• Journal of Biomedical Engineering Research
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• v.24 no.4
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• pp.363-367
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• 2003

Contact area and pressure are important factors which directly influence a life of knee implants. Since implant's mechanical functions should be experimentally evaluated for clinical use, many studies using a knee simulator and a pressure sensor system have been conducted. However it has not been reported that the contact pressure's distribution of a knee implant motion was estimated in real-time during a gate cycle. Therefore. the objective of this study was to analyze the contact pressure distribution for the motion of a joint using the knee simulator and I-scan sensor system. For this purpose, we developed a force-controlled dynamic knee simulator to evaluate the mechanical performance of artificial knee joint. This simulator includes a function of a soft tissue and has a 4-degree-of-freedom to represent an axial compressive load and a flexion angle. As axial compressive force and a flexion angle of the femoral component can be controlled by PC program. The pressure is also measured from I-scan system and simulator to visualize the pressure distribution on the joint contact surfaces under loading condition during walking cycle. The compressive loading curve was the major cause for the contact pressure distribution and its center move in a cycle as to a flexion angie. In conclusion, this system can be used to evaluate to the geometric interaction of femoral and tibial design due to a measured mechanical function such as a contact pressure, contact area and a motion of a loading center.

• KIPS Transactions on Software and Data Engineering
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• v.1 no.2
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• pp.127-136
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• 2012

Many research of hand gesture recognition based on vision system have been conducted which enable user operate various electronic devices more easily. 3D position calculation and meaningful gesture classification from similar gestures should be executed to recognize hand gesture accurately. A simple and cost effective method of 3D position calculation and gesture spotting (a task to recognize meaningful gesture from other similar meaningless gestures) is described in this paper. 3D position is achieved by calculation of two cameras relative position through pan/tilt module and a marker regardless with the placed position. Fuzzy garbage model is proposed to provide a variable reference value to decide whether the user gesture is the command gesture or not. The reference is achieved from fuzzy command gesture model and fuzzy garbage model which returns the score that shows the degree of belonging to command gesture and garbage gesture respectively. Two-stage user adaptation is proposed that off-line (batch) adaptation for inter-personal difference and on-line (incremental) adaptation for intra-difference to enhance the performance. Experiment is conducted for 5 different users. The recognition rate of command (discriminate command gesture) is more than 95% when only one command like meaningless gesture exists and more than 85% when the command is mixed with many other similar gestures.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.67-77
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• 2008

Seismic isolation has been studied continuously as a solution of the seismic engineering to reduce the sectional forces and the damages of structures caused by earthquakes. To certify reliable design and installation of the seismic isolation systems, seismic isolation bearings should be fabricated under well planned quality control process, and proper evaluation tests for their seismic performance should be followed. In this study, shear property evaluation tests for the lead rubber bearings(LRB) and the rubber bearings(RB) were implemented and the temperature dependency tests were also implemented to evaluate the changes of shear properties according to the changes of temperature. After evaluation tests, the measured shear properties were compared to their design values and their deviation was analyzed comparing with the allowable error ranges specified in Highway Bridge Design Specifications. These results showed that a considerable number of isolation bearings have so large deviations from their design values that their error ranges were over or very close to the allowable ranges. And the test results for temperature dependency showed that the shear properties of isolation bearings would be changed in great degree by the change of temperature during their service period. If these two types of changes in their shear properties are superposed, it would possible that the changes of shear properties from their original design values are over than 50%.

