• Clinical and Experimental Reproductive Medicine
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• v.13 no.2
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• pp.95-100
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• 1986

During the past decade great advance has been made in contraceptive technology. The development and subsequent modification of oral steroid contraceptive together with the improved design of other contraceptives have tremendously altered the contraceptive practise of complete throughout the world. At the present time one of most complex issue is the population explosion. In Korea the population growth rate is remarkably decreased from 3% in 1960s to 1.7% in 1984. Increasing proportion of women practising family planning and improved contraceptive methods have contributed on remarkable reduction of fertility rate. But still about half of married women not involved in family planning practise. One of the reasons why that so many women haven't participated in family planning should be undesirable side effects or inconvenience of currently available contraceptives. So we need more research to develop newer, safer and more effective contraceptive to solve the problems. According to recent report on the family planning program achievement in Korea, sterilization (male and female) is most popular, leading contraceptive method (330 cases/1000 fertile persons) and the I.U.D. (167.5/1000), condom (132.9/1000) and oral pill (61.1/1000) were followed by in the order of favorite choice of contraceptive (KIPH, Family planning evaluation report, 1984; KIPH Family plan Service Statistics, 1981-1984). In present paper the present status and knowledge of contraceptives will be summarized.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.6
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• pp.233-241
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• 2005

The present model of a SF6 arc accounts for the copper vapour contamination from the electrodes inside a Laval nozzle of a circuit breaker. Steady state simulations have been done for the arc with electrode gap of 60mm and DC electric current of 500A, 1000A and 1500A for both cases with and without copper contamination. The effects of electrode polarity are considered for the arc current of 1000A. It was found out that evaporation of copper from the anode results in a cooling of the arc in a region close to the electrodes. The electrical potential across the electrodes is not sensitive to the presence of copper vapour, typically less than $4\%$ difference. Transient analysis has been done in order to obtain the arc properties at current zero. The arc current is increased linearly from -1000 to 0A when the upstream electrode is cathode with constant dI/dt of $27.0A/{\mu}s$ (or decreased linearly from 1000 to 0A when upstream electrode is anode). It has been predicted that the presence of copper vapour reduces the interruption capability of the breaker.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.8
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• pp.1188-1195
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• 2022

The 6-port phase correlator consists of one in-phase power divider and three 3-dB 90-degree phase difference power dividers, and is mainly used in a demodulation circuit that determines the phase of an input signal. This paper proposes the wideband 6-port phase correlator that consists of an in-phase power divider using a wideband 2:1 impedance transformer with three 37.5-Ω coaxial cables, and a 3-dB 90-degree phase difference power divide using Wireline. The proposed wideband phase correlator fabricated at a center frequency of 1000MHz has the value of the input reflection coefficient(S₁₁ and S₂₂) -14dB or less in the frequency range of 640~1270MHz. Also, the signal transmission characteristic(S_i1), from the in-phase power divider input port to four output ports, has the amplitude of -6.5±0.6dB and the phase error of within ±3.4°, and the signal transmission characteristic(S_i2), from the 90 degree phase difference power divider input port to four output ports, has the amplitude of -6.1±0.6dB and the phase error of within ±6.2°.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.999-1000
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.999-1000
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• 2010

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.28.4-29
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• 2011

Solar Proton Events (SPEs, ${\geq}\;10\;cm^{-1}s^{-1}sr^{-1}$ with >10 MeV) are very important for space weather forecasting. It is well known that they are associated with solar flares and/or CME-driven shocks. Especially, the CME-driven shocks have been observed as solar and interplanetary type II bursts. In this study, we estimated the occurrence probability of SPEs depending on three groups: (1) metric, (2) decameter-hectometric (D-H), and (3) meter-to-kilometric (m-to-km) type II bursts. For this work, we used SPEs and all available type II burst data in 1996-2004. The primary findings of this study are as follows. First, the majority (77%) of the m-to-km type II bursts are associated with SPEs and its probability is noticeably higher than D-H type II bursts probability strongly depend on longitude: eastern (0%), center(45%), and western (33%) for X-class associated metric type II bursts, eastern (15%), center (55%), and western (50%) for X-class associated D-H type II bursts, eastern (17%), center (77%), and western (64%) for X-class associated m-to-km type II bursts. Third, for m-to-km type II bursts, the SPE probability increases with CME speed: 400km/s${\leq}$V <1000km/s (36%), 1000km/s ${\leq}$V<1500km/s (40%), 1500km/s${\leq}$V (66%). Finally, we expect that these results will be used for setting up more reasonable solar proton event forecasting models.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.1
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• pp.37-42
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• 2016

