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  • Title/Summary/Keyword: light cycle

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A study on the radiation effect of silicon solar cells in a low Earth orbit satellite by using high energy electron beams (고에너지 전자빔을 이용하여 저궤도 인공위성의 실리콘 태양센서의 내방사선 특성 연구)

  • Chung, Sung-In;Lee, Jae-Jin;Lee, Heung-Ho
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.45 no.3
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    • pp.1-5
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    • 2008
  • This paper analyzes on the radiation effect of silicon solar cells in a low Earth orbit satellite by using high energy electron beams. Generally, the satellite circling round in a low orbit go through Van Allen belt, in which electronic components are easily damaged and shortened by charged particles moving in a cycle between the South Pole and the North Pole. For example, Single Event Upset (SEU) by radiation could cause electronic devices on satellite to malfunction. From the ground experiment in which we used the high energy electron beam facility at Knrea Atomic Energy Research Institute (KAERI), we tried to explain sun sensor degradations on orbit could he caused by high energy electrons. While we focused on the solar cells used for light detectors, We convince our research also contributes to understand the radiation effect of solar cells generating electric powers on satellites.

Observation of long-term disappearance and reappearance of the outer radiation belt

  • Lee, Dae-Young;Shin, Dae-Kyu;Kim, Kyung-Chan;Kim, Jin-Hee;Cho, Jung-Hee;Park, Mi Young;Angelopoulos, Vassilis;Hwang, Junga;Lee, Yonghee;Kim, Thomas
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.115.2-115.2
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    • 2012
  • In this study we have used the data of various instruments onboard the THEMIS spacecraft to study the characteristics of the outer radiation belt during the ascending phase of solar cycle 24. The most astonishing result is that we discovered four long-term (a month or so) periods during which the belt has nearly disappeared. The first disappearance started late 2008, followed by reappearance in ~a month, and three more similar events repeated until early 2010 when the belt has reappeared. This is well revealed at 719 keV electrons, which is the currently available uppermost energy channel from the THEMIS SST observation, but also seen at even lower energies. Overall consistent features were confirmed using the NOAA-POES observations. The vanished belt periods are associated with extremely weak solar wind conditions, low geomagnetic disturbances (in terms of Kp and AE/AL), greatly suppressed wave (ULF and chorus) activities, greatly reduced storm and substorm activities (little source particle supply), and expanded plasmapause locations. The direct observations of such events shed light on the fundamental question of the origin of the radiation belt, which is the main focus of our presentation.

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Effects of Physical Activity and Melatonin in a Rat Model of Depression Induced by Chronic Stress (자유로운 신체운동과 멜라토닌이 우울장애 동물모델에 미치는 효과)

  • Seong, Ho Hyun;Jung, Sung Mo;Kim, Si Won;Kim, Youn Jung
    • Journal of Korean Biological Nursing Science
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    • v.17 no.1
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    • pp.37-43
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    • 2015
  • Purpose: Stress, depending on its intensity and duration, results in either adaptive or maladaptive physiological and psychological changes in humans. Also, it was found that stressful experiences increase the signs of behavioral despair in rodents. On the other hand, exercise and melatonin treatment is believed to have many beneficial effects on health. Thus, this study was designed to evaluate the anti-depressant effects of physical activity and melatonin against chronic stress-induced depression in rats. Methods: Adult male Sprague-Dawley(SD) rats(200-250g, 7 weeks of age) were subjected to depression induced by chronic stress. Chronic depression was induced with forced-swim stress (FSS) and repeated change of light-dark cycle for 4 weeks. In the last 2 weeks, some rats were confined in a cage enriched with a running wheel, seesaw and chewed a ball from 19:00 to 07:00 every day. Melatonin was injected intra-peritoneally (I.P), and the rats received intraperitoneal injections of melatonin (15 mg/kg). The Forced Swim Test (FST) was performed to evaluate the immobility behaviors of rats for a 5 min test. Results: It was found that, the immobility time in FST was significantly (p<.05) lower in physical exercise (M=58.83±22.73) and melatonin (M=67.33±37.73) than in depressive rats (M=145.93±63.16) without physical activity. Also, TPH positive cell in dorsal raphe was significantly (p<.05) higher in exercise (M=457.38±103.21) and melatonin (M=425.38±111.56) than in depressive rats (M=258.25±89.13). Conclusion: This study suggests that physical activity and melatonin produces antidepressant-like effect on stress-induced depression in rats. So, physical exercise and melatonin may be a good intervention in depression patients.