• Journal of the Korean Society of School Health
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• v.9 no.1
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• pp.99-108
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• 1996

The purpose of the survey was to identify the degree and the relationship of sexual knowledge, sexual attitude and need of sex education. This information will provide useful data for a more systematic. desirable, and practical sex education. The data was collected from 300 first grade schoolchildren (150 boys and 150 girls) of two Junior high school in K city. The data was gathered by questionnaire from Nov.21 to 28, 1995. The questionnaire was modified by authors using the questionnaire developed by Lief & Reed. Data was analyzed by using the statistical computer package, SAS to manipulate the data along with percentages, means, standard deviation, t-test, $X^2$-test, GLM, and Pearson correlation coeffiency. The results in this study were summarized as follows: 1. Sexual knowledge. - The mean score of sexual knowledges showed no significant differences between boys and girls(p<0.6180), but in the areas of biological differences(boys; $11.57{\pm}2.43$, girls; $10.93{\pm}2.41$, p<0.0242), and pregnancy physiology(boys; $9.28{\pm}1.87$, girls; $10.04{\pm}2.42$, p<0.0026) showed significant difference between boys and girls. 2. Sexual attitudes. - The mean score of sexual attitudes showed no significant difference between boys and girls (p<0.8286), but in the areas of masturbation (boys : $6.69{\pm}2.22$, girls : $5.65{\pm}1.88$, p<0.0001), and premarital intercourse (boys : $5,42{\pm}1.35$, girls : $6.00{\pm}1.33$, p<0.0002) showed significant difference between boys and girls 3. Need of sex education. - The majority of the subjects wanted to learn about sexual delinquency and it's prevention(57.7%), form a friendship with the other sex(56.3%), physical differences of the other sex(52.0%), psychological differences and the charateriatics of the other sex (50.3%) and meaning of love(50.3%). 4. The relationships between sexual knowledges and sexual attitudes. - Those who had higher sexual knowledges showed more positive attitudes towards sex, and showed statistical significance(r=0.2074, p<0.0003). 5. The relationships between general charateristics and sexual knowledge. - Better students(by self-perception of school performance) had higher knowledge scores about sex. 6. The relationships between general charateristics and sexual attitudes. - Those who wanted to learn more about sex, and better students had higher attitude scores about sex. - Those who were in high standard of living had higher attitude scores about sex as well. Suggestions based on above study are as follows' 1. The planned sex education showed be performed to the schoolchildren establish responsible attitudes about sex. 2. Systematic sex education through formal school education according to age is recommended. 3. Further studies should be done to measure the effect of sex education based on the needs of the schoolchildren.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.8-15
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• 2021

This paper describes a design method using an optimization technique to satisfy the longitudinal handling quality of high maneuverable jet aircraft. The dynamic inversion technique was applied to the target aircraft, and the control gain optimization satisfied the longitudinal short-period handling quality, however, the stability margin was not considered. If the stability margin is not satisfied, it is necessary to directly readjust the gains through trial and error methods for improvement. To improve this, an additional compensator and an optimization constraint were added to the control gain optimization procedure. In addition, the degree of handling quality satisfaction with the optimization result was reevaluated, and additional control evaluation criteria for the convergence of the time response and the steady state error that the flight performance requirement set as the optimization constraint cannot be reflected, and the results are described.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.649-660
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• 2021

Through analytical method based on S-76 model, the level of rotor hub vibration reduction was analyzed according to higher harmonic actuating by individual blade control. The higher harmonic actuating method for individual blades was divided into a method of generating an additional actuating force from the pitch-link in the rotating part and generating actuating force through the active trailing edge flap control of the blade. In the 100kts forward flight conditions, the hub load analysis was performed by changing the phase angle of 15 degree for the 2P/3P/4P/5P harmonic actuation for individual blades. Through the harmonic actuation results, the sensitivity of the rotor system according to the actuating conditions was analyzed, and the T-matrix representing the characteristics of the rotor system was derived based on this analysis result. And through this T-matrix, optimal higher harmonic actuating condition was derived to minimize hub vibration level for flight condition. In addition, the effect on the performance of the rotor system and the pitch-link load under minimum hub vibration condition, as well as the noise influence through the noise analysis were confirmed.

