• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.283-293
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• 2014

The purpose of this study is to understand baby boomers' perception of and preparation for later life by analyzing essays from 80,000 hours design competition. The researchers were able to access to 62 baby boomers' essays and used thematic analysis. The results showed that the competition enabled participants to re-conceptualize the meaning of preparation for later life. Three characteristics were derived in the participants' designing their future: 1) life focused on themselves, 2) life in which work, relationship, and leisure are balanced, 3) community life which take social responsibility. All the participants stressed health and learning as key factors in preparing for later life. They also showed almost obsessiveness toward their own effort to be diligent in order to achieve their idealistic later life. Based on the findings, practical implications for preparation for later life among baby boomers are discussed.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.214-219
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• 2023

Considering the case in the United States where most nuclear power plants with an initial design life of 40 years continue to operate until 60 or 80 years after undergoing material soundness evaluation, it is time to plan a more robust long-term operation strategy for nuclear power plants in Korea. There are some reports that SRO/LRO might be formed when Alloy 690 is heat treated for 10,000 hours to 100,000 hours at 360 to 450 ℃. The possibility of LRO formation in Alloy 690 steam generator tubings of Kori nuclear power plant unit 1 (Kori-1) was investigated using existing research papers. The mechanism in which SRO/LRO occurred was also surveyed. Alloy 690 was found to be more likely to cause ordering than Alloy 600 in terms of alloy composition. The ordering could be evaluated through changes in material properties. However, it is difficult to evaluate it from a microstructural point of view. The likelihood of LRO in Alloy 690 of the Kori-1 plant operated at 320 ℃ for 19 years seemed to be low in terms of time and exposure temperature.

• Journal of Information Display
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• v.8 no.2
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• pp.10-14
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• 2007

A blazed $GxL^{TM}$ device is described as having high optical efficiency (> 70% for RGB lasers), and high contrast ratio (> 10,000:1), and that is highly reliable when used in a large-area laser projection system. It has a robust design and precise stress control technology to maintain a uniform shape (bow and tilt) of more than 6,000 ribbons, a $0.25-{\mu}m$ CMOS compatible fabrication processing and planarization techniques to reduce fluctuation of the ribbons, and a reliable Al-Cu reflective film that provided protection against a high-power laser. No degradation in characteristics of the GxL device is observed after operating a 5,000- lumen projector for 2,000 hours and conducting 2,000 temperature cycling tests at $-20^{\circ}C$ and $+80^{\circ}C$. At the 2005 World Exposition in Aichi, Japan the world's largest laser projection screen with a size of 2005 inches (10 m ${\times}$ 50 m) and 6 million pixels (1,080 ${\times}$ 5,760) was demonstrated.

• Journal of the Korean Society for Railway
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• v.18 no.2
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• pp.111-116
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• 2015

LED luminaires as a lighting system have attracted much research attention due to their high efficiency and long lifetimes. However, disappointing outcomes have been noted in terms of performance levels and lifetimes as compared to desired system requirements in practice due to certain electrical and thermal characteristics of LEDs. LM-80 and TM-21 established by IESNA are the best known standards for lifetime test procedures and estimation techniques. However, they only handle LED light sources without guaranteeing the LED luminaire in a reliability test. They also operate for more than 6,000 hours and undergo various stresses, such as the operating current and temperature. Therefore, a lifetime standard for LED luminaires has not yet been established. This paper proposes a conceptual design of a lifetime test system for LED headlamps depending on the operating environment. Eventually, this method can assist with evaluations of the validity of lifetime standard tests of LED headlamps.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.84-94
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• 2013

In case when the existing TRIAC phase controlled dimmer is drove for the LED lighting equipments, there are many problems such as the LED flicker in low phase-angles, the acoustic noise and elements damage by increase of the peak voltage in the input filter capacitor, mulfunction by insufficiency of the TRIAC holding current, and the abnormal oscillation by LC resonant. In this paper, we proposes the single-stage quasi-resonant PSR(Primary Side Regulation) PWM converter, and the design, the simulation and experiment are performed. As a result, it could confirm that the proposed PWM converter is the lighting equipments for LED drive which can alternate the existing 60W class incandescent bulbs and it has the high drive performance of the efficiency 80% and over, the power factor 0.95 and over under the normal voltage 220V. Finally, total harmonic distortion(THD) is gratified with a standard[1] of the lighting equipments and the durability is evaluated as the high reliablilty of 150,000 hours and over.

