• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.139-144
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• 2005

Because of the photorefractive recording dynamics, each newly recorded hologram partially erases all previously stored image. Thus achieving the desired diffraction efficiency profile for the entire sequence after all images have been recorded requires exposure time schedule. The often cited classical exposure-schedule model predicts a rising-exponential build-up and an exponential decay in An with an exposure time. However because we cannot directly measure the An, it's difficult to establish the relation of both. In this paper, we deduce the relation of diffraction efficiency and exposure time from experiment data and suggest an algorithm to make time schedule profile in angle/fractal multiplexing of holographic data storage. After that, we present simulated result with equal hologram diffraction efficiency for a sequence of 250 holograms recorded by angle/fractal multiplexing.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.132-135
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• 2002

In this paper, a new method to implement the photopolymer-based VHOE using the optimized exposure time schedule is proposed. The cumulative grating strength dependence on the exposure energy is mathematically modeled by using the fourth-order polynomial function and then using this model, the optimized exposure-time schedule of the photopolymer for recording the given multiple gratings is calculated.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.883-886
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• 2002

A new exposure time scheduling scheme to implement the optimized photopolymer-based VHOE is proposed and using this method, the 8-view VHOE system is experimentally developed. The CGS dependence on the exposure energy is mathematically modeled using the fourth-order polynomial function and using this model optimized exposure-time schedule for recording the given multiple gratings in the photopolymer is calculated. In addition, basing on this suggested exposure-time schedule, 8-view VHOE is finally implemented and its performance is discussed.

• 전자공학회논문지D
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• 제36D권10호
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• pp.61-70
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• 1999

본 논문에서는 균일한 다중 홀로그램을 얻기 위한 몇 가지 노출 시간 계획을 분석하고 실험을 통해 $LiNbO_3$:Fe(0.015wt%) 결정에 기록된 홀로그램의 회절 효율을 측정하였다. 높은 각도 분해능을 갖는 시스템 (최소 각도 : $0.0028^{\circ}$)을 이용하여 두 입사빔의 세기비와 최소 단위의 다중화 각도가 정밀하게 조사되었다. 초기 기록시간, 전체 노출시간, 그리고 시간상수를 고려하여 100개의 회절분포(0.014 ${\pm}$ 0.005%)를 측정하였으며, 330개의 아날로그 영상을 동일한 장소에 기록하였다. 또한 공간 다중화를 통해 총 500개 이상의 홀로그램이 재생되었다.

• The Korean Journal of Physiology and Pharmacology
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• 제2권6호
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• pp.677-685
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• 1998

To investigate the effects of neonatal stress on behavior and neurochemistry, rats were exposed to the footshock stress on postnatal day (PND) 14 or PNDs 14 and 21. Rats were exposed to uncontrollable electric shocks delivered to the floor with a constant current (0.8 mA) for 5 sec period. Daily sessions consisted of 60 trials on a random time schedule with an average of 55 sec. The first exposure to footshocks on PND 14 decreased body weight gain for 1 day. However, the second exposure to footshocks on PND 21 did not affect body weight gain. Exploratory activity was measured by exposing a rat to a novel environment 24 h after experience of footshocks. Similar to the body weight changes, a decreased activity was noted after the first exposure to footshocks, while no changed activity was noted after the second exposure to footshocks. However, the Bmax value of $5-HT_{2A/2C}$ receptors in the cortex decreased by the second exposure to footshocks, but not by the first exposure to footshocks. Moreover, an autoradiographic study revealed that the density of $[^3H]dexamethasone$ binding in hippocampus decreased in rats exposed to footshocks 4 times during PND $14{\sim}20.$ These results suggest that the uncontrollable footshock stress changes 5-hydroxytryptamine and glucocorticoid receptor systems acutely and that the repeated exposure to the same stress may not elicit behavioral alterations by the compensatory activity of young brain although changes in some neurochemistry exist.