• Review of Culture and Economy
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• v.20 no.3
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• pp.3-33
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• 2017

The present study analyzed movie consumption behavior from the perspective of transaction cost, taking into account the possible incurrence of additional costs in the process of consumers obtaining movie information to choose movies. Regression and multinomial logistic regression analyses were performed in the analysis by taking movie information and the individuals' social demographic characteristics as independent variables and the number and frequency of movies watched as dependent variables, using information from the "2015 movie consumer survey." The results showed that consumers considering elements such as "directors" and "online reviews" were found to be more active in movie consumption. The analysis of movie-watching frequency showed that the information considered when choosing a movie was different for high- and low-frequency movie viewers. Putting these factors together suggests that movie consumption can vary according to an individual's cultural capital, preferences, and their degree of movie information awareness. While existing studies have mostly analyzed the determinants of box office performance, the significance of the present study is its empirical analysis of individual movie information in terms of transaction cost. Based on the results above, it can be inferred that the cyclical structure of trading expenses influences movie consumption and, once preferences are formed through a certain level of consumption, the trading cost expenses decrease, which results in increasing consumption. Therefore, film makers need to establish and execute marketing strategies that appropriately use movie information so that consumers can reduce the trading costs necessary for movie watching.

• Composites Research
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• v.32 no.2
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• pp.96-101
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• 2019

Interfacial adhesion between fiber and resin are related to composites performance, so it is very important to evaluate them accurately. In this study, the interfacial properties of microdroplets under fatigue loading conditions were evaluated. The mechanical properties and interfacial adhesion of epoxy resin with dopamine were studied. Tensile specimens were prepared to evaluate mechanical properties and epoxy microdroplets specimens were used for the evaluation of interfacial adhesion. In addition, in the microdroplet fatigue test, the same diameter of the microdroplet was used and the experiment was performed under the same conditions. As a result, it was confirmed that mechanical and interfacial properties were improved when dopamine was applied to epoxy resin through tensile and microdroplet experiments. It is considered that dopamine improves the degree of curing of the epoxy resin and imparts hydroxyl groups to the epoxy resin to increase the mechanical properties and the interfacial adhesion between the glass fibers.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1073-1080
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• 2018

There are several types of petroleum products used for the fuel oil, according to their respective quality standards, grades and usage. Depending on the degree of oil tax rate by country, even the same petroleum products will have price gap. The illegal mixing of cheap petroleum products, which are subject to the lower tax rate, with relatively expensive transportation fuel causes problems such as tax evasion, environmental pollution and vehicle breakdown. In order to prevent illicit production and mixing of these different petroleum products, a small amount of markers are legally added to specific petroleum products. In Korea, markers are introduced and used to prevent illegal activity that kerosene used as fuel for house and commercial boiler are mixed with automotive diesel fuels, and marker contents are analyzed to use UV-Vis spectrophotometer and high performance liquid chromatography (HPLC). In this study, we have developed a method to qualitatively and quantitatively determine the marker added to petroleum products by gas chromatography-mass spectrometry (GC-MS) without adding developing reagent or sample pre-treatments.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.163-176
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• 2019

The purpose of this study is to examine the impact of PM consultant leadership competence on consulting repurchase intention and the impact of SME CEO participation on consulting repurchase intention. The validity of the measurement model was secured through CFA (Confirmative Factor Analysis) for the questionnaire data, and consistency was secured through the same method convenience, and significant results were obtained. In other words, not only the ability of PM consultant in repurchase of consulting is important, but also confirms that repurchase intention differs according to the participation of manager. Therefore, the performance that manager feels depends on the degree of manager's interest in repurchase and plays an important role in repurchase. As a result, it is important for PM to report to manager and / or make the manager participate in consulting process so that manager can be interested. In this study, it is difficult to generalize the relationship between PM's leadership role and manager's involvement in the repurchase intention. However, it is meaningful that PM's competence as well as management's participation are very important, and that this study figured out which drection PM's leadership should focus on. The purpose of this study is to investigate the effect of the variables on the repurchase intention.