• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.41-51
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• 2018

Downwash from helicopter rotor blades and external winds from various maneuvering make an unguided rocket change its trajectory and range. For the prediction of the trajectory and range, it is essential to consider the downwash effect. In this study, an algorithm was developed to calculate 6-Degree-Of-Freedom(6 DOF) forces and moments exerting on the rocket, and total flight trajectory of a 2.75-inch unguided rocket in a helicopter downwash flow field. Using Actuator Disk Model(ADM) analysis result, the algorithm could analyze the entire trajectory in various initial launch condition such as launch angle, launch velocity, and external wind. The algorithm that considered the interference between a fuselage and external winds could predict the trajectory change more precisely than inflow model analysis. Using the developed algorithm, the attitude and trajectory change mechanism by the downwash effect were investigated analyzing the effective angle of attack change and characteristics of pitching stability of the unguided rocket. Also, the trajectory and range changes were analyzed by considering the downwash effect with external winds. As a result, it was concluded that the key factors of the rocket range change were downwash area and magnitude which effect on the rocket, and the secondary factors were the dynamic pressure of the rocket and the interference between a fuselage and external winds. In tailwind case which was much influential on the range characteristics than other wind cases, the range of the rocket rose as increasing the tailwind velocity. However, there was a limit that the range of the rocket did not increase more than the specific tailwind velocity.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.1
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• pp.45-53
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• 2014

PURPOSE: In this study, we tried to find out what kind of exercise was more effective in sleep disorder by comparing melatonin in blood after applying low intensity with high intensity exercise to sleep disordered rats induced by experiment. METHODS: We used male Sprague-Dawley rats which were 8weeks old and weighted 300g. They were supplied with water and food without any restriction. We kept the room temperature at $25^{\circ}C$ and controld the length of day and night in 12 hours blocks, respectively. We divided the rats 60 into 2 groups. To one group we applied low intensity exercise, and to the other we applied high intensity exercise for 15minutes per day over a period of 4 weeks. We extracted the blood from abdominal aorta before, after exercise, moved into EDTA tube, performed centrifugation. We decanted the serum $200{\mu}l$ from the blood into microcentrifuge tube by samples and moved into polypropylene culture tubes with micro pipette. We split enzyme solution $50{\mu}l$ into the tubes with melatonin direct kits and make them react at $37^{\circ}C$ for 2 hours. We split assay buffer $50{\mu}l$ into each tube and mixed melatonin tracer $50{\mu}l$ and melatonin antiserum $50{\mu}l$, respectively. After we made them react in room temperature, we decanted the superficial layer with a centrifuge and measured the activity for 1 minute by competitive method with ${\gamma}$-counter equipment. We draw a standard curve through logit-log graph with CPM(counts per minute) and counted the melatonin by B/B0. We conducted independent t-test to examine the homogeneous of melatonin value of before low-intensity and high-intensity exercise. We performed paired t-test to compare before and after low-intensity and high-intensity exercise, respectively. We carried out independent t-test to compare melatonin value after low-intensity and high-intensity exercise. Significance level was .05. RESULTS: The results were as follows; firstly melatonin was more increased in the group who was exposed to high intensity exercise when we compared before to after high and low intensity exercise, respectively. Secondly, high intensity exercise was more effective than low intensity exercise when we compared the two. CONCLUSION: In conclusion, secretion of melatonin which is the material of sleep improvement could be promoted by high intensity exercise. Low intensity exercise acted as a stress rather than improving sleep and had a negative effect on the secretion of melatonin because the melatonin was affected by stress.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.53-57
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• 2011

The present study has been carried out to analyze the flow characteristics of a heat recovery steam generator with the change of inlet flow conditions by using numerical flow analysis. The inlet of HRSG corresponds the outlet of gas turbine exit and the flow after gas turbine has strong swirl flow and turbulence. The inlet flow condition of HRSG should be included the exit flow characteristics of gas turbine. The present numerical analysis adopted the flow analysis result of gas turbine exit flow as a inlet flow condition of HRSG analysis. The computational flow analysis result of gas turbine exit shows that the maximum axial velocity appears near circular duct wall and the maximum turbulent kinetic energy and dissipation rate exist relatively higher gradient region of axial velocity. The comparison of flow analysis will be executed with change of inlet turbulent flow condition. The first case is using the inlet turbulent properties from the result of computational analysis of gas turbine exit flow, and the second case is using the assumed turbulent intensity with the magnitude proportional to the velocity magnitude and length scale. The computational results of flow characteristics for two cases show great difference especially in the velocity field and turbulent properties. The main conclusion of the present study is that the flow inlet condition of HRSG should be included the turbulent properties for the accurate computational result of flow analysis.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.407-416
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• 2010