• 한국식품위생안전성학회지
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• 제11권4호
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• pp.227-234
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• 1996

This study was designed to characterize endotoxin-induced prostaglandin production in primary cultured rat vascular smooth muscle cells (VSMC). The time course for prostaglandin synthesis in lipopolysaccharide (LPS)-stimulated VSMC showed that the maximum production was reached in 12 hours. LPS induced prostaglandin H2 synthase (PGHS) activity in VSMC and the time course profile in the changes of PGHS activity paralleled that of total prostaglandin production. Differential treatment showed that 4 hours' exposure to LPS was enough for the maximum effect on the prostaglandin production and this effect was completely inhibited by the co-treatment of actinomycin D, a transcription inhibitor. These results suggest that LPS effect might be determined within 4 hours. Actinomycin D increased PGHS activity without affecting prostaglandin production if added 4 hours after LPS treatment. On the other hand, cyclogeximide, a translation inhibitor, augmented LPS-induced prostaglandin production if treated during first four hours, but it inhibited LPS-induced PGHS activity regardless of treatment schedule. These results suggest the existence of multiple regulating mechanisms in the LPS-induced prostaglandin synthesis.

• 한국산업보건학회지
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• 제34권1호
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• pp.8-13
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• 2024

Objectives: To evaluate the levels of exposure to organic compounds during aircraft disinfection and seat cover replacement operations. Methods: According to the working schedule, organic compounds were collected using activated carbon tubes and then analyzed by GC/FID and GC/MSD. Results: In the disinfection task, the main substances listed in the material safety data sheet (MSDS) of the disinfectant were not detected. However, 1-bromopropane, which had been used in the previous task of replacing seat covers, was detected at a level of 2.37 ppm at the measurement time. During seat cover replacement, bonding workers were exposed to 2.48 ppm on an eight-hour time-weighted average, and seat cover replacement workers were exposed to 0.22 ppm. Conclusions: It is necessary to ensure the reliability of MSDS. A work environment management system is necessary when different companies alternate working in the same place.

• 생물정신의학
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• 제6권2호
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• pp.240-245
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• 1999

Object : This study was designed to evaluate the effects of olanzapine on the schedule-induced polydipsia(SIP) which is one of animal model of obsessive-compulsive disorder in rats. We administered olanzapine as a serotonin and dopamine blocking agent, fluoxetine as a selective serotonin reuptake inhibitor, and haloperidol for the dopamine antagonist to rats which showed schedule-induced polydipsic behavior. Methods : Spraque-Dawley rats weighing 200-250gm were individually housed and maintained and allowed free access to water. The rats were placed on a restricted diet. To induce polydipsia, rats were placed in the cage where a pellet dispenser automatically dispensed 90mg pellets on a fixed-time 60 seconds(FT-60s) feeding schedule over 150 minute test session per day. Water was available at all times in the cage. After 4 weeks of daily exposure to the FT 60s feeding schedule, experimental rats met a predetermined criterion for polydipsic behavior(greater than 3 times of water per session on average). 5 groups of rats were administered olanzapine(3mg/kg, i.p), olanzapine(10mg/kg, i.p), fluoxetine(5mg/kg, i.p.), haloperidol(0.1mg/kg, i.p.), and vehicle(1cc/kg, i.p.) for 3 weeks. The rats were tested once a week to access schedule induced polydipsic behavior. Water bottles were weighed before and after the 150-minute test session. The chronic effects of administration of experimental drugs on schedule induced polydipsic behavior were analyzed with ANOVA and Scheffe test as a posthoc comparison. In order to measure water consumption in non-polydipsic food-deprived rats, a separate group of rats(N=8) were individually housed and given a single bolus(14.5gm) of food per day which maintained them at their average body weight. Results and Conclusion : The results were as follows ; 1) After 4 weeks of scheduled feeding procedure, the experimental group showed significant differences than the bolus control in the amount of water consumption as compared with their average water intakes for 4 weeks. At the same periods, there were no differences between the experimental group and the bolus control in the body weight. 2) The fluoxetine group showed significant decrease in the amount of water intake over the 3 weeks of drug treatment as compared with their average amount of polydipsic water intakes. The olanzapine 3mg group showed significant decrease in the amount of water intake at 3rd weeks of drug treatment as compared with their average amount of polydipsic water intakes. The olanzapine 10mg group showed significant decrease in the amount of water intake at 2nd and 3rd weeks of drug treatment as compared with their average amount of polydipsic water intakes. However, the haloperidol group and the vehicle control group showed no changes of amounts of water intake for 3 weeks of treatment as compared with their average amount of polydipsic water intakes. 3) The fluoxetine group showed significantly lower amounts of water intake than the haloperidol group at 2nd weeks of drug treatment. And also the fluoxetine group showed significantly lower amounts of water intake than the haloperidol group and the vehicle control at 3rd weeks of drug treatment. The olanzapine 3mg group and the olanzapine 10mg group showed significantly lower amounts of water intake than the haloperidol group and the vehicle control at 3rd weeks of drug treatment. Above findings suggest that the fixed time feeding procedure for schedule-induced polydipsia as an animal model of obsessive compulsive disorder was effective to the evaluation of pharmacological challenge study. The authors assume that the serotonin hypothesis and the serotonin-dopamine interaction hypothesis are preferred to the dopamine hypothesis in the biological etiology of obsessive-compulsive disorder.

