• 산업경영시스템학회지
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• 제38권1호
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• pp.21-29
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• 2015

A steady-state controllable M/G/1 queueing model operating under the {T:Min(T,N)} policy is considered where the {T:Min(T,N)} policy is defined as the next busy period will be initiated either after T time units elapsed from the end of the previous busy period if at least one customer arrives at the system during that time period, or after T time units elapsed without a customer' arrival, the time instant when Nth customer arrives at the system or T time units elapsed with at least one customer arrives at the system whichever comes first. After deriving the necessary system characteristics including the expected number of customers in the system, the expected length of busy period and so on, the total expected cost function per unit time for the system operation is constructed to determine the optimal operating policy. To do so, the cost elements associated with such system characteristics including the customers' waiting cost in the system and the server's removal and activating cost are defined. Then, procedures to determine the optimal values of the decision variables included in the operating policy are provided based on minimizing the total expected cost function per unit time to operate the queueing system under considerations.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.25-28
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• 2007

In this study we measured the changes according to time respectively on the basis of 0, 30, 60 and 90 minutes, taking into consideration the decline in fluidity of concrete according to elapsed time to analyze manufacturing capability of batcher plant according to elapsed time of ready-mixed concrete manufactured in batcher plant, and offer basic data for mixture design of ultra-high strength concrete. The proportion of water-binder was 23.55, water content was 160kg/m3, proportion of replacement of crushed sand was 0, 20 and 40% at 3 level, and we applied to the same condition of triaxial component using blast furnace slag powder and silica fume as admixture. And to meet the demand of certain fluidity, we measured respectively on property before and after hardening of ultra-high strength concrete using superplasticizer. As a result of experiment, before hardening of ultra-high strength concrete showed the best fluidity in conditions of crushed sand replacement rates of 20% and superplasticizer composition of 1.95%, but it appeared that fluidity drops as time goes by in the same composition condition. And it appeared that when it comes to hardened, the changes of compression strength according to elapsed time by crushed sand replacement rates were within 1MPa. Therefore, it turned out that the difference of strength according to elapsed time was low and compression strength of 280dys in composition mentioned above appeared highly as 88MPa.

• 한국산학기술학회논문지
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• 제7권3호
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• pp.314-318
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• 2006

본 연구에서는 점 용접된 박판이 파괴되어 가는 동적 과정을 시뮬레이션 함으로서 그 점용접부의 강도를 해석하는데 있다. 위판이 아래의 판에 대하여 늘어난 후 0.64 ms가 경과된 시점에서 서로 점 용접된 위판 및 아래 판이 떨어져 나감을 알 수 있다. 비교적 위판 및 아래 판 가운데의 용접 부위에서 최대의 von Mises 응력을 나타내고 있다. 용접이 깨어지는 시점인 0.64 ms 부근에서는 그 내부에너지가 상당히 감소되고 운동에너지는 급격히 증가됨을 알 수 있다. 미끄럼 에너지는 시간이 경과됨에 따라 계단형으로 감소되어 경과 시간이 0.2 ms 부근에서 0이 되다가 그 후로는 미끄럼 에너지가 음수의 값이 되어 두 판들은 오히려 고착이 되는 것을 알 수 있다.

• 한국환경복원기술학회지
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• 제3권2호
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• pp.47-52
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• 2000

This study was carried out to analyze the effects of elapsed years and physical properties on fill-slope alignment of forest road. For the study, 21 forest roads in Puy$\check{o}$-gun and Asan-shi of Chungchungnam-do were selected and fifteen factors that might influence on fill-slope alignment were analyzed. The major forms of alignment of the fill-slope in the time of construction were concave and compound. But, with the elapsed years, the concave and compound forms have decreased and linear and convex forms have increased. And fill-slope alignment was strongly related with fill-slope distance, fill-slope gradient and ground gradient among the physical properties.

