• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
• /
• pp.1534-1536
• /
• 2005

A DC-DC converter is being widely used for various household appliances and for industry applications. The DC-DC converter is powered from single battery, and the voltage is varied according to the purpose. In the vehicle, various accessories whose electric power is different are being used. Thus, plural number of DC-DC converter should be provided, so these situations bring complicated circuits, and accordingly, higher cost. Under such backgrounds, in this paper, we propose a novel buck-boost chopper circuit with simply configuration which can supply to two or more different output loads. The propose chewer circuit can control output voltages by controlling duty ratio by using typically two switching devices, which is composed by single boost-switch and single buck-switch. The output voltage can be controlled widely. A few modified circuits developed from the fundamental circuit are represented including the general multi-load circuit. And all this merits and appropriateness was proved by computer simulation and experience.

• 한국재료학회지
• /
• 제16권10호
• /
• pp.639-646
• /
• 2006

Over the last two decades, microbiologically influenced corrosion (MIC) of metallic materials has received considerable attention due to its serious effects on industrial field. In this context, it is important to devise control methods which inhibit biofilm formation on various metallic compounds and are compatible with environment. It was change of various conditions (duty cycle, current density, $AgNO_3$ concentration and pH) for injection of Ag particles in anodized Aluminum alloy pore using pulsed current. Optimal condition was obtained by means of FE-SEM, ICP analysis etc. The antibacterial metal's specimen were manufactured under optimal condition and this specimen were tested the antibacterial characterization and anticorrosion characterization. In result of test, we can confirmed that the antibacterial characterization and anticorrosion characterization of the specimens of injected Ag particles in anodized Aluminum alloy pore using pulsed current were better than the anodized Aluminum alloy specimens.

• 드라이브 ㆍ 컨트롤
• /
• 제14권4호
• /
• pp.51-60
• /
• 2017

In this study to develop disaster response robot in complex disaster site, we present the design of hydraulic manipulators for armored robot systems. To this end, we performed voice of customer researches with firefighters and rescue personnel. We created and analyzed the mission scenario of firefighters and rescue personnel in complex disaster situations, and derived the required functions of the robot to successfully perform missions. A heavy-duty, heat resistant, dexterous hydraulic robot manipulators is designed to realize the required functions. The designed robot has been verified through simulations and analysis in terms of the working area of the robot, actuating torques, and temperature analysis.

• 기본간호학회지
• /
• 제4권2호
• /
• pp.193-216
• /
• 1997

The purpose of this research was to understand the structure of the experiences of turnover among hospital nurses. The research question was 'What is the structure of the experiences of turnover among hospital nurses?' The sample consisted of 16 hospital nurses who experienced one or more turnover. The unstructured interview were carried out from July 15. through August 31., 1997. Intervewed by audio-recording and analyzed by Van Kaam's method. There were 361 descriptive expressions and priority classifications. The result summerized as 107 common elements, 38 syntheses of hypothetical definitions and 6 identifications of the structural definition. The structural definitions and hypothetical definitiones were as follows ; 1. There were different views on the turnover intention. Hard task, dissatisfaction of initial expectancy, uncomfortable relationship with doctors, inappriate reward, uncomfortable relationship with workers of other parts, uncomfortable relationship with patients, unreasonable promotion, uncomfortable relationship with co-worker, helplessness, poor environment of working conditions. 2. Motivating factor of turnover can be varied : self development, problem of social support, boring task, problem of relation-ship with the senior, unfair promotion, night duty. 3. Social supportive factors were co-worker support, senior support, self control, family support, time support. 4. There were different views on the job satisfaction. Task, relationship with patient, recognition, professionalism, promotion, working environment, relationship with co-worker, reward.

• 대한안전경영과학회지
• /
• 제17권3호
• /
• pp.1-7
• /
• 2015

The study conducted questionnaire analysis to 413 industrial safety field employees in order to examine the necessity and validity of industrial safety field's 17th neo-job classification based on National Competency standards(NCS). As a result, 50.1% of industrial safety management field and 43.3% of industrial health management field answered that classification details of occupational safety and health management field are classified by job(duty) performance. Industrial safety management field recognizes that management and engineering section play a significant role in their work, while industrial health management field recognizes worker's health care and work environment management and overall control of work environment assessment to be significant in their work. Furthermore, industrial safety management field recognizes that separating qualification and foundation of 'construction safety manager', 'chemicals(safety and health) manager', '(toxic)risk assessment evaluator or risk factor manager' to be highly significant. The study is meaningful in that it suggests industrial safety field's qualification items practical in industrial sites.

• Journal of the Optical Society of Korea
• /
• 제19권3호
• /
• pp.255-259
• /
• 2015

We have proposed and experimentally verified a pulse-width modulation (PWM) generator which directly generated a PWM signal in the optical domain. Output waveforms were clear at the repetition rate of 16 MHz; the duty cycle (DC) was from 14.7% to 72.1%; and the DC-control resolution was about 4.399%/dB. The PWM generator' operation principle is based on the injection-locking property of a single-mode Fabry-$P{\acute{e}}rot$ laser diode (SMFP-LD). The SMFP-LD, which has a self-locked mode wavelength at ${\lambda}_{PWM}$, was used to detect the power of the injection-locking signal (optical analog input). If the analog input power is high, the SMFP-LD is locked to the wavelength of the input signal ${\lambda}_a$ and there is no output after an optical bandpass filter (OBF). If the analog input power is low, the SMFP-LD is unlocked and there is output signal at ${\lambda}_{PWM}$ after the OBF. Thus, the SMFP-LD plus the OBF provide digital output for an analog input. The DC of the output PWM signal can be controlled by tuning the power of the analog input.

• Journal of Power Electronics
• /
• 제19권2호
• /
• pp.380-393
• /
• 2019

Traditional boost converters have difficulty realizing high efficiency and high voltage gain conversion due to 1) extremely large duty cycles, 2) high voltage and current stresses on devices, and 3) low conversion efficiency. Therefore, a function decoupling high voltage gain DC/DC converter composed of a DC transformer (DCX) and an auxiliary converter is proposed. The role of DCX is to realize fixed gain conversion with high efficiency, whereas the role of the auxiliary converter is to regulate the output voltage. In this study, different forms of combined high voltage gain converters are compared and analyzed, and a structure is selected for the function decoupling high voltage gain converter. Then, topologies and control strategies for the DCX and auxiliary converter are discussed. On the basis of the discussion, an optimal design method for circuit parameters is proposed, and design procedures for the DCX are described in detail. Finally, a 400 W experimental prototype based on the proposed optimal design method is built to verify the accuracy of the theoretical analysis. The measured maximum conversion efficiency at rated power is 95.56%.

• 한국멀티미디어학회논문지
• /
• 제25권2호
• /
• pp.145-156
• /
• 2022

Nowadays, the complexity of object tracking models among hardware applications has become a more in-demand duty to complete in various indeterminable environment tracking situations with multifunctional algorithm skills. In this paper, we propose a virtual city environment using AirSim (Aerial Informatics and Robotics Simulation - AirSim, CityEnvironment) and use the DQN (Deep Q-Learning) model of deep reinforcement learning model in the virtual environment. The proposed object tracking DQN network observes the environment using a deep reinforcement learning model that receives continuous images taken by a virtual environment simulation system as input to control the operation of a virtual drone. The deep reinforcement learning model is pre-trained using various existing continuous image sets. Since the existing various continuous image sets are image data of real environments and objects, it is implemented in 3D to track virtual environments and moving objects in them.

• 항공우주의학회지
• /
• 제30권1호
• /
• pp.40-49
• /
• 2020

In accordance with ICAO SARPs, the states should implement appropriate aviation-related health promotion for airmen subject to an aviation medical examination to reduce future medical risks to flight safety. We aimed to analyze the results of the aviation medical examination to use as objective evidence for establishing an aviationrelated health promotion plan. The results of the final issuance of airmen medical certificate from 2015~2017 were collected from the e-sky computer system. The 30 cases (0.3%) in 2015, 22 cases (0.2%) in 2016, 38 cases (0.3%) in 2017 were unfit for flight duty. The 34 unfit out of the total 90 cases were renewal physical examinations. The cardiovascular disease was most commonly in 11 cases, followed by 8 tumors, 4 psychiatric diseases, 3 ophthalmic diseases, 2 respiratory diseases, 2 neurologic diseases, 2 otolaryngological diseases, 1 endocrine disease and 1 digestive disease. The results of this study can be used as objective data in aviation-related health promotion plan. The health promotion activities based on objective data can contribute to improving aviation safety by improving the lifestyles of airmen.

• Safety and Health at Work
• /
• 제8권1호
• /
• pp.36-41
• /
• 2017

Background: Police work is generally sedentary although there may be situations that require physical endurance and strength, such as foot chases and arresting suspects. Factors such as excessive body fat can impede an officer's physical ability to deal with such occurrences. Our objective was to examine associations between officers' body fat percentage (BF%) and performance on a standardized fitness protocol. Methods: Data were obtained from fitness screening among 1,826 male and 115 female officers in a large US police agency. The screening consisted of a 2.4-km run, push-ups, sit-ups, and sit-and-reach test. Sex-specific body fat percentages were estimated from skinfold thickness measured using calipers. Linear regression models were used to examine unadjusted and adjusted mean scores of fitness tests across BF% tertiles. Results: The prevalence of overall fitness was 4.3 times greater in male officers and 3.6 times greater in female officers having the lowest BF% tertile compared with the highest tertile (30.3% vs 7.1% and 46.0% vs 12.8%, respectively). BF% was linearly and positively associated with the time of 2.4-km run (p < 0.001), and linearly and inversely associated with the number of push-ups (p < 0.001), sit-ups (p < 0.001), and the distance of sit-and-reach (p < 0.001) in men. Similar associations were observed in women with the exception of sit-and-reach (p = 0.122). Associations were independent of age, race/ethnicity, rank, and duty station. Conclusion: Overall, BF% was inversely associated with fitness levels in male and female officers. Future longitudinal studies should be initiated to explore the potentially causal relationship between BF% and fitness in law enforcement officers.