Modern automated manufacturing processes employ automated guided vehicles(AGVs) for material handling, which serve several machining centers(MCs) in a factory. Optimal scheduling of AGVs can significantly help to increase the efficiency of the manufacturing process by minimizing the idle time of MCs waiting for the raw materials. In this paper, we will analyse the requirements for an optimal schedule and then provide a mathematical framework for an efficient schedule of material delivery by an AGV. With this model, the optimal number of MCs to be utilized will also be determined. Finally, the material delivery schedule employing multiple journeys to the MCs by the AGV will be carried out. Through rigorous analysis and simulation experiments, we shall show that such a delivery strategy will optimize the overall performance.

Manufacturing companies must possess a new type of production system with characteristics of reconfigurability, reusability and scalability (Dove 1995), i.e. an agile manufacturing system. Such system will allow flexibility not only in producing a variety of part, but also in changing the system itself, which is a difference form flexible manufacturing systems. A fundamental early step in the reconfiguring process for agile manufacturing system is to develop a model that adequately describes the proposed systems, in order to be able to study and evaluate the impact of the reconfiguring decision on the system performance, before its construction. Therefore, in this paper, an Object & Knowledge-based Interval Timed Petri-Net (OKITPN) approach is proposed.

이동하중에 의한 교량의 공진현상은 차량의 속도와 유효타격간격에 의해 결정되는 이동하중의 운행진동수와 교량의 고유진동수가 일치할 경우 발생하게 된다. 철도교의 경우에는 정해진 열차만 통행하게 되므로 이러한 유효타격간격이 정량적으로 정해져있다 본 연구에서는 고속전철하중을 받는 교량의 지간장 변화에 따른 교량의 공진현상과 공진소멸현상을 분석하고자 한다. 강합성형 철도교에 대하여 판요소와 공간뼈대요소의 조합에 의한 3차원 모델링을 적용하였으며 또한 고속전철하중은 이동집중하중 모델과 3차원 모델링 두가지 방법을 사용하였다 수치예제로서 지간장 변화에 따른 수직처짐의 동적확대계수 상판의 최대수직가속도 단부회전각 등의 동적응답 분석을 통하여 고속철도 교량의 동적안정성에 적합한 지간장 설계기준에 대하여 논의 하였다.

As the pipe houses were constructed by imitation and routine without a structural design by now, they were often destructed by a strong wind or a heavy snowfall. The purpose of this study was to provide the basic data for the safety structural design of the pipe houses in Kyungpook region to prevent meteorological disaster. It was shown that the change of frame interval according to the safety factor under the wind load was similar that under the snow load. But the safety frame interval under the snow load was approximately 0.5-0.6m greater than that under the wind load for equal safety factor. Therefore, it seemed that the maximum safety frame interval was to be decided by the snow load. The frame of the pipe houses in Seungju region was structurally stable under the design snow load in recurrence intervals of 8-15years, but was unstable in Kolyong region.

항로는 선박의 통항이 빈번하고 특히, 항로의 입구부는 선박의 출입이 잦아 사고의 위험이 높은 지역이지만, 항로 단면에서의 통항 분포에만 초점을 맞춘 연구가 다수였으며, 항로 통항 선박간의 시간분포에 대한 연구는 부족하였다. 이에 본 연구에서는 대상항로에서의 통항 선박간의 시간 최적분포를 분석하기 위해서 1주일간의 선박의 통항현황을 조사하였다. 통항현황을 바탕으로 항로 입구부에 1개의 Gate line을 선정하고, Gate line을 통과하는 선박을 입출항, 교통량으로 구분하여 분석하였다. 대상항로의 해상교통 분석 자료를 바탕으로 입출항과 교통량으로 구분하여 항로 통항 선박간의 시간 최적 확률분포를 분석하였다. 최적 확률분포를 분석하기 위하여 경계분포, 비경계분포, 비음수분포, 고급분포로 구분하여 총 31개의 확률분포를 적용하였으며, 최적 확률분포 상위 3개를 분석하기 위하여 KS 검정을 사용하였다. 분석 결과 대상 항로에서 통항 선박간의 최적 시간 확률분포는 Wakeby 분포로 분석되었으며, 도로교통 등의 선행연구에서 사용한 비음수 분포와 다르게 고 급분포가 대부분을 차지하는 것으로 분석되었다. 따라서 향후 항로 통항 선박간의 시간 분포를 적용함에 있어 다른 교통 분야의 선행연구에서 사용한 대표적인 확률분포를 적용하는 것은 적합하지 않는 것으로 판단된다. 또한 실제 교통조사 시 통항 선박간의 거리와 최적 확률분포로 추정한 거리가 비교적 유사함을 확인하였다. 다만 본 연구는 대표적인 1개의 항로를 분석한 만큼 향후 다양한 항로에서의 통항 선박간의 시간 간격 및 교통용량 산정 등의 후속연구가 필요한 것으로 판단된다.