• 한국산업보건학회지
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• 제21권3호
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• pp.156-161
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• 2011

Objectives: Tetrahydrofuran (THF) is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. THF has been used as a solvent and a precursor for various syntheses of polymers. However, THF is known to irritate to the eyes, skin and mucus membranes. Overexposure by inhalation, ingestion or skin contact may produce nausea, dizziness, headaches, respiratory irritation and possible skin burns. The purpose of this study is to evaluate of the worker exposure and characteristics of workers in the workplaces that use or manufacture THF. Methods: Sixteen factories in Korea, which manufacture or use THF, were selected for this study and a total of 130 air samples including 104 time-weighted average (TWA) samples and 26 short-term exposure limit (STEL) samples, were collected. Air samples were collected with charcoal tube (100mg/50mg) and analyzed by gas chromatograph/flame ionization detector(GC/FID). Results: The TWA concentration of THF was 16.05ppm (GM) at PS script printing, 2.32ppm (GM) at PVC stabilizer, 1.03ppm (GM) at Lithium triethylborohydride, 0.63ppm (GM) at Polytetramethylene ether glycol(PTMEG), 0.42ppm (GM) at Manufacturing THF, 0.13ppm (GM) at Glue and 0.12ppm (GM) at synthetic rubber/resins. Two out of sampes for PS script printing exceeded 50ppm as 8-hour exposure limit of MOEL. The short term exposure to THF was 54.77ppm (GM) at PS script printing, 17.10ppm (GM) at PTMEG, 13.76ppm (GM) at Manufacturing THF, 2.86ppm (GM) at Lithium triethylborohydride, 0.87ppm (GM) at synthetic rubber/resins and 0.13ppm (GM) Glue. We found that the highest exposure process for both the TWA and STEL samples was PS script process. Two samples exceeded 100ppm as short term exposure limit of Ministry of Employment and Labor(MOEL). Conclusions: Characteristic of STEL concentration for THF is considerably different from TWA concentration in workplaces because workers could exposure high concentration of THF in a moment when they work irregularly schedule. So exposure controls for momentary works have to be prepared, and considered the skin absorption and inhale of THF.

• Journal of the Optical Society of Korea
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• 제1권1호
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• pp.19-22
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• 1997

The photorefractive properties of 4% mol magnesium oxide doped lithium niobate have been investigated at room temperature. The recording and erasing time constants were measured as a function of intensity and analyzed by using the two active species (electron-hole) model. The results were used to compute the exposure schedule for multiple hologram recording. We have recorded grating of five holograms by angular multiplexing at room temperature and fixed them by means of a thermal cycling procedure. The highest diffraction efficiency of a fixed grating is up to 50% of an unfixed one.