• Korean Parent-Child Health Journal
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• v.6 no.2
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• pp.127-146
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• 2003

The purpose of this study is to investigate the seven-hour sexuality education program for senior high school girl students and apply it to them to find out how this program affects their sex-related knowledge, sexual attitudes, and the self-efficacy of sexual behavior practice. The ultimate goal of this study is that high school girl students are to prevent unwanted pregnancy, STD and AIDS, after attending this sexuality education program. A non-equivalent control group pretest-post test design was used for this study. The number of experimental group consisted of 80 girl students and the control group was composed of 80 girls, too. A total of 160 freshmen from two commercial girls' high schools were selected by a convenience sampling method. This study was carried out in commercial high schools located in Daejeon, Korea from July 15th to October 31st, 2002. To discover the need for sexuality education, the researcher surveyed with a pre-designed questionnaire to 160 girls from the two different commercial high schools. The sex education curriculum was developed on the basis of the need of high school girl students for sex education survey results and literature review and a teaching-learning planning model and health belief model. The experimental group was taught the sexuality education program for seven hours from October 19th to 23rd, 2002 and each period continued for 50 minutes. The SPSS(10.0) Windows statistics software was used to analyze the data, along with frequency, percentage, $X^2$-test, t-test, and paired t-test. The instruments' internal consistencies were tested by Cronbach's alpha coefficient. The results of this study were as follows: 1. The increment of sex-related knowledge score after seven hour sexuality education was significantly higher in experimental group (t=-10.88, p=.000). 2. The increment of sex-related attitude score after seven hour sexuality education was significantly higher in experimental group (t=-2.67, p=.009). 3. The increment of the practice of self-efficacy of sexual behavior score after seven hour sexuality education was significantly higher in experimental group(t=-4.95, p=.000). In conclusion, sexuality education programs based on high girl students' educational desire, characteristics of development, a teaching learning planning model, a health belief model were effective to improve sex-related knowledge, sexual attitudes and the self-efficacy of sexual behavior practice of commercial high school girl students. This result can contribute to expand the school nurse's role in the sex education area and to develop theory-based school health nursing.

• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.775-784
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• 2023

With the increasing trend of extreme rainfall that exceeds the design frequency of man-made structures due to extreme weather, it is necessary to review the safety of agricultural reservoirs designed in the past. However, there are no local government-managed reservoirs (13,685) that can be discharged in an emergency, except for reservoirs over a certain size under the jurisdiction of the Korea Rural Affairs Corporation. In this case, it is important to quickly deploy a mobile siphon to the site for preliminary discharge, and this study evaluated the applicability of a mobile siphon with a diameter of 200 mm, a minimum water level difference of 6 m, 420 (m²/h), and 10,000 (m²/day), which can perform both preliminary and emergency discharge functions, to the Yugum Reservoir in Gyeongju City. The test bed, Yugum Reservoir, is a facility that was completed in 1945 and has been in use for about 78 years. According to the hydrological stability analysis, the lowest height of the current dam crest section is 27.15 (EL.m), which is 0.29m lower than the reviewed flood level of 27.44 (EL.m), indicating that there is a possibility of lunar flow through the embankment, and the headroom is insufficient by 1.72 m, so it was reviewed as not securing hydrological safety. The water level-volume curve was arbitrarily derived because it was difficult to clearly establish the water level-flow relationship curve of the reservoir since the water level-flow measurement was not carried out regularly, and based on the derived curve, the algorithm for operating small and medium-sized old reservoirs was developed to consider the pre-discharge time, the amount of spillway discharge, and to predict the reservoir lunar flow time according to the flood volume by frequency, thereby securing evacuation time in advance and reducing the risk of collapse. Based on one row of 200 mm diameter mobile siphons, the optimal pre-discharge time to secure evacuation time (about 1 hour) while maintaining 80% of the upper limit water level (about 30,000 m²) during a 30-year flood was analyzed to be 12 hours earlier. If the pre-discharge technology utilizing siphons for small and medium-sized old reservoirs and the algorithm for reservoir operation are implemented in advance in case of abnormal weather and the decision-making of managers is supported, it is possible to secure the safety of residents in the risk area of reservoir collapse, resolve the anxiety of residents through the establishment of a support system for evacuating residents, and reduce risk factors by providing risk avoidance measures in the event of a reservoir risk situation.