A Study on Shot peening on Fatigue Crack Growth Property for Marine Structural Steel (해양구조용강의 피로거동에 관한 연구)

  • Park, Kyoung-Dong;Ha, Kyoung-Jun
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.05a
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    • pp.313-318
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    • 2003
  • The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress(in this thesis). The compressive residual stress was imposed on the surface according to each shot velocity(57, 70, 83, 96 m/sec) based on Shot-peening, which is the method of improving fatigue lift: and strength. By using the methods mentioned above, I arrived at the following conclusions 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. And in stage I, ΔKth, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

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Gait Type Change for Decrease of Leg's Fatness (다리의 지방감소를 위한 보행형태 변화에 관한 연구)

  • Bae, Sung-Soo;Lee, Hea-Deok;Oun, Jung-Young;Yoon, Chang-Goo;Choi, Houng-Sik
    • Journal of Korean Physical Therapy Science
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    • v.4 no.1
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    • pp.303-313
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    • 1997
  • We developed the shoes which is specially designed to decrease the leg's fatness during walking and to improve the body figure. The analysis of the gait cycle and the shoes gave changes at the swing phase. We examined the results to 30 girl students of Yeong Dong Junior College for 5 weeks from 27, October to 29, Nobember in 1996, and the results were also obtained in decrease of their thigh's size in circumference. The results of the analysis are as followings; 1) After experiment circumference of the right thigh was decreased 0.04cm in noncontrol group and significantly decreased 1.04 cm in control group(p<0.01). 2) After experiment circumference of the left thigh was decreased 0.27 cm in noncontrol group and significantly decreased 1.17cm in control group(p<0.01). 3) After experiment circumference of the right calf of the leg decreased 0.09 cm in noncontrol group and significantly decreased 0.54 cm in control group(p<0.01). 4) After experiment circumference of the left calf of the leg decreased 0.21 cm in noncontrol group and significantly decreased 0.47 cm in control group. 5) After experiment body weight were not changed significantly in both group. In these results, if the people want to exercise the analysis of fat in the thigh, put on the shoes which improves the body figure and do daily work, and it will be naturally decreased the fat in thigh and they will maintain the beauty lines of the legs. There weren't any changes in the body weight while the fat of thigh in circumsference was analysed and decreased. It means that because the weight of the fat is very light, there weren't any changes in body weight.

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Development of an Organic Scintillator Sensor for Radiation Dosimetry using Transparent Epoxy Resin and Optical Fiber (투명 에폭시와 광섬유를 이용한 방사선량 측정용 유기섬광체 센서 개발)

  • Park, Chan-Hee;Seo, Bum-Kyoung;Lee, Dong-Gyu;Lee, Kune-Woo
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.7 no.2
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    • pp.87-92
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    • 2009
  • Remote detecting system for a radiation contamination using a plastic scintillator and an optical fiber was developed. Using a commercially available silica optical fiber and a plastic scintillator, we tested then for a real possibility as a remote monitoring detector. Also, a plastic scintillator was developed by itself, and evaluated as a radiation sensor. The plastic scintillator was made of epoxy resin, a hardener and an organic scintillation material. The mixture rate of the epoxy resin, hardener and organic scintillator was fixed by using their emission spectrum, transmittance, intensity etc. In this study, in order to decrease the light loss of an incomplete connection between an optical fiber and a scintillator, the optical fiber was inserted into the scintillator during the fabrication process. The senor used a plastic optical fiber and was estimated for its detection efficiency by an optic fiber's geometric factor.

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A Study on the Resistance Welding of Metallic Sandwich Panel : Part 1 - Determination of Process Parameters (저항 용접을 이용한 금속 샌드위치 판재 접합에 관한 연구 : Part 1 - 공정변수의 선정)

  • Lee Sang-Min;Kim Jin-Beom;Na Suck-Joo
    • Journal of Welding and Joining
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    • v.23 no.6
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    • pp.49-54
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    • 2005
  • Inner Structured and Bonded(ISB) panel, a kind of metallic sandwich panel, consists of two thin skin plates bonded to a micro-patterned inner structure. Its overall thickness is 1\~3mmand it has attractive properties such as ultra-lightweight, high efficiency in stiffness-to-weight and strength-to-weight ratio. In many previous studies, resistance welding, brazing and adhesive bonding are studied for joining the panel. However these methods did not consider productivity, but focused on structural characteristics of joined panels, so that the joining process is very complicated and expensive. In this paper, a new joining process with resistance welding is developed. Curved surface electrodes are used to consider the productivity and the stopper is used between electrodes during welding time to maintain the shape of inner structure. Welding time, gap of electrodes and distance between welding points are selected as the process parameters. By measuring the tensile load with respect to the variation of welding time and gap of electrodes, proper welding conditions are studied. Welding time is proper between 1.5-2.5cycle. If welding time is too long, then inner structures are damaged by overheating. Gap of electrode should be shorter than threshold value fur joint strength, when total thickness of inner structure and skin plate is 3.3mm, the threshold distance is 3.0mm.

