• The Journal of Information Systems
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• v.28 no.3
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• pp.249-276
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• 2019

Purpose The purpose of this study is to develop a prediction model and decision rules for the elderly's suicidal ideation based on the Korean Welfare Panel survey data. By utilizing this data, we obtained many decision rules to predict the elderly's suicide ideation. Design/methodology/approach This study used classification analysis to derive decision rules to predict on the basis of decision tree technique. Weka 3.8 is used as the data mining tool in this study. The decision tree algorithm uses J48, also known as C4.5. In addition, 66.6% of the total data was divided into learning data and verification data. We considered all possible variables based on previous studies in predicting suicidal ideation of the elderly. Finally, 99 variables including the target variable were used. Classification analysis was performed by introducing sampling technique through backward elimination and data balancing. Findings As a result, there were significant differences between the data sets. The selected data sets have different, various decision tree and several rules. Based on the decision tree method, we derived the rules for suicide prevention. The decision tree derives not only the rules for the suicidal ideation of the depressed group, but also the rules for the suicidal ideation of the non-depressed group. In addition, in developing the predictive model, the problem of over-fitting due to the data imbalance phenomenon was directly identified through the application of data balancing. We could conclude that it is necessary to balance the data on the target variables in order to perform the correct classification analysis without over-fitting. In addition, although data balancing is applied, it is shown that performance is not inferior in prediction rate when compared with a biased prediction model.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.2
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• pp.49-57
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• 2019

Purpose: This study aimed to investigate the application of temperature to balance the training by observing the effect of sensory changes in the foot sole area on dynamic equilibrium ability through change in the sole temperature. Methods: Participants (n=49), who were selected as a certain standard, applied cold and hot packs for ten minutes at two-week intervals, and the laboratory's internal temperature was maintained at $25^{\circ}C$. The subjects were measured before and after the cold and hot applications in the stable condition with bare feet. Before each experiment applied the cold and hot packs, the balance ability of the ordinary temperature was measured once by conducting a limit of stability test using Biorescue, and the changes in balance ability were observed by measuring once after applying the temperature to the foot sole by means of the ice pack and the hot pack. Results: The results of the dynamic balance test, both before and after the temperature application, were compared, and it was confirmed that the moving area before and after cold application decreased significantly, and the moving area before and after application was not significantly different. The mean of pre-post area differences was found to have decreased at a statistically significant rate in the forward, backward, rightward, leftward, and total areas for the group that received the cold application compared to the group that received the hot application. Conclusion: These findings showed that cold application to the foot sole decreased dynamic balance. There was no significant difference in the dynamic balance ability both before and after the hot application to the foot sole, so it is difficult to conclude that the hot application affected dynamic balance.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.60-67
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• 2019

To understand the low frequency instability(LFI) characteristics in hybrid rockets combustion, effects of equivalence ratio variations on the phase shift between pressure and heat release oscillations were investigated by using the direct numerical simulation. The change in the equivalence ratio of the main chamber was simulated by the temperature and composition variation of the combustion gas introduced into the post-combustion chamber. In the results, additional combustion appeared along with vortex generation at the backward step, and combustion pressure and heat release oscillations were observed as the vortex moved. In addition, the results confirmed that the phase difference between the pressure and heat release oscillation shifts because of the changes in the propagation velocity of pressure wave as the temperature of combustion gas changes.

• Physical Therapy Korea
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• v.26 no.2
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• pp.1-7
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• 2019

Background: In previous studies, changes in postural alignment were found when the slope was changed during walking. Downhill walking straightens the trunk by shifting the line of gravity backward. Objects: This study investigated the effect of the downhill treadmill walking exercise (DTWE) on thoracic angle and thoracic erector spinae (TES) activation in subjects with thoracic kyphosis. Methods: A total of 20 subjects with thoracic kyphosis were recruited for this study. All the subjects performed the DTWE for 30 minutes. A surface EMG and 3D motion capture system were used to measure TES activation and thoracic angle before and after the DTWE. Paired t-tests were used to confirm the effect of the DTWE (p<.05). Results: Both the thoracic angle and TES activation had significantly increased after the DTWE compared to the baseline (p<.05). An increase in the thoracic angle indicates a decrease in kyphosis. Conclusion: The DTWE is effective for thoracic kyphosis patients as it decreases their kyphotic posture and increases the TES activation. Future longitudinal studies are required to investigate the long-term effects of the DTWE.

• PNF and Movement
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• v.17 no.1
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• pp.93-101
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• 2019

Purpose: This study aimed to investigate lower extremity muscle activation to the variable weight shift on the affected side of patients with hemiplegia. Methods: Eighteen patients with chronic hemiplegia volunteered to participate in this study. All participants performed three types of weight shift (sideways, forward, and backward) in limits of stability on the affected side. Muscle activation in a paralyzed leg was measured with electromyography on the gluteus medius, tensor fasciae latae, rectus femoris, and biceps femoris; furthermore, the attached area was recommended by SENIAM projects. Each weight shift was performed three times, and then the mean value of the three measurements was analyzed. The data were analyzed by measuring the symmetrically standing position with the reference voluntary contraction (RVC) and was standardized with the percentage of RVC method. Results: No significant difference in lower extremity muscle activation occurred according to the three types of variable weight shift. However, significant differences in lower extremity muscle activation did occur with each weight shift position. In addition, activation increased at the rectus femoris and decreased at the gluteus medius and tensor fasciae latae. Conclusion: Hip abductor muscle strength training and variable weight shifts on the affected side must increase to improve patients'balance and limits of stability.

• The Korean journal of sports medicine
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• v.36 no.4
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• pp.197-206
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• 2018

Purpose: This study analyzed the muscle activity changes induced by motions of reaching forward and chest expansion that were examined from the bilateral muscles with rectus abdominis, external oblique, multifidus, and longissimus thoracic using Pilates cadillac instrument. Methods: Nine young adult women, who have no musculoskeletal disorder and any of chronic diseases, were participated. Surface electromyography system was used for recording of all signals produced by muscles, and then normalized as percentage of maximum voluntary isometric contraction (%MVIC). The paired t-test and repeated measures of analysis of variance was performed. Results: Reaching-forward motion showed a higher muscle activity from non-dominant external oblique muscle than that of the chest-expansion motion. During both reaching-forward motion and chest-expansion motion, MVIC values collected from dominant side of external oblique muscle were shown a significantly lower than the values obtained from non-dominant side (p<0.05). Conversely, %MVIC values in external oblique muscle collected from dominant side showed a significantly higher than the values obtained from non-dominant side of the same oblique muscle (p<0.05). Reaching-forward motion was caused a higher %MVIC on non-dominant external oblique muscle than that of the chest-expansion motion (p<0.05). Regardless of dominant or non-dominant sides, external oblique muscle was shown the highest activation rate of all the other muscles during reaching forward action, and longissimus thoracic muscle was shown the highest activation rate of all the other muscles during chest expansion action. Conclusion: Reaching-forward motion is suitable for activating an external oblique muscle, and chest-expansion motion is an effective enough in activating of longissimus thoracic muscle.

• Korean Journal of Agricultural Science
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• v.48 no.3
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• pp.597-606
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• 2021

Due to the characteristics of the farmland in Korea, forward and reverse shift is the most used. The fatigue of farmers is caused by forward and reverse shifting with a manual transmission. Therefore, it is necessary to improve the convenience of forward and backward shifting. This study was a basic study on the development of a current control system for forward and reverse shifting of agricultural tractors using proportional control valves and a controller. A test bench was fabricated to evaluate the current control accuracy of the control system, and the stability of the controller was evaluated through CPU (central processing unit) load measurements. A controller was selected to evaluate the stability of the proportional valve controller. The stability evaluation was performed by comparing and analyzing the command current of the controller and the actual current measured. The command current was measured using a CAN (controller area network) communication device and DAQ (data acquisition). The actual current was measured with a current probe and an oscilloscope. The control system and stability evaluation was performed by measuring the CPU load on the controller during control operations. The average load factor was 12.27%, and when 5 tasks were applied, it was shown to be 70.65%. This figure was lower than the CPU limit of 74.34%, when 5 tasks were applied and was judged to be a stable system.

