• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.22 no.2
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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.

• The Journal of Korean Obstetrics and Gynecology
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• v.24 no.3
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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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• v.18 no.1
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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.

• The Research Journal of the Costume Culture
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• v.22 no.4
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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.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.4
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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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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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.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.256-262
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• 2014

Cycle length of domestic nuclear power plants is determined by the demand-supply plan of utility company. The target cycle length is achieved by adjusting the number of feed fuel assembly and fuel enrichment. Traditionally, utility company first select the number of feed fuel assembly and then find out the fuel enrichment to achieve the special cycle length. But it is difficult to find out if this method is most economical than any other combinations of the enrichment and batch size satisfying the same cycle length. In this paper, core depletion calculation is performed to find out the optimum combination of the enrichment and batch size for given target cycle length in terms of fuel cycle cost using commercial core design code; CASMO/MASTER code. To minimize the uncertainty resulting from transition core analysis, levelized fuel cycle cost analysis was applied to the equilibrium cycle core in order to determine the optimum combination. The sensitivity study of discount rate was also carried out to analyze the levelized fuel cycle cost applicable to countries with different discount rates. From the levelized fuel cycle cost analysis results, the combination with smaller batch size and higher fuel enrichment becomes more economical as the discount rate becomes lower. On the other hand, the combination with higher batch size and lower fuel enrichment becomes more economical as the discount rate becomes higher.

• Journal of the Korean Professional Engineers Association
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• v.34 no.2
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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.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.1
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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.

• Journal of Korean Physical Therapy Science
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• v.18 no.3
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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.