plank exercise for the weaker patients or women.

• 한국가스학회지
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• 제16권4호
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• pp.16-22
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• 2012

용접기술의 발달과 더불어 기계, 교량, 선박 그리고 가스설비 등의 제작공정을 위하여 용접의 이용이 증가하고 있다. 따라서 그들의 용접 구조물 제작을 위하여 높은 생산성과 안전설계를 고려하는 용접 법을 개발하는 것이 요구되고 있다. 본 연구에서는 재료 두께, 용접층수, 하중 방향 그리고 토우부의 노치 반경과 관련하여 완전 용입 십자형 필릿 용접부의 피로강도 및 피로수명의 특성에 대하여 기초적으로 고찰하였다. 대부분의 피로파괴는 십자형 필릿 용접의 토우부에서 발생하였다. 피로강도 및 피로수명은 토우 부의 노치 반경과 플랭크 각에 의한 응력집중의 영향을 받고 있다. 토우부의 금속이 다층 용접에 의하여 어닐링 되고 확산 되었으며 그 결과 침상 페라이트 조직이 형성되어 피로강도와 피로수명을 향상시켰다.

• 한국압력기기공학회 논문집
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• 제15권1호
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• pp.62-70
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• 2019

The APR1400 reactor may be operated for a long time under high temperature and pressure conditions, causing damage to the stud holes and causing stud bolts and holes to stick. The present practice is to manually remove the anti-sticking agent and foreign matter remaining in the APR1400 reactor stud hole and to visually check the surface condition of the thread to check the damage status of the threads. In the case of the APR1400 reactor stud holes, manually cleaning the threads increases the risk of radiation exposure and operator's fatigue. To avoid this, the autonomous mobile robot is used to automatically clean the reactor stud holes. The purpose of this study is to optimize the cleaning performance of the mobile robot by looking at the behavior of the surface roughness of the stud surface cleaned by the brush attached to the mobile robot due to changes in brush material, thickness of wire, and rotation speed. A microscopic approach to the surface roughness of the flank is needed to investigate the effects of the newly proposed brush of the autonomous mobile robot on the thread holes. According to this experiment, it is reasonable to use STS brush rather than Carbon one. Optimal operating conditions are derived and the safety of APR1400 reactor stud holes maintenance can be improved.

• 한국전문물리치료학회지
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• 제26권1호
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• pp.51-59
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• 2019

Background: Chronic low back pain (CLBP) causes morphological changes in muscles, reduces muscle strength, endurance and flexibility, negatively affects lumbar stability, and limits functional activity. Plank exercise strengthens core muscles, activates abdominal muscles, and improves intra-abdominal pressure to stabilize the trunk in patients with CLBP. Objects: We investigated the effect of plank exercise on abdominal muscle thickness and disability in patients with CLBP. Methods: We classified 33 subjects into 2 groups: An experimental (n1=17) and a control group (n2=16). Patients in the experimental group participated in plank exercise and those in the control group participated in stretching exercise. Patients in both groups attended 20-minute exercise sessions thrice a week for 4 weeks. Abdominal muscle thickness in each subject was evaluated ultrasonographically, and disabilities were assessed using the Oswestry disability index (ODI). Results: Four weeks later, abdominal muscle thickness showed a significant increase over baseline values in both groups (p<.05). Patients in the experimental group reported a more significant increase in the thickness of the external oblique muscle than that in the control group (p<.05). ODI scores in the experimental group were significantly lower after intervention than before intervention (p<.05). Conclusion: Plank exercise increases the thickness of the external oblique muscle and reduces disability secondary to mild CLBP. Therefore, plank exercise is needed to improve lumbar stability and functional activity in patients with mild CLBP.

