• Journal of Biosystems Engineering
• /
• v.43 no.2
• /
• pp.94-102
• /
• 2018

Purpose: In this study, a maintenance free super-capacitor battery charging system based on the photovoltaic module, to be used in agricultural electric carriers, was developed and its charging characteristics were studied in detail. Methods: At first, the electric carrier system configuration is introduced and the electric control components are presented. The super-capacitor batteries and photovoltaic module used in the experiment are specified. Next, the developed charging system consisting of a constant current / constant voltage Buck converter as the charging device and a super-capacitor cell as a balancing device are initiated. The proposed circuit design, a developed PCB layout of each device and a proportional control to check the current and voltage during the charging process are outlined. An experiment was carried out using a developed prototype to clarify the effectiveness of the proposed system. A power analyzer was used to measure the current and voltage during charging to evaluate the efficiency of the energy storage device. Finally, the conclusions of this research are presented. Results: The experimental results show that the proposed system successfully controls the charging current and balances the battery voltage. The maximum voltage of the super-capacitor battery obtained by using the proposed battery charger is 16.2 V, and the maximum charging current is 20 A. It was found that the charging time was less than an hour through the duty ratio of 95% or more. Conclusions: The developed battery charging system was successfully implemented on the agricultural electric carriers.

• The Journal of the Korea Contents Association
• /
• v.11 no.12
• /
• pp.294-306
• /
• 2011

The purpose of this research is to provide a primary data to help adaptation of active duty soldiers' military life by figuring how self-esteem, anxiety of interpersonal relationships, and depression are related to adaptation directly or indirectly. The research has done by 127 of the soldiers on service. According to the result of this research, when their self-esteem gets raised, the anxiety of interpersonal relationship and the rate of depression go down. This higher self-esteem effects on getting higher adaptation of military life. However, if the anxiety of interpersonal relationships grows, this causes much more serious depression and makes hard to get adaptation of military life. Consequently this research identifies that anxiety of interpersonal relationships as a parameter mediates between self-esteem and adaptation of military life. In order to help soldiers adapt to their military life properly, the discussion and proposal have done with direct or indirect relationship among variables.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.2
• /
• pp.271-279
• /
• 2008

In this paper, we investigate interference between short-range radiocommunication devices(SRDs) with frequency hopping spread spectrum(FHSS) and direct sequence spread spectrum(DSSS) methods when they are in the same frequency bands. In order to analyze interference from unwanted emission of SRD with DSSS to that of FHSS, Monte-carlo(MC) simulation method is employed and interference probabilities are calculated. We simulate interference scenarios in accordance with several duty cycles and bandwidths. It is also assumed that the propagation model is free space. The effect of distance between interfering transmitter and victim receiver is analyzed and bit error rate(BER) is simulated. From the interference analysis results, it is shown that duty cycle affects compatibility more than band-width does. Also, we can make sure of the separation distance which satisfies BER criterion when there are only one interfering transmitter and multiple interfering transmitters.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.2
• /
• pp.61-68
• /
• 2014

Function of battery bank stores energy for DC load in general, and DC power system of the nuclear power plant is used to supply DC loads for safety- featured instrumentation and control such as inverter, class 1E power system control and indication, and station annunciation. Class 1E DC power system must provide a power for the design basis accident conditions, and adequate capacity must be available during loss of AC power and subsequent safe shutdown of the plant. In present, batteries of Class 1E DC power system of the nuclear power plant uses lead-acid batteries. Class 1E batteries of nuclear power plants in Korea are summarized in terms of specification, such as capacity, discharge rate, bank configuration and discharge end voltage, etc. This paper summarizes standards of determining battery size for the nuclear power plant, and analyzes duty cycle for the class 1E DC power system of nuclear power plant. Then, battery cell size is calculated as 2613Ah according to the standard. In addition, this paper analyzes performance test results during past 13 years and shows performance degradation in the battery bank. Performance tests in 2001 and 2005 represent that entire battery cells do not reach the discharge-end voltage. Howeyer, the discharge-end voltage is reached in 14.7% of channel A (17 EA), 13.8% of channel B (16 EA), 5.2% of channel C (6 EA) and 16.4% of channel D (19 EA) at 2011 performance test. Based on the performance test results analysis and size calculation, battery capacity and degradation by age in Korearn nuclear power plant is discussed and would be used for new design.