The purpose of this study was to examine the relationship among women's leisure dance participation, physical image and self-esteem. The subjects in this study were 300 female adults who were selected by cluster sampling from the population that consisted of women who were in their 20s to 50s. In the population, some women got leisure dance at fitness clubs, sport lovers' clubs and dance academies in Seoul and Gyeoggn Province as of 2009, and the others didn't. As for the reliability of the questionnaires used in the study, the Cronbach alpha coefficient of the questionnaires was above .70. The major statistical methods utilized in this study were Frequencies, reliability factor analysis, analysis covariate, regression analysis and path analysis. The findings of the study were as follows: First, the women who got leisuer dance evaluated their own physical image and self-esteem more favorably than the others who didn't. Second, the length of participation affected the body shape, satisfaction level and flexibility, and the intensity of participation impacted on the body shape and muscular power. Third, the length of participation had an impact on self-esteem, and the frequency of participation exerted a negative influence on that. Fourth, the degree of participation had a causal impact on physical image and self-esteem. In other words, the degree of getting leisure dance affected self-esteem in a firsthand manner and exerted a secondhand influence on that through physical image as well. The findings of the study suggested that physical image was one of major parameters to link participation in rhythmic exercise and self-esteem.

• The Journal of the Korea Contents Association
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• v.18 no.4
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• pp.586-600
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• 2018

The purpose of this study attempted to collect basic data for development of an integrated self-management program for cancer survivors who completed cancer treatment. Self-management programs are divided into symptom management and physical activity management. Symptom management includes fatigue, sleep disturbance, pain, depression and anxiety. PubMed, CINAHL and EMBASE were used for searching guidelines. Based on the guideline quality evaluation, the final 8 guidelines were analyzed. The structured table was used to extract the screening subjects, timing, contents, subjects for comprehensive assessment and contents, and summarized contents related to the physical activity and exercise in non-pharmacological approach. As a result, after the completion of cancer treatment, all cancer survivors should be screened regularly using reliable and validated tools. In the case of fatigue, physical activity was recommended as the primary intervention, but it was recommended for other symptoms as adjuvant therapy. Therefore, Cancer survivors should be encouraged to be active in their physical activity, and maintain the moderate intensity physical activity as long as they have no complication related to the cancer treatment. Motivation strategies for physical activity need to be developed and applied.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.237-243
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• 2000

Agricultural machine is currently operated by man power in the greenhouse, which is oppressively hot and humid, and is for a farmer not to work in comfortable circumstances. In the future, agricultural machine will not have to operate by man power, but it will need do by unmanned power. In order to put into the automatic and unmanned operation of agricultural machine, this system was designed and built to move through the fixed path in the greenhouse. This system was composed of guiders(wires), a limit switch, an operating equipment, its software for automatizing a machine in the greenhouse. The guider was connected between the wall pillars, and the equipment was able to slide over the fixed path made of the guider, by rectilinear and rotational motion. A micro mouse was developed with a stepping motor to calculate on the success rate of its operation with the system As might be expected, this system with the micro mouse was moved the moved the paths with a success rate of 100% on the flat plane surface in our laboratory. However, on the sand plane or the other materials plane, the success rate was not better than 80%. If the micro mouse were well operated, the success rate was would be 100%. Based on the results of this research, this system would be expected to operate well on the path made of a simple wire.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.412-419
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• 2017

Purpose:This study was conducted to identify the effects of theSemi-Fowler's position on post-operative recovery and pain for patients with laparoscopic abdominal surgery Methods: This study utilized a non-equivalent control group non-synchronized design to validate the effects of theSemi-Fowler's position. After IRB approval, 56 patients took part in this study, 29 in the experimental group and 27 in the control group. Consent was obtained from the participants. The Semi-Folwer's position was applied to experimental group and the supine position was applied to the control group for 24 hours after surgery. All data were reviewed retrospectively from April to June 2016. Collected data, frequency, percentage, average, standard deviation, chi-squared test, independent t-test and repeated measures ANOVA were conducted using SPSS 20.0. Results: There was no significant difference between the experimental and control group with regard to recovery outcomes; however, there was a significance differencebetween groups and among check times with regard to post operational pain. Conclusion:The results of this study provide information that will be usefulto the development of strategies for improving recovery outcomes and pain for laparoscopic operation patients.