In this study, we examined the burning rate of the uncured propellant (with and without a curing agent application) in order to inspect the process of the HTPB solid propellant. The burning rate of the uncured propellant, that did not contain the curing agent, was approximately 9.7 mm/s at 1000 psi. In relation to the curing time, the burning rate was constant. The propellant, with the curing agent application, was approximately 8.1 mm/s showed a tendency of slowing as it burned. When the cure reaction rate was low, in accordance to the time, there were small changes in burn rate. However, when the cure reaction rate was high, the difference in burning rate was increased. The burning rate of a fully-cured propellant was approximately 6.8 mm/s, which appeared to be the lowest in order.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.2
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• pp.77-84
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• 1989

Twenty-four Hereford steers, 22 months old and a mean liveweight (${\pm}\;s.e.$) of $250\;{\pm}\;7\;kg$ were used in an experiment to evaluate over 42 days two rates of copra meal supplementation to cattle on a low N ($8.6\;{\pm}\;0.9$ g N/kg dry matter (DM)), low digestible ($45\;{\pm}\;5.2%$ DM) native pasture hay. Steers given the two rates (500, 1000 g/steer/day; i.e. 500C, 1000C) were compared to steers on a non-supplemental diet and to the effects on steers of supplemental urea (30g/steer/day; 30U) or with copra meal (500 g/steer/day; 500C.U), or of cottonseed meal (500 g/steer/day; 500S). Liveweight change was increased (P<0.01) by all of the supplements except by supplemental urea. The most effective treatment, 1000C, increased significantly (P<0.01) liveweight change (946 g/day) in steers above all supplements except those steers given 500C.U (718 g/day). Hay intake per unit liveweight was increased (P<0.05) by 7% by the 30U and 500C.U treatment, and by 9% by 500C; this group having the highest supplements, being greatest (P<0.05) for the 1000C group (6.0 g feed intake/g gain) and least for the 500S supplemented group (11.5 g/g gain). Efficiency was lowest (18.6 g/g gain) for the non-supplemented steers on the basal hay diet. Copra meal N was less degradable (i.e. 29%) in nylon bags over 15 hours in the rumen than was cottonseed meal N (37%), and rumen ammonia concentrations were lower (P<0.05) in cattle supplemented with copra meal (25, 27 mg N/L) than in cattle given urea (36 mg N/L) or cottonseed meal (39 mg N/L). It is concluded that copra meal at a daily rate of 500 g/head, and with rumen soluble nitrogen from urea, is an effective supplement for improving growth of cattle on a low quality forage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.1000-1009
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• 2013

This study investigated changes in behavioral performance before and after watching a multi-view 3D content by using auditory stimuli based on the selective attention theory in order to quantitatively evaluate 3D visual fatigue. Twenty-one undergraduates were asked to report on their current visual and physical condition both in the pre- and post-experiment. A selective attention task was conducted before and after mobile 3D viewing to compare the changes in performance. After performing a Wilcoxon's matched-pairs signed-ranks test on the subjective ratings of 3D visual fatigue, participants were categorized into two groups, unfatigued and fatigued group with a definite criterion. For the unfatigued group, no significant fatigue effects were found in behavioral response times and accuracies to specific auditory targets. In sharply contrast to the unfatigued group, the fatigued group showed significantly delayed response times and less response accuracies. However, no significant changes in accuracies for a working memory task were observed in both groups.

• Journal of Preventive Medicine and Public Health
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• v.29 no.3 s.54
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• pp.539-553
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• 1996

The study was conducted from May to September in 1994 to investigate applicability of the Hearing Handicap Inventory for the Elderly-Screening version(HHIE-S) in parallel with the pure-tone audiometer to the initial screening test of noise-induced hearing loss(NIHL) in some noise-exposed workers. Subjects were selected by systemic sampling that took every 10th person from 6, 700 workers taking the annual occupational health examination by the department of Health Maintenance of Dongsan Hospital Keimyung University in Taegu. The authors administered the pure-tone audiometric test and self-reported questionnaire of HHIE-S including items of sociodemographic and job-related variables concurrently. The final subjects analysed were 1,019(488 males and 531 females) excluding fourteen persons who had many missing values in their questionnaires. The reliability coefficients of HHIE-S scale by Cronbach's alpha were 0.84. In the univariate analysis of hearing handicap measured by the HHIE-S, work duration, military service and the hearing threshold loss at 1KHz and 4KHz by the initial audiometer were significant in males while age, work duration and hearing threshold loss at 1KHz and 4KHz were significant in females. In the stepwise linear regression analysis, hearing threshold loss at 1KHz and 4KHz, was the only selected variable explaining the hearing handicap in males and hearing threshold loss at 1KHz and 4KHz, age, and work duration were selected in females. In ROC curves for HHIE-S scores against NIHL as gold standard which was defined by the follow-up audiogram as more than 30dB of the average of 0.5/1/2KHz and 50dB at 4KHz, the optimal cutoff for the parallel HHIE-S appeared to be 8. The results suggest that HHIE-S appeared to have some reliability and validity in this data and might be used in screening NIHL in parallel with pure-tone audiometer in noise-exposed workers.