• PNF and Movement
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• 제17권2호
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• pp.293-302
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• 2019

Purpose: The purpose of this study was to investigate the effects of plank exercises involving the contraction of the adductor muscle of the hip joint on core muscle thickness and to propose an effective plank exercise method. Methods: A total of 30 healthy young adults (17 males, 13 females) voluntarily participated in the study. The subjects were randomized to the prone plank exercise with hip adductor contraction (n=10), the prone plank exercise (n=10), and the supine plank exercise (n=10) groups. Muscle thickness measurements were taken prior to starting the exercise program and after completing the program at the end of a 4-week period. The muscle thickness of the rectus abdominis (RA), multifidus (MF), external oblique (EO), internal oblique (IO), and transverse abdominis (TrA) muscles were measured using ultrasonography. Each group performed the stipulated plank exercise five times a week as follows: 5 sets of 20 seconds during the first week, 5 sets of 30 seconds in the second week, 5 sets of 40 seconds in the third week, and 5 sets of 40 seconds in the last week. Results: The three different types of plank exercises all showed significantly increased thickness of the RA, MF, EO, IO, and TrA (P<0.05). Furthermore, changes in the thickness of both the MF and TrA were statistically more significant in the groups that did the prone plank exercise with the hip adductor contraction and the supine plank exercise than in the prone plank exercise group (P<0.05). Conclusion: The study results suggest that the prone plank exercise with hip adductor contraction is a more effective method for overall activation of the RA, MF, EO, IO, and TrA than the prone plank exercise and the supine plank exercise.

• 대한통합의학회지
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• 제9권4호
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• pp.183-190
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• 2021

Purpose : The purpose of this study was to investigate the effect of side planks on the muscle thickness of the core muscles, external oblique, internal oblique, and transverse abdominis, and this study was conducted to compare whether side plank exercise according to the application of various unstable support surfaces increases the thickness by activating the action of the muscles. Methods : The subjects of this study were 30 healthy adults and were randomly and equally assigned to three groups by a random number table. All subjects were divided into three groups according to the application of an unstable support surface during the side plank(Group A = stable support, Group B = one unstable support, Group C = two unstable supports). The side plank exercise was performed 30 minutes a day, 3 times a week for a total of 4 weeks. The muscle thickness of the core muscle was measured before the intervention, 2 weeks, 4 weeks, and 3 times in total. All measured data were comparatively analyzed by repeated measures ANOVA and one-way ANOVA. The statistical significance level was set to .05. Results : The results of this study were as follows : 1. All muscles showed an interaction between training period and group. 2. There was a significant difference between the groups at the 2 weeks and 4 weeks of the internal oblique and transverse abdominis muscle measurements. Conclusion : The thickness of the abdominal muscle increased during the side plank exercise according to the support surface, and the thickness of the abdominal muscle increased the most during the side plank exercise on the unstable support surface. Therefore, it is thought that the addition of an unstable support surface will provide a more effective therapeutic effect on the thickness change of the abdominal muscle during side plank exercise.

• 대한물리의학회지
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• 제18권3호
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• pp.99-111
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• 2023

PURPOSE: This study examined the effects of pelvic compression methods on the muscle activities of the trunk muscles during plank exercises in individuals with and without low back pain. METHODS: Individuals who experienced back pain for three or more days within the last six months (low back pain group, LBPG; n = 15) and those who did not (non-experienced low back pain group, NLBPG; n = 15) were instructed to perform plank exercise without pelvic compression or while wearing a ReaLine or Com-pressor belt. The electromyography (EMG) data was measured during each session of exercise. Surface EMG signals were collected for the rectus abdominis (RA), external oblique (EO), erector spinae (ES), and gluteus maximus (GM) muscles. The data were collected during three 5-s exercises with a 1-min rest period between the three sets. RESULTS: During the plank exercise, the muscle activity of the RA in the LBPG was significantly higher than that in the NLBPG (p < .05), and greater muscle activity was observed in the LBPG even when two pelvic compression methods were applied (p < .05). The muscle activity of RA was decreased significantly during pelvic compression according to the pelvic compression methods in both groups (p < .05). No significant interaction was observed between the groups or the pelvic compression methods for the RA, EO, ES, or GM muscle activities during plank exercises. CONCLUSION: Both pelvic compression methods reduced the RA muscle activity during plank exercises in individuals who had not experienced back pain within the last six months.