• Polymer(Korea)
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• v.33 no.5
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• pp.446-451
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• 2009

Reliability evaluations of linear low density polyethylene (LLDPE) pipe with respect of thermal exposure time have been investigated in accordance with RS M 0042, which is a reliability standard for polymer pipe. As the thermal exposure time is prolonged, a progressive increase, until 250 days, in tensile strength and a slight increase in hardness are observed, while a proportional decrease in elongation at break is showed. These results can be explained by the increase of crystallinity, followed by the increase of crosslinking density, chain scission and the decrease in chain mobility, due to thermal oxidation as the exposure time increases. Long term hydrostatic pressure test result implies the existence of transition point from ductile to brittle fracture. Oxidation induction time (OIT) test is employed to monitor the thermo-oxidative degradation of LLDPE pipe. This result shows that after the exposure time is 250 days, the depletion of antioxidants added in LLDPE pipe occurs. An empirical equation as function of exposure time, under $100^{\circ}C$ thermal-degradation condition, is proposed to assess the remaining amount of antioxidants owing to thermo-oxidative degradation. Fourier transform infrared spectroscopy results show the increase of carbonyl (-C=O) and hydroxyl (O-H) function groups on the surface of thermally exposed LLDPE pipe. This result suggests that the hydrocarbon groups locally undergo the oxidation on the LLDPE surface due to thermal-degradation.

• Journal of the Korean Arthroscopy Society
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• v.4 no.1
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• pp.54-60
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• 2000

Purpose : The purpose of this study was to evaluate the gutter pathologies and the clinical results of arthroscopic treatment for ankle gutter syndrome. Materials and Methods : Seventy six patients(77 ankles) who had lesions in the ankle gutter were treated by arthroscopy. The gutter pathology could be divided into 3 categories; hypertrophic scar tissue, loose bodies and bone spurs. Fifty two patients were evaluated subjectively and functionally with authors' criteria. The follow-up period averaged 44 months(range, 2.9 year-8.5 year). Results : The incidence of the gutter lesion was $21\%$(77 ankles) among 366 ankles undergoing arthroscopy. The most common pathology was hypertrophic scar tissue. In 31 ankles$(40\%)$, the lesions were found only in gutter, and 46 ankles$(60\%)$ were associated with pathologies in other areas. All of parameters for subjective and functional evaluation were improved with statistical significance(p<0.001). Seventeen patients$(33\%)$ could returned to competitive or contact sports activity with same level of premorbid period. Conclusion : Ankle gutter is an important site of pathologies which cause chronic ankle pain, and should be explored in ankle arthroscopy. The ankle arthroscopy is a very effective treatment method fur the removal of pathologies in ankle gutter syndrome.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.49-60
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• 2017

As well as the strength check, fatigue life check is also mainly required for designing mooring lines of the floating structures. In general, forces which induce dynamic structural response significantly affect to fatigue design of the mooring lines. So, waves are mainly considered as the governing loading for fatigue design of the mooring lines. In this study, characteristics of the fatigue damage of the mooring lines for submerged floating tunnels (SFT) under irregular waves are investigated. For this study time domain hydrodynamic analysis is used to obtain motion of the tunnel and tension and stresses of the mooring lines under the specific environmental conditions. Also, the Rainflow-counting method, the Palmgren-Miner's rule, and S-N curves for floating offshore structures presented by DNV recommendation is applied to calculate the fatigue damage due to the fluctuating stresses. Referring to the design plactice of the tendon pipes for TLP (tension-leg platform), which is very similar structural system to SFT, it is assumed that a 100 year return period wave attacks the SFT systems during 48 hours and the fatigue damages due to the environmental loading are calculated. Following the analysis sequence, the effects of the tunnel draft, spacing and initial inclination angle of the mooring lines on the fatigue damage under the specific environmental loadings are investigated.