• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.25-37
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• 2005

For pump-fed rocket propulsion system, the temperature of LOX to be supplied to turbopump inlet should be satisfied with pump inlet temperature requirement during all operating stages, as excessive temperatures can result in cavitation due to reduction in NPSH, thus either damaging the pump or adversely affecting pump performance rise. So exact estimation of LOX temperature rise is absolutely needed for developing reliable propulsion system. This paper presents systematic analysis scheme for estimating inner process of cryogenic propellant tank which is needed for LOX temperature rise. And this paper presents LOX temperature rise and thermal stratification for all rocket operating stages including cooling, filling, waiting, pre-pressurization and firing, with the application of buoyancy driven boundary layer theory.

• Spatial Information Research
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• v.16 no.3
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• pp.317-330
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• 2008

In this paper, the acquisition of digital imagery and the orthoimage generation were performed to set up working process. And another purpose of this thesis is to evaluate the accuracy of orthoimage by overlapping digital topographic map and digital cadastral map on it. The digital topographic map and digital cadastral map were superimposed on the orthoimage to check the accuracy as another approach of evaluation. The RMSE is ${\pm}0.364m$ in X direction and ${\pm}0.413m$ in Y direction with digital topographical maps(1/5,000). And the RMSE is ${\pm}1.283m$ in X direction and ${\pm}1.085m$ in Y direction with digital cadastral map. It is necessary for the application of a newly developed digital aerial camera to make an exact synchronization between GPS/IMU data and image data, use a technology for setting a standard image resolution and the number of ground control points.

• Journal of Service Research and Studies
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• v.6 no.4
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• pp.47-57
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• 2016

Open source has an amazing spread with the advent of smartphones. Open-source Moodle in e-learning areas are free of LMS (Learning Management System) and the most widely used worldwide, except for the black board commercial programs. One reason is well designed to support collaborative learning and interaction based on constructivist principles, which is the core principle of e-learning in particular that the theoretical basis of educational technology has a high educational effectiveness and benefits. This study examines the operational practices of collaborative learning using open source learning management system Moodle program. It introduces specific information to support the user of the collaborative learning. It looks at the advantages and singularity of collaborative learning in e-learning through examples shown. The purpose of this study is the importance of the relationship between learners and the importance of self-learning of collaborative learning through collaborative learning in a knowledge repository of Moodle. In addition, collaborative learning outcomes are is based on the motivation of learners and playfulness.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.2
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• pp.128-133
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• 2015

This paper describes the construction of a static 3D ultrasonography image by tracking the radiation beam position during the handy operation of a 1D array probe to enable point-of-care use. The theoretical model of the transformation from the translational and rotational information of the sensor mounted on the probe to the reference Cartesian coordinate system was given. The signal amplification and serial communication interface module was made using a commercially available sensor. A test phantom was also made using silicone putty in a donut shape. During the movement of the hand-held probe, B-mode movie and sensor signals were recorded. B-mode images were periodically selected from the movie, and the gray levels of the pixels for each image were converted to the gray levels of 3D voxels. 3D and 2D images of arbitrary cross-section of the B-mode type were also constructed from the voxel data, and agreed well with the shape of the test phantom.

• Korean journal of food and cookery science
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• v.32 no.1
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• pp.136-146
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• 2016

The purpose of this study was to investigate whether there was a gender difference in motivating university students to decrease their sodium intake and to identify effective motivating factors. Within the protection motivation theory (PMT) framework, a survey questionnaire was developed to measure participants' perceptions on the severity of and the vulnerability to risk of serious diseases due to the high sodium intake, as well as the effectiveness (response efficacy) and the ability to perform preventive measures (self-efficacy). Behavioral intentions on five specific practices (checking nutrition label, consuming more fruits and vegetables, consuming less soups, avoiding spicy and pungent food, purchasing less instant or restaurant foods) related to decreasing sodium intake were also included. A total of 294 usable response data were collected from university students (92 male, 202 female) in Busan and Gyeongnam in June 2015 and analyzed using IBM SPSS 22. Severity was the highest (4.04) PMT factor followed by response efficacy (3.72), self-efficacy (3.42), and vulnerability (3.26). Compared to male students, female students thought that the threat was more severe (t=6.035, p<0.001) and reducing sodium intake would be effective to prevent serious illnesses (t=4.724, p<0.001), but their vulnerability and self-efficacy perceptions were not different from male students. Among the five items measuring behavioral intention, female students were more likely to increase fruits and vegetables consumption (t=3.811, p<0.001), while male students were more likely to avoid spicy and pungent foods (t=2.336, p=0.020). Based on findings of this study, the recommended strategy to effectively motivate university students to lower their sodium consumption level is the development of campaign focused on increased vulnerability perception, response efficacy, and ease of practicing preventive measures instead of emphasizing the severity of the consequences.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.101-106
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• 2011