• Korean Journal of Community Nutrition
• /
• v.10 no.4
• /
• pp.546-554
• /
• 2005

The purpose of this study was to identify the relationship between the levels of foodservice management activities and job satisfaction of the dietitians in elementary schools. Out of 130 questionnaires distributed to elementary school dietitians in Incheon, 127 were returned and analyzed ($98\%$ response rate). The questionnaire included two multiple-item scales for measuring foodservice management activities and job satisfaction, respectively. All the items in the scales were coded 1 to 5 for 'certainly no', 'no', 'neutral', 'yes', and 'certainly yes' and grouped by using factor analyses. Most of the responding dietitians were working for schools in urban areas and have independently managed on-site kitchens. The 19 items on food service management activities were grouped into 6 factors and the mean scores of the levels of Personnel Hygiene Management, Education & Training, Sanitation & Safety Management, Menu Quality Management, Service Management, and Environment Management were 4.76, 4.26, 4.24,4. 05, 3.61 and 3.39, respectively. The 23 items on job satisfaction were grouped into 4 factors and the mean scores of the satisfaction levels of Systematic Environment, Job Duty, Job Condition, and Physical Environment were 3.38, 2.83, 2.53, and 2.08, respectively. Overall, the levels of food service management activities and job satisfaction were positively associated with a correlation coefficient of 0.254 (p > 0.01). In particular, satisfaction levels on job duty itself and systematic environment were positively associated with the levels of overall management activities. The results suggest that improving dietitians' job satisfaction could increase the levels of management activities of school foodservice dietitians, resulting in quality improvement of school food service.

• Convergence Security Journal
• /
• v.13 no.2
• /
• pp.195-202
• /
• 2013

Defense reform our military for the globalization of information. Scientific command structure, troop structure, unit structure, step-by-step into the power structure while promoting a history of quantitative-oriented structure, and structure of the quality of state-of-the-art technology-driven transition in the middle of the bottle numberplans about the current 3.3-fold increase in reducing the cadre(officers and NCOs). NCO groups in the executive, especially expanding the current level of 100% increase in the rate of long-serving, while ensuring a stable job and to superior resources to secure a stable policy through science. Military alliance is now underway. In the midst of this group, and urged the group at the University of the leading military and specialized resources to ensure each agreement required by subjects to reflect. Thus effectively improve the quality of education and the demands of the job analysis, DACUM curriculum development methods and procedures can be applied at the time of urgent need for foster an excellent resource for the discharge of curriculum development at the University of Selected as a core job, career, and job classification configuration inside of Duty according to KST derived from the group reflect on the training courses to meet the requirements in the curriculum through the development of curriculum, job definition, job model set to propose.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.3
• /
• pp.239-246
• /
• 2014

In the context of wireless sensor networks, one of major issues is energy conservation. For low power communication, by utilizing our experimental results for the relation between clock drift and synchronization interval, we designed a new protocol which can support a wide range of duty cycles for applications with very low traffic rate and insensitive delay. The transmission (TX) node in the protocol synchronizes with the reception (RX) node very before transmitting a packet, and it can adaptively estimate the synchronization error size according to the synchronization interval from minutes to hours. We conducted simulations and a testbed implementation to show the efficacy of the proposed protocol. We found that our protocol substantially outperforms other state-of-the-art protocols, resulting in order-of-magnitude increase in network lifetime over a variety of duty cycles.