• 한국조리학회지
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• 제8권3호
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• pp.259-265
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• 2002

In this study, various kind of onion herb kimchi differing in herb contents were prepared. Sensory evaluation indicated that rosemary was best of all for the tested herbs. By the sensory analysis, it seemed that 0.5% addition of fresh herb powder for onion kimchi was most preferable and 2% addition was not acceptable. Hot spice of onion was remained when kimchi was prepared but it disappeared as storage time elapsed. According to texture analysis, hardness decreased as storage time elapsed for onion kimchi without herb, but the degree was mitigated for onion herb kimchi.

• 한국패류학회지
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• 제19권1호
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• pp.71-79
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• 2003

두족류는 흡반에 의한 흡착력이 강하여 방류시 분리 포획에 어려움이 있는 어린 주꾸미의 마취 소요시간에 따른 효과면에서 200 ppm 이하의 농도에서 염산리도카인이 MS-222보다 1.6-4.5배정도 마취가 빨랐고 300-500 ppm의 농도에서는 5.10-6.0배 빨랐다. 노출시간에 따른 마취율과 회복률에 염산리도카인이 MS-222보다 저농도에서 짧은 시간 내 마취되고 고농도에서 빠른 시간 내에 회복되었다. 1차 마취 후 경과시간별 염산리도카인의 재마취에서 농도가 낮고 경과시간이 길수록 마취개시 및 종료시간이 늦어지고 농도가 높고 경과시간이 짧을수록 마취개시 및 종료시간이 빨라졌다. 재마취 회복 또한 저농도에서 경과시간이 길수록 빠르고 고농도에서 경과시간이 짧을 수록 회복이 늦어졌다. 주꾸미의 경우 MS-222보다는 염산리도카인이 마취에 좋았으며 작업을 고려한 사용농도 및 한계시간은 100 ppm 농도에 15분 이내가 적당하였다.

• Journal of Oral Medicine and Pain
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• 제12권1호
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• pp.27-40
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• 1987

When the men die, uniform changes progress. Many investigators have studied about the time after death, but it's very difficult to measure the time elapsed since death, particularly in highly decomposed or probably skeletonized bodies. But the teeth are very stable to the changes of physical and chemical properties and their changes are very slow. At this point of view, the author studied this theme as one of the pioneers in our country. In this study, the author observed the degree of the dentinal expansion and the crack of enamel and cementum of the teeth which had been extracted from December, 1983 to September, 1987. The teeth were extracted from the male and female who was 18 to 85 year old. The results are followed; 1. The degree of dentinal expansion increased rapidly until 7 months with high degree and then decreased slowly. 2. The equation of regression for representing x as the degree of the dentinal expansion and y as the time elapsed since death, is y = 29.43-1.13x (p<0.05) 3. The crack of the enamel surface seemed to begin at 1 year from extraction and to increase apparently before or after 20 months. 4. The crack of the cementum began at 3 months from extraction and dendrite crack began at 16 months from extraction. After this, the crack increase continuously and the rate of cracking were more rapid as compared with that of enamel. 5. It seems to be useful to measure the time elapsed since death using the degree of dentinal expansion and the crack of enamel and cementum, particularly in the old bodies after death.

• 한국운동역학회지
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• 제27권1호
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• pp.75-81
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• 2017

Objective: The purpose of this study was to compare and analyze the kinematic variables and electromyography (EMG) findings that change with varying characteristics of crouch start and feedback provision, and to provide the fundamental data for record improvement in 400 mH. Method: Four short-distance runners participated in the experiment. The analyzed variables were elapsed time per interval, stride length, and muscle activities in three lower limb muscles. These variables were analyzed by using Kwon3d XP and Noraxon Myoresearch. The participants were subjected to three conditions, including two conditions that relate to the thrusting foot on the rear block and another condition pertinent to feedback provision. Results: In terms of a one-step interval, the elapsed time in condition A was longer than that in condition B, and the one after the feedback was the longest. The stride length of a one-step interval was the longest in condition A. The stride length of a two-step interval was the shortest in condition A. The muscle activity during a one-step interval showed differences in vastus medialis and medial gastrocnemius, with condition A being the highest. Conclusion: When the non-dominant left foot was located at the back, negative results were observed in terms of elapsed time and stride length. Moreover, an imbalance in muscle activity was observed between the left and right feet when the left foot was placed at the back. As a result, significant differences in elapsed time, stride length, and muscle activity were observed depending on the foot placed on the rear block. In conclusion, we identified the characteristics of crouch start in 400 mH, and a specialized program must be suggested.

