• 방사성폐기물학회지
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• 제22권2호
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• pp.219-226
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• 2024

Democratic People's Republic of Korea (DPRK) has produced weapon-grade plutonium in a graphite-moderated experimental reactor at the Yongbyon nuclear facilities. The amount of plutonium produced can be estimated using the Graphite Isotope Ratio Method (GIRM), even without considering specific operational histories. However, the result depends to some degree on the operational cycle length. Moreover, an optimal cycle length can maximize the number of nuclear weapons made from the plutonium produced. For conservatism, it should be assumed that the target reactor was operated with an optimal cycle length. This study investigated the optimal cycle length using which the Calder Hall MAGNOX reactor can achieve the maximum annual production of nuclear weapons. The results show that lower enrichment fuel produced a greater number of critical plutonium spheres with a shorter optimal cycle length. Specifically, depleted uranium (0.69wt%) produced 5.561 critical plutonium spheres annually with optimal cycle lengths of 251 effective full power days. This research is crucial for understanding DPRK's potential for nuclear weapon production and highlights the importance of reactor operational strategy in maximizing the production of weapons-grade plutonium in MAGNOX reactors.

• 대한한방부인과학회지
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• 제24권3호
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• pp.73-84
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• 2011

Objectives: This study examined the recent update of factors affect length and regularity of menstrual cycle and symptoms need for diagnosis in oriental medicine. Methods: For factors, we searched the key word "menstrual cycle length and factor" in ScienceDirect(http://www.sciencedirect.com) and we mainly searched symptoms in the journal of oriental obstetrics & gynecology and text. Results: The result are shown in the Table 1-3. Conclusion: In fact as the fluctuation of menstrual cycle length and regularity is very high in healthy women, we must observe the factor affect menstrual cycle with attention even though rule out disease, operation and HRT etc. these researches show potential to compound oriental medicine care and factor of menstrual cycle change.

• Journal of Chest Surgery
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• 제18권1호
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• pp.1-6
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• 1985

Isolated sinus node cells of the rabbit were used to assess the effects of extracellular Na, K, Ca and Mg concentrations on cardiac pacemaker activity. With intracellular glass micro-electrodes spontaneous action potentials of SA node were recorded and the effects of various ions and their blockers were analyzed in terms of the cycle length, the amplitude and the duration of action potentials, the results obtained were as follows. 1. Sodium reduction [up to 30%] decreased the amplitude of action potential and lengthened the cycle length. TTX, specific blocker of Na channel slightly lengthened the cycle length. 2. Increasing potassium ion concentration, the duration of action potential decreased and the frequency increased in 6mM, however, spontaneous action potential was stopped in 24 mM. Barium ion known to be decreasing K conductance increased the duration of action potential but no significant change in the cycle length was noticed. 3. Calcium ion has shortening effect on the duration and the cycle length of action potential but not with dose-dependent manner. Cadmium ion .[0.02mM] lengthened cycle length and the duration of action potential. 4. Increasing the concentration of magnesium ion the cycle length was lengthened, significantly.

• 복식문화연구
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• 제22권4호
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• pp.543-554
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• 2014

The purpose of this study was to find whether hemline cycles exist and whether hemlines show greater within-year variability over time. Utilizing US Vogue data from 1950 to 2013 on hemline length of women's daywear, total 2102 day-dresses or skirts on full fashion pictures were analyzed. The skirt length was divided by the total length of figure in the picture which was measured from shoulder to ankle. Aggregated yearly means smoothed by means of three-point moving averages were used to provide a better indication of the long-term direction of movement of the hemline. Within-year hemline variability was smoothed by the way of three-point moving average as well. The data showed five cycles on hemline change processes. The first cycle took 21 years from 1950 to 1971, which was the longest period and had the biggest hemline changes. The second cycle was the shortest from 1971 to 1977, in which hemline moved between below-knee length and midcalf. The hemline in the third cycle moved between midcalf and miniskirt. The third cycle took 16 years from 1977 to 1993. The forth was a short cycle from 1998 to 2001, and hemlines moved moderately between below-knee length and above-knee length. The fifth cycle has been on going since 2001, and the hemline has been getting longer after 2007. The within-year variability of hemlines was bigger in 1980s than previous years and was steadily increased.

• 한국의류학회지
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• 제38권4호
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• pp.584-597
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• 2014

This study verified the 'Hemline Index' theory by George (1926) and established a new fashion theory frame to forecast future fashion cycles of skirts by analyzing the past fashion cycle of skirts through a diachronic method. Skirt pictures from 1980-2013 (the post-industrialized period of Korea) were analyzed and representative skirt styles, the fashion cycle of skirts and relation between skirt style, length, width and stock index were identified. A total of 1496 pictures in fashion magazine published over 34 years were selected and analyzed using PASW 18.0. The results were: For 34 years, representative skirts styles were mini skirt, midi skirt and long skirt. Fashion trend cycles of skirt length decreased for 10 years and the fashion cycle showed a trend to shorten. Skirt length & stock index related negatively and skirt length & skirt width related positively. All relations revealed significant results. Finally, the 'Hemline Index' theory of George (1926) was verified. Fashion marketers can develop successful and suitable products using a fashion cycle theory based on the results of this study.