• The Research Journal of the Costume Culture
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• v.29 no.4
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• pp.471-487
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• 2021

The purpose of this study was to analyze changes to body measurements and silhouettes after wearing an early 19th century women's corset. Two types of corsets were tested. Changes in body size and silhouette were compared based on the levels of tightening strength of the corset. The tightening strength was adjusted in 4 steps by making the length of back fastening string 10-40 cm shorter than the standard. The silhouette was compared with the front silhouette and the side silhouette. The results were as follows. After wearing the experimental 19th century corsets, the chest circumference and front interscye length increased. However, the chest circumference did not increase proportionally to the tightening strength. The underbust circumference, waist circumference, and back interscye length also decreased. The waist width was decreased to create a slim front silhouette. The change in the body silhouette differed depending on the style of the experimental corset. The experimental corset made with the six-piece torso pattern changed the posture so that the shoulders were pulled back and the chest was pushed forward. The experimental corset with the side bodice pattern resulted in the subject's shoulders reclining backward and the chest and abdomen extending forward. The results of this study show that women's body sizes and silhouettes could be changed by wearing the early 19th century corsets, but the changes in body size and silhouette vary depending on the wearer's individual body type or corset style.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.10a
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• pp.74-74
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• 2017

Electrorefining is a key step in pyroprocessing. The electrorefining process is generally composed of two recovery steps - the deposit of uranium onto a solid cathode and the recovery of the remaining uranium and TRU elements simultaneously by a liquid cadmium cathode. Uranium deposit recovered from the solid cathode is a dendritic powder. It is necessary to separate the adhered salt from the deposits prior to the consolidation of uranium deposit. The adhered salt is composed of lithium, potassium, uranium, and rare earth chlorides. Distillation process was employed for the cathode processing. One of the operation methods is distillation of the salt at low temperature ($900^{\circ}C$), and then melting of the deposit at high temperature to avoid a backward reaction. For the development of the salt distiller, the distillation behavior of the low vapor pressure chlorides should be studied. Rare earth chlorides in the adhered salt of uranium deposits have relatively low vapor pressures compared to the process salt (LiCl-KCl). In this study, the evaporation rates of the lanthanum and neodymium chlorides were measured for the salt separation from electrorefiner uranium deposits in the temperature range of $825{\sim}910^{\circ}C$. The evaporation rate of both chlorides increased with an increasing templerature. The evaporation rate of lanthanum chloride varied from 0.12 to $1.68g/cm^2/h$. Neodymium chloride was more volatile than lanthanum chloride. The evaporation rate of neodymium chloride varied from 0.20 to $4.55g/cm^2/h$. The evaporation rate of both chlorides are more than $1g/cm^2/h$ at $900^{\circ}C$. Even though the evaporation rates of both chlorides were less than that of the process salt, the contents of the lanthanide chlorides were small in the adhered salt. Therefore it can be concluded that $900^{\circ}C$ is suitable for the operation temperature of the salt distiller.

• Journal of Engineering Education Research
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• v.24 no.1
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• pp.3-14
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• 2021

The purpose of this study is to analyze the characteristics of efficient problem-solving teams and inefficient problem-solving teams using SYMLOG. In this study, 35 college students majoring in engineering education at C university were organized into 7 teams and carried out technological problem solving projects over one semester. Based on the results of the team project, the top 2 teams were defined as efficient problem solving teams and the bottom 2 teams were defined as inefficient problem solving team, and analyzed the characteristics of the team using SYMLOG. The main results are as follows: First, an analysis of SYMLOG from efficient problem solving teams and inefficient problem solving teams showed that there was a difference between self-awareness and others' perception in terms of U(Upward)-D(Downward) dimension. Second, in the inefficient problem solving teams, there was a significant difference between self-awareness and others' in the F(Forward)-B(Backward) dimension. Third, there was no difference between self-awareness and others' in both efficient and inefficient teams at the P (Positive)-N(Negative) dimension. Fourth, an efficient problem-solving team had a clear leader, and there was a team member who supported the leader. On the other hand, the inefficient problem-solving team did not have a clear leader, or one person played the role of leader and there were no team members supporting the leader.