Blast Design for Controlled Augmentation of Muck Pile Throw and Drop (발파석의 비산과 낙하를 조절하기 위한 발파 설계)

  • Rai, Piyush;Yang, Hyung-Sik
    • Tunnel and Underground Space
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    • v.20 no.5
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    • pp.360-368
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    • 2010
  • The paper presents a case study from a surface mine where the controlled augmentation of throw and drop of the blasted muck piles was warranted to spread the muck piles on the lower berm of the bench. While the augmentation of throw increased the lateral spread and the looseness of the broken muck, the augmentation of drop significantly lowered the muck pile height for easy excavation by the excavators. In this light, the present paper highlights and discusses some pertinent changes in the blast design parameters for such specialized application of cast blasting in a surface mine, where a sandstone bench, with average height of 22-24 m was to be made amenable for excavation by 10 m3 rope shovels, which possessed maximum digging capability of up to 14 m. The results of tailoring the blast design parameters for augmentation of throw and drop are compared with the baseline blasts which were earlier practiced on the same bench by dividing the full height of the bench in 2-slices; upper slice (10-14 m high) and lower slice (12-15 m high). Results of fragment size, its distribution and total cycle time of excavator (shovel) are presented, and discussed.

Circadin Gibberellins production in Sorghum (수수에서 식물호르몬 지베렐린의 circadian 리듬)

  • 이인중;김길웅;김경민
    • Journal of Life Science
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    • v.7 no.3
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    • pp.205-211
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    • 1997
  • The possibility of circadian production of plant hormone gibberellin (GA0 was examined in phytochrome B mutant (plyB-1) and wild-type sorghum. GA12, GA20 and GA1 levels were found to cycle circadianly in both phyB-1 and wild-type. The periods (33 h) of GA20 and GA1 cycling in constant light were longer than normal photoperiods in both genotypes and typical average free running periods in plants of 22 to 28 h. The biological clock was thus shown to function properly in phyB-1. However, circadian regulation of GAs productions were not clear as compared to circadian ethylene regulation reported by Lee (1996). Although, in sorghum, EOD FR treatment hasten floral inititation, the differences in GA concentrations between treatments and untreated control were generally less dramatic than expected. Thus, it can be concluded that FR does not act primarily by changing absolute levels of GAs but rather by increasing flowering responsiveness to GAs.

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A Study on a KTP Crystal Laser System for a Cancer Using P.D.T. (KTP 크리스탈을 이용한 PDT용 레이저 시스템 개발)

  • Kim, Byoung-Mun;Nam, Hyo-Duk;Kim, Byoung-Chul
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07b
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    • pp.631-634
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    • 2004
  • The method that exists in Photodynamic Therapy uses Photosensibility drug strongly Influencing tumour accumulation together with photochemical laser effect and makes the structure of tumour be localized and become extinct. The intracavity transformation of the Nd :YAP main radiation 1079 nm was Raman converted in barium nitrate crystal and the Stokes frequency (1216 nm) was doubled using KTP or RTA crystals. The LiF or Cr:YAG crystals are used for the Q-switch. The radiation Parameters were obtained at 100 Hz pump repetition frequency. The average power at 608 nm radiation with LiF and KTP was 700 mW at multi-mode generation. The 3-6 single 10-15 ns pulses were generated during one cycle of pumping. The doubling efficiency with RTA was two times more than with KTP. The cells of Ehrlich adenocarcinoma (0.1 ml) were i.m. implanted in hind thighs of ICR white non-imbred mice. The cells were preliminarily diluted in medium 199 in the ratio of 1 to 5. HpD was intravenous administered in a dose of 10 mg/kg. The left clean-shaven hind leg was irradiated with laser light 21-27 hours after the administration of the preparation. The right non-Irradiated leg of each animal served as a control. The animals with the transplanted tumor that were not injected with HpD sewed as a control to estimate the complex effect (HpD+ irradiation). Before the administration of HpD and on 3 and 4 days after irradiation the tumor size was measured and the percent of the tumor growth inhibition was calculated. The results of animal treatments has shown high efficiency of PDT method for cancer treatment by means 0.608 m high power pulse solid state laser.

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