• 설비공학논문집
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• 제24권2호
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• pp.147-154
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• 2012

Recently, many researchers have studied the performance of the transcritical $CO_2$ refrigeration cycle in order to improve the system efficiency. In this study, the length of IHX in the $CO_2$ ejector cycle was varied so as to evaluate the performance improvement. As a result, compressor work and cooling capacity was increased by 3% and 5% as the length of internal heat exchanger was changed from 3 m to 15 m. The best COP was appeared at internal heat exchanger length of 12 m, and it was 3.01. Besides, the length of internal heat exchanger has a big effect to pressure lift ratio and entrainment ratio in the ejector $CO_2$ cycle and it may be changed with operating conditions and system specifications.

• 에너지공학
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• 제23권4호
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• pp.256-262
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• 2014

국내 원자력발전소의 주기길이는 전력회사의 전력수급계획에 따라 결정된다. 주기길이는 노심에 장전할 신연료 다발수와 핵연료 농축도를 조정하여 결정할 수 있다. 전력회사에서는 특정 주기길이를 만족시키기 위한 방법으로 신연료 다발수를 정한 후 핵연료 농축도를 결정하는 방법을 적용하고 있다. 그러나 이 방법의 경우 같은 주기길이를 갖는 다른 신연료 다발수와 핵연료 농축도의 조합들 보다 핵연료 주기비 측면에서 가장 경제적인지 판단할 수가 없다. 따라서 본 분석에서는 상용 노심설계 코드인 CASMO/MASTER 코드를 사용하여 OPR1000(Optimized Power Reactor 1000) 발전소를 대상으로 신연료 다발수와 핵연료 농축도 조합에 대한 노심 연소계산을 수행하여 동일한 주기길이를 갖는 최적의 신연료 다발수와 핵연료 농축도 조합은 무엇인지 분석하였다. 천이노심계산에서 발생할 수 있는 불확실도를 최소화하기 위해 노심 특성인자들이 변하지 않는 평형노심(equilibrium cycle)까지 계산을 수행하여 이때의 계산결과를 핵연료 주기비 계산에 사용하였다. 또한 평준화 핵연료 주기비(levelized fuel cycle cost) 계산에 있어 중요한 인자인 할인율(discount rate)에 대해서 국내뿐만 아니라 다른 나라의 실정에도 적용 가능하도록 민감도 분석을 수행하였다. 평준화 핵연료 주기비(levelized fuel cycle cost) 평가 결과 할인율(discount rate)이 낮은 경우 신연료 다발수는 줄이고 대신 핵연료 농축도를 높이는 조합을 통해 특정 주기길이를 만족시키는 방법이 경제적인 것으로 나타났다. 반면 할인율(discount rate)이 높은 경우는 핵연료 농축도는 낮추고 신연료 다발수를 늘리는 조합을 통해 특정 주기길이를 만족시키는 방법이 경제적인 것으로 나타났다.

• 기술사
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• 제34권2호
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• pp.31-36
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• 2001

The Otto Cycle of conventional gasoline engine has no difference between compression ratio and expension ratio. because of the same length of 4 strokes : Intake, compression, expension, exhaust. On the other hand, miller cycle engine achieves both low-compression ratio and high-compression ratio by shortening the length of compression stroke among 4 strokes. Therefore miller cycle engine is essential for lessening knocking and improving heat efficiency. This paper Is designed to discribe not only principle and the development trend of miller cycle engine but also the control system and the technical characteristics of it.

• 대한산업공학회지
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• 제19권1호
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• pp.73-77
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• 1993

This paper considers an Economic Order Quantity Model under random life cycle. It is assumed that the life cycle of the product is unknown; a random variable. Three cost parameters are considered; ordering cost, inventory carrying cost and salvage cost. Expected total cost is the optimization criterion. We show that the optimal cycle length is unique and finite, and present a simple line search method to find an optimal cycle length.

• 대한물리치료과학회지
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• 제18권3호
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• pp.33-39
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• 2011

Background : The purpose of this study was to apply cervical orthosis for temporal parameters of gait was to evaluate the effect. Methods : Seven normal adults participated in this study. Before and after applying a cervical orthosis compared to gait. Outcome measure were: general characteristics, temporal parameters of gait. General chacteristics included age, gender, height, weight. Temporal parameters included the Velocity cycle, Stride length, Step length, Cadence cycle, Initial double support time. Temporal parameters of gait, using the motion analysis system for cervical orthosis were evaluated before and after applying. The data was analyzed using SPSS 12.0 software and the Wilcoxon's signed-ranks test. Results : Velocity cycle and Step length were no significant differences(p>0.05). But Stride length, Cadence cycle, Initial double support time were significant(p<0.05). After apply Cervical orthosis in gait, Stride length and Initial double support time was decreased and Cadence cycle was increased. Conclusion : Changes in temporal of temporal parameters of gait was apply a cervical orthosis with the limitations of vision due to take effect. Therefore, Cervical orthosis does not interfere with the normal gait pattern by limiting the Range of Motion so that we consider to apply.