In this paper, our goal is to design the controller which operates a manufacturing system, discrete event system, guaranteeing user specification. In specially, based on supervisory control theory W. M. Wonham, our work consists in performing the controller using Petri nets possible parallelism. In addition, we consider the problem of allocation for resources sharing of the issues to consider when designing using Petri net. The controller can be generated by synthesis of user specification model and plant model after giving the management for the resource sharing. This created controller can control the deadlock and starvation which can occur in the case with resource sharing. Previous studies proposed the Constrained Synchronous Reachability graph to synthesis of the two Petri nets models. Therefore, we provide the controlled system which forbids a deadlock and starvation using the result of previous studies.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.66-74
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• 2005

This paper presents an implementation of digital servo speed control system of SPMSM(Surface-mounted Permanent Magnet Synchronous Motor) for industrial application with Direct Torque Control(DTC) using TMS320F2812 DSP. Although, the vector control scheme is adapted in many industrial servo system, but the DSP calculation ratio is increased by reference frame transformation and SVPWM of vector control. Therefore, this paper investigate the possibility of DTC scheme for industrial servo drive system instead of vector control scheme. DSP calculation ratio is compared between vector control and DTC algorithm in addition to the characteristic of speed control response. The suggested SPMSM control system shows the possibility of DTC scheme for industrial servo motor drive system instead of a vector control algorithm.

• Journal of Korea Game Society
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• v.18 no.4
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• pp.53-64
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• 2018

The digital era opens with the changing times and many parts of life has become convenient. With this convenience of living, the obesity rate of people is gradually increasing, and the necessity of exercise is emerging. However, many studies have shown that many people do not exercise or stop exercising in three to six months. In this paper, we have designed and developed a "Walking Pet" prototype, a healthcare-inspired AR game, based on the theoretical background of exercise and the precedent studies to verify these facts. The developed "Walking Pet" provides exercise data to motivate the person to exercise and apply the pet system to eventually enjoy the exercise. In order to verify the effectiveness of the "Walking Pet" prototype developed in this paper, we surveyed 100 males and females in need of health care applications and surveyed the satisfaction of pure functional aspects.

• Journal of Music and Human Behavior
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• v.14 no.2
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• pp.91-105
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• 2017

Community music therapy (CoMT) has been recently developed and expands the opportunities for music therapy. The concept of CoMT is introduced in this article, and its three attributes of community, music, and health are reviewed. This study specified each attribute of CoMT: a community (a group of people, a field where members of a group interact with each other), music (a substance of interaction, collective music-making), and health (motivation and goal of interaction, relational and social well-being). The application and interactions of the three attributes of CoMT are introduced as in the concept of community music, music and health, and community health. How CoMT can be applied to the field of music therapy is also detailed and based on the concept of CoMT and its relationship with the attributes, the CoMT was reconstructed as CoMuHeal in this study. Future studies are needed to propose how music therapy approaches can be developed to provide music for well-being and better health in the community and how CoMT can be applied in collaboration with other professional fields.

• The Journal of the Korea Contents Association
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• v.16 no.4
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• pp.455-465
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• 2016

The purpose of this study was to examine the effect of twitter influenctials on users' willingness on express opinions. Based on the spiral of silence and corrective action hypothesis, the contradictory hypotheses were drawn. The online expeiment was conducted to verify which hypothesis is valid. Participant were assigned to the four experimenatal conditons: a famous influential's twit which agrees with the issue; a famous influential's twit which disagrees with the issue; an ordinary influential's twit to agree with the issue; an ordinary influential's twit to disagree with the issue. Results showed that opinion congruency with a twitter influential did not influence participants' willingness to express opinion online and offline, but the interaction effect with the type of influentials was found. Opinion dissonance with an ordinary tiwtterian increased willingness to express opinion. The findings suggest that twitter influentials, particulary an ordinary influentials with differnet opinions, can motivate users to express their own opinion.