In this study, using coke dust from ironwork, the pulse pressure on a pulse air jet bag filter was investigated considering the influence of the pressure loss due to filtration velocity and pressure intervals. The research on the optimal pulse pressure prediction of a pulse air jet type bag filter using coke dust showed the following results. Pressure loss volatility produced by the pulse pressure under low dust concentration(0.5, 1 g/m3) and low face velocity(1.25 m/min) was less than 10 mmH2O. This suggests that the pulse pressure has a low impact on the pressure loss. In contrast, pressure loss volatility under high dust concentration(3 g/m3) and high face velocity(1.75 m/min) was 25 mmH2O. Therefore, pulse pressure with high dust concentration and high face velocity has a strong influence on the pressure loss volatility, compared to the condition of low dust concentration and low face velocity. The optimal pulse pressure of inlet dust concentration(0.5 g/m3) was 6 kg/cm2 under the same face velocity(1.75 m/min). As concentration increased from 1 to 2 g/m3, the pulse pressure gradually reached 5 kg/cm2 thus indicating that the pulse pressure(5 kg/cm2) is pertinent at a high concentration(3 g/m3). The pulse intervals: 20, 25 and 30 sec, which are relatively longer than 10 and 15 sec, corresponded to high pressure loss volatility produced by the pulse pressure. Furthermore, low pressure loss volatility was noted at 5 kg/cm2 of the overall pulse pressure.

Recently, the evaluation of the grout chamber of PC bridges has been emphasized in order to prevent many problems in advance. This paper analyzes the electrical resistance of the MWCNT cement composites by electrode intervals in order to select the optimum electrode location for evaluation of grout chamber. It is concluded that the electrical resistance of the MWCNT cement composite specimens increase as the electrode interval is longer.

The objective of this study was to determine the mitotic intervals (τ0) of two consecutive cell divisions and synchronous embryonic cleavage in grass puffer, Takifugu niphobles at different water temperatures (18, 20, 22, and 24℃). The color of the fertilized egg was light yellowish. The egg type was demersal and unadhesive. Egg weight was 0.09±0.002 mg. The sizes of unfertilized eggs were smaller than fertilized eggs in major axis and minor axis at 20℃ (p<0.05). The size of the fertilized egg of 18℃ water temperature group at the blastodisc stage was the smallest (p<0.05), but no significant differences were observed in the other water temperatures group except 18℃ water temperature group (p>0.05). The first cleavage stages at 18, 20, 22, and 24℃ were at 75, 90, 105, and 120 mins, respectively. As water temperature was increased, embryonic development and formation time of the first cleavage furrow were accelerated. There were negative correlation between τ0 and water temperature for grass puffer (Y=–1.225X+70.05, R2=0.988, n=10, where Y was τ0 and X was temperature). This study confirmed that successful hatching of grass puffer was related to water temperature. Chromosome manipulation will be helpful for this species using cleavage frequency and τ0.

In the study, direct tensile test was conducted to perform statistical approaches to the maximum tensile strength of design strengths (120, 150 and 180 MPa), and then the direct tensile database construction was made to examine the reliability of the direct tensile test.

We screened the drought tolerant maize using seventeen maize genotypes from different sources, nine inbred genotypes from United States Department of Agriculture (USDA) (B73, CML103, CML228, CML277, CML322, CML69, Ki3, Ki11, and NC350), three Southeast Asian genotypes (DK9955, LVN-4, and 333), and five Korean hybrids (Cheongdaok, Gangdaok, Ilmichal, Kwangpyeongok, and Pyeonganok). We evaluated anthesis-silking interval (ASI), leaf senescence (LS), ears per plant (EPP), tassel length (TL), and fresh weight (FW) at silking date. According to ASI and LS examination, CML103 and Kill were drought tolerant genotypes, wheareas Ki3 and 333 were drought susceptible. EPP, TL, and FW differed according to drought resistance. Grain yield was correlated strongly with ASI, but moderately with LS. Difference in ASI between drought-stressed (DS) and well-watered (WW) conditions was less than three days in CML228, CML103, Cheongdaok, NC350, B73, Ki11, CML322, and Kwangpyeongok, whereas that of Ki3, Pyeonganok, and Gangdaok was more than 6.5 days. We concluded that CML228, CML103, Cheongdaok, NC350, B73, Ki11, CML322, and Kwangpyeongok are drought tolerant genotypes, whereas Ki3, Pyeonganok, and Gangdaok are drought susceptible.

This experiment was carried out to determine the treatment interval on neem product for control of Bemisia tabaci on eggplant using eco-friendly agriculture. We have investigated the control effect of B. tabaci, growth characteristics of eggplant, economics according to neem product treatment interval on eggplant. The longer neem processing interval tