• Korea Science and Art Forum
• /
• v.20
• /
• pp.421-428
• /
• 2015

Electronic/hybrid car and electroplating rectifier should have switching devices such as SCR, MOSFET, IGBT. And those switching devices should be operated by gate driver. In this paper, we propose high power gate driver that contains H-Bridge using 4 BJTs. H-Bridge and transformer generate isolate power. And gate control signal is transferred to isolated one by photo coupler and operate real switching device. We designed H-Bridge and 555-Timer by PSpice simulation and manufactured real product. Finally we succeed to operate 27V 50,000A electroplating rectifier using proposed gate driver.

• Korean Journal of Human Ecology
• /
• v.21 no.5
• /
• pp.903-913
• /
• 2012

This study investigated the effects of depression, anxiety, and impulsiveness on suicidal thoughts among adolescents with the goal of better understanding the psychological needs of adolescents and to provide them with more effective counseling and guidance. Participants for this study included 340 high school students in their first and second year living in large urban centers. Respondents answered a questionnaire that documented their experiences related to depression, anxiety, impulsiveness, and suicidal thoughts. Data analysis was performed using the means, standard deviations, correlation analysis, and multiple regression using the IBM SPSS 19.0 statistics program. The results were as follows. There was no statistically significant difference in anxiety and impulsiveness based on gender. However, female respondents demonstrated a higher rate of suicidal thoughts than male respondents. Second, in both sexes, comparative analysis between depression, anxiety, impulsiveness, and suicidal thoughts revealed that respondents with higher levels of depression and anxiety demonstrated elevated levels of suicidal thoughts. Impulsiveness demonstrated a correlation with suicidal thoughts only for female participants. Third, while depression and anxiety affected suicidal thoughts in both male and female respondents, impulsiveness did not affect suicidal thoughts, with depression having the strongest effect.

• Advances in aircraft and spacecraft science
• /
• v.9 no.2
• /
• pp.119-130
• /
• 2022

Supersonic projectiles like rockets, missiles, or aircraft find various applications in the field of defense. The shape of the wings is mainly designed as wedge shape or delta wings for supersonic vehicles. The study of supersonic flows over the wedges and flat plate delta wings around the large scale of incidence angle is considered in the supersonic projectile. In the present paper, the prime attention is to study the pressure at the nose of the plane wedge over the various Mach number and the various angles of incidence. Ghosh piston theory is used to obtain the pressure distribution analytically, and the results are compared with CFD analysis results. The wedge angle and Mach number are the parameters considered for the research work. The range of wedge angle is 50 to 250, and Mach number is 1.5 to 4.0 are considered for the current research work. The analytical results show excellent agreement with the CFD results. The results show that both the parameters wedge angle and Mach number are influential parameters to vary the static pressure. The static pressure increases with an increase in Mach number and wedge angle.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.26 no.6
• /
• pp.86-100
• /
• 2022

In this paper, the concept and characteristics of the nuclear propulsion system were introduced and the state of the art for the nuclear-powered space propulsion in abroad were summarized. Since uranium used in nuclear propulsion has a very high energy density per unit mass, it has exceptional specific impulse performance compared to the existing chemical propulsion method and can reduce the amount of fuel loaded, thereby having advantage for long-distance exploration. For this reason, advanced countries in space development are recently spurring to the research of nuclear propulsion technology, and it is judged that the development of a propulsion engine using nuclear power is absolutely necessary in order to gain an competitive edge on the space development.

• East Asian mathematical journal
• /
• v.39 no.4
• /
• pp.419-436
• /
• 2023

In this study, we aimed to develop a teacher-adaptive platform model that enhances teachers' instructional activities and teaching capabilities, allowing them to conduct intended lessons effectively. The platform is designed to support various teaching and learning activities based on the instructional situation, and additionally provides teaching and learning materials, assessment questions, and results. The developed teaching and learning platform utilized Moodle, an open-source-based LMS solution that provides various tools for online learning. The platform was specifically designed for teaching conic sections in high school geometry, and it was constructed to enable teachers to deliver their intended lessons effectively.

• The Korean Journal of Health Service Management
• /
• v.7 no.2
• /
• pp.161-177
• /
• 2013

This study aims to provide basic evidence for establishing prevention programs of school' mental health by identifying the factors of middle and high school student's depression and suicidal ideation related to stress of peer-relationship. For this purpose, we analyzed the data of 6,924 (who Experienced stress related to peer-relationship) among the 2012 Korean Youth Health Risk Behavior Online Survey(8th). In demographic characteristics, subjective academic achievement affects depression in the case of girls. In health-related characteristics, medical treatment by violence, drinking experience, smoking experience have an effect on depression in the case of boys. Subjective health, drinking experience, smoking experience, drug experience are the factors affecting suicidal ideation both boys and girls. In order to promote mental health of youth, school-based prevention education complementing existing realistic problems needs to be implemented.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.4
• /
• pp.1866-1883
• /
• 2019

As the youngest branch of information hiding, network covert timing channels conceal the existence of secret messages by manipulating the timing information of the overt traffic. The popular model-based framework for constructing covert timing channels always utilizes cumulative distribution function (CDF) of the inter-packet delays (IPDs) to modulate secret messages, whereas discards high-order statistics of the IPDs completely. The consequence is the vulnerability to high-order statistical tests, e.g., entropy test. In this study, a rich security model of covert timing channels is established based on IPD chains, which can be used to measure the distortion of multi-order timing statistics of a covert timing channel. To achieve rich security, we propose two types of covert timing channels based on nested lattices. The CDF of the IPDs is used to construct dot-lattice and interval-lattice for quantization, which can ensure the cell density of the lattice consistent with the joint distribution of the IPDs. Furthermore, compensative quantization and guard band strategy are employed to eliminate the regularity and enhance the robustness, respectively. Experimental results on real traffic show that the proposed schemes are rich-secure, and robust to channel interference, whereas some state-of-the-art covert timing channels cannot evade detection under the rich security model.

• Proceedings of the Korea Technology Innovation Society Conference
• /
• 2012.11a
• /
• pp.216-219
• /
• 2012

Spending on research and creative wrtings in South Korea been growing. In this study, we introduce the legal analysis for IPR like copyrights. Current copyright law(Art. 23, Sec.1) allows to open some writings previously published in the textbooks under high school. Can this custom be justified? There is conflicts between right of education and intellectual property. We review preliminary issues before concentrated research.

• Journal of Digital Convergence
• /
• v.15 no.8
• /
• pp.417-422
• /
• 2017

This study conducted frequency analysis for male and female patients aged 60 and over from the results of analyzing improvement strategies for inconvenience due to wearing alopecia wigs. When the patoent started perceive their depilatory diseases was right after treatment of anticancer drugs or radiotherapy, and they were found to suffer from inconveniences of being dried, etc. After treatment of chemotherapy, as for the falling-out parts, eyebrows were found to be the highest 52.1%, and pubic hair 38%, axilla hair 29% in that order. And the inconvenience level of wearing wigs among the patients with the different background of education indicates that the professions of the patients affect the ease of use. It is presumed that the easiness in use which the college graduates, high school graduates, and postgraduates showed is attributable to the age difference. to improve the inconveniences from cancer patients wearing wigs, scape troubles and close adhesion are constantly needed.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.2
• /
• pp.547-565
• /
• 2012

The design, development and deployment of Mobile Agent (MA) systems for high-level inference and surveillance in wireless sensor networks and RFID systems have drawn increasing attention in the past decade. To answer how the state-of-the-art of MA in a wide range of ubiquitous and sensor environments is, this paper investigates the current progress of MA. It proposes a taxonomy, by which MA systems in ubiquitous computing environments are decomposed and discussed. Then, this paper provides insights into the strengths and weaknesses of existing efforts. Finally, it presents a series of solutions from the viewpoint of various roles of MA in ubiquitous environments and situations.