• PNF and Movement
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• 제22권2호
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• pp.181-189
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• 2024

Purpose: This study aimed to identify the effect of sling-applied plank exercise on the frequency, stiffness, and decrement of the rectus abdominis and longissimus muscles of the trunk according to the stability of the base of support. Methods: Thirty-three young adults volunteered to participate and were randomly assigned to one of three groups (SS, stable support; LES, lower extremity support; and ULES, upper and lower extremity support) according to the stability of the base of support. The muscular properties of the rectus abdominis and longissimus muscles during sling-assisted plank exercise according to the stability of the base of support. were measured by using Myoton PRO (Myoton AS, Tallinn, Estonia). Statistical analysis was performed MANOVA to determine the effect of sling-assisted plank exercise on the muscular properties of the rectus abdominis and longissimus muscles according to the stability of the base of support. Post hoc analysis was conducted using Bonferroni. The level of statistical significance was set at α = 0.05. Results: When comparing the muscular properties, the muscle frequency and stiffness of the left rectus abdominis of ULES were significantly decreased compared to that of SS (p < 0.05). In the measurement time, the muscle frequency and the muscle stiffness of the right rectus abdominis increased significantly after the intervention (p < 0.05). Conclusion: It was concluded that the more unstable the base of support (ULES), the higher the exercise strength, and the muscle frequency and stiffness decreased on the rectus abdominis at rest.

• 환경위생공학
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• 제5권2호
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• pp.117-122
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• 1990

인공지인 지도지생태에 대하여 1979년 4월부터 1980년 3월까지 수온, pH, $Cl^-,\; Mg^{++}$, alkalinity, detergent, $SiO_2-Si, PO_4-P\;^{3-}, NO_3-N\;NO_2-N\;NH_4-N$, BOD, COD, DO, OM 및 OC등의 물리화학적 수질환경의 동태를 분석하고 일차생산자인 식물성플랭크톤의 다양성 및 생장과 생산성을 측정하여 생태계의 물직대사와 에너지이효율을 정량화하였다. 식물성플랭크톤의 분포는 총 28종의 우점종(Chlorophyta 11종, Bacillariophyta 9종 및 Cyanophyta 3종)이 출현하였고, chlorophyta는 전체 algal counts의 75%를 점하였다. 다양성지수는 d=0.85~2.80, $\={H}$=1.10~2.40, e=0.56~0.90였다. 현재량은 0.043~0.385g chl/$m^2$의 범위였고, 광합성율 및 호흡율의 변화는 각각 0.36~4.50와 0.10~1.40mg $O_2$/l/hr이며, 동화량은 0.6~3.8mg C/$m^2$, 태양에너지 이용효율은 연평균 2.44%였다. 인과 질소의 turnover time은 각각 20days와 3days였다.

• 한국정밀공학회지
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• 제13권11호
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• pp.25-31
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• 1996

In this paper, three different types of commercial tools -P20, NC123K and ceramic- have been used to cut austempered ductile iron(ADI). In the austempered condition the materials are hard, strong and difficult to machine. Thus, we selected a optimum tool material among three different types of used tools in machining of austempered ductile iron. It was used acoustic emission (AE) to know cutting characteristic for selected tool and investigate characteristic of AE signal according to cutting condition and relationship between AE signal and flank wear land of the ceramic tool. The obtained results are as follows ; (1) The ceramic tool among three different types of tools is the best in machining austempered ductile iron. (2) In case of ceramic tool, the amplitude level of AE signal(AErms) is mainly affected by cutting condition and it is proportional to cutting speed. (3)There have been the relationship of direct proportion between the amplitude level of AE signal and flank wear land of the tool. (4) It was observed that the value of AErms was only affected by cutting speed. Therefore it is possible to in-process detec- tion of ceraic tool's wear in case the initial value of AErms at each cutting speed decided.