• 한국농공학회지
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• 제30권4호
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• pp.85-93
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• 1988

This laboratory study was carried out in order to produce fundamental data for analyzing salt movement and desalinization effects, using samples of silt loam soil collected in Gyehwado and Daeho reclaimed tidelans, and samples of silty clay loam soil collected in Kimie tideland. Desalinization experiments with gypsum treatment were performed to analyze changes of the hydraulicc conductivity with changes of the soil property and the salt concentration during the desalinization of reclaimed tideland soils by leaching through the subsufface drainage, and correlations between factors infl uencing the reclamation of salt affected soils were analyzed by the statistical method. The results were summarized as follows: 1. The reclaimed tideland soils used in this study were saline-sodic soils with the high exchangeable sodium percentage and the high electrical conductivity. 2. Changes of the hydraulic conductivity with the amount of leaching water and the leaching time elapsed were affected by the amount of gypsum except exchangeable sodium and clay contents. The regression equation between the depth of water leached per unit depth of soil (Dw / Ds : X) or the square root of the leaching time elapsed (T $^1$ $^2$ : X) and the relative hydraulic conductivity (HCr:Y) could be expressed in Y=a . bx. 3. The more exchangeable sodium and clay contents regardless of the amount of gypsum, the more the leaching time was required until a given volume of water was leached through the soil profile. The regression analysis showed that the relationship between the depth of water leached per unit depth of soil(Dw /Ds:X) and the square root of the leaching time elapsed(T$^1$$^2$ :Y) could be described by Y=a . Xb. 4. The hydraulic conductivity was influenced to a major degree by the salt concentration provided that the electrical conductivity was below 10 mmhos / cm during the desalinization of reclaimed tideland soils. The regression equation between the relative electrical conductivity ( ECr : X) and the relative hydraulic conductivity (HCr:Y) could be expressed in Y=a + b . X-$^1$. 5. In conclusion, the hydraulic conductivity, leaching requirements and the leaching time elapsed can be estimated when the salt concentration decreases to a certain level during the desalinization of reclaimed tidelands, and the results may be applied to the analysis of salt movement and desalinization effects.

• 항공우주기술
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• 제8권2호
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• pp.92-97
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• 2009

인공위성 반작용휠의 속도측정은 크게 펄스 개수 측정 방법과 펄스 간 시간 측정 방법으로 나뉠 수 있다. 본 연구에서는 반작용휠의 타코 펄스에 불균일성이 존재할 때 두 가지 방법들에 대한 오차 분석이 이루어졌다. 펄스 간 시간 측정 방법은 고속에서는 시간 측정에 사용되는 고주파 클럭에, 저속에서는 시간 측정에 사용되는 펄스 개수에 크게 영향을 받지만 이 값들을 잘 선택함으로써 분해능 및 정밀도가 펄스개수 측정 방법보다 항상 더 좋도록 설계할 수 있다. 그러나 반작용휠의 타코 펄스 간격에 불균일성이 존재할 때에는 측정 정확도가 저하된다. 본 연구에서 저하되는 측정 정확도를 정량적으로 분석하였으며 그 결과 시간 측정에 사용되는 펄스 개수를 늘림으로써 저하 되는 성능을 향상시킬 수 있음을 해석적으로 검증하였다.