• Journal of Magnetics
• /
• v.15 no.4
• /
• pp.213-220
• /
• 2010

Since the hypothalamus immediately reacts to a nerve by processing all the information from the human body and the external stimulus being conducted, it performs a significant role in internal secretion; thus, a diverse and rapid stimulus pulse is required. By detecting Zero Detector accurately via the application of AVR on-Chip (ATMEL) using commercial electricity, chopping generates a stimulus pulse to the brain using an IGBT gate to designate a new magnetic stimulation following treatment and diagnosis. To simplify and generate a diverse range of stimuli for the brain, chopping can be used as a free magnetic stimulator. Then, commercial frequency (60Hz) is chopped precisely at the first level of the leakage transformer to deliver an appropriate stimulus pulse towards the hypothalamus when necessary. Discharge becomes stable, and the chopping frequency and duty-ratio provide variety after authorizing a high-pressure chopping voltage at the second level of the magnetic stimulator. These methods have several aims. The first is to apply a variable stimulus pulse via accurate switching frequency control by a voltaic pulse or a pulse repetition rate, according to the diagnostic purpose for a given hypothalamus. Consequently, the efficiency tends to increase. This experiment was conducted at a maximum of 210 W, a magnetic induced amplitude of 0.1~2.5 Tesla, a pulse duration of $200{\sim}350\;{\mu}s$, magnetic inducement of 5 Hz, stimulus frequency of 0.1~60 Hz, and a duration of stimulus train of 1~10 sec.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.15 no.4
• /
• pp.159-166
• /
• 2020

The IBC (Intra-Body Communication) benefits from a wireless communication system for exchanging various kinds of digital information through wearable electronic devices and sensors. The IBC using the human body as the transmission channel allows wireless communication without the transmitting radio frequency waves to the air. This paper discusses the results of experiments on electrostatic coupling IBC based on FSK (Frequency Shift Keying) and 1 bit error correction. We implemented FSK communication and 1 bit error correction algorithm using the MCU boards and aluminum tape electrodes. The transmitter modulates digital data using 50% duty square wave as carrier signal and transmits data through human body. The receiver performs ADC (Analog to Digital Conversion) on carrier signal from human body. In order to figure out the frequency of carrier signal from ADC results, we applied zero-crossing algorithm which is used to detect the edge characteristic in computer vision. Experiment results shows that digital data modulated as square wave can be successfully transmitted through human body by applying the proposed architecture of a 1ch GPIO as a transmitter and 1ch ADC for as a receiver. Also, this paper proposes 1 bit error correction technique for reliable IBC. This technique performs error correction by utilizing the feature that carrier signal has 50% duty ratio. When 1 bit error correction technique is applied, the byte error rate at receiver side is improved around 3.5% compared to that not applied.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1645-1646
• /
• 2006

Micro ElectroMechanical Systems (MEMS) 기술을 이용한 초미세 유체 제어 시스템 (마이크로 펌프, 마이크로 밸브, 마이크로 채널, 마이크로 믹서 등)은 화학, 생명분야의 DNA 분석, 항원-항체 분석, 질병의 진단 등에 사용되는 lab-on-a-chip, micro total analysis system ($\mu$-TAS) 등에서 화학 및 바이오 유체를 제어하는 분석 시스템의 일부분으로서 사용되며 필수적으로 요구된다. 본 논문에서는 이러한 microchip을 구현하기 위해 초미세 유체 제어 소자인 마이크로 펌프와 밸브를 같은 기관 위에 polydimethylsiloxane (PDMS)와 indium tin oxide (ITO)-Glass를 사용하여 동일한 구조로 집적 하였다. 마이크로 펌프의 pumping rate은 인가 직류 펄스 전력의 주파수와 duty 비를 변화시켜 최적화하였다. 직류 펄스 전력 500 mW를 인가하였을 때 주파수 2 Hz, duty 비 7 %에서 약 $1.05{\mu}l/min$의 최대 유량이 측정되었다. 마이크로 밸브는 ITO 히터에 전력을 인가함으로서 유량의 on/off 제어가 잘 됨을 확인할 수 있었고 유체를 closing하기 위해 필요한 전력은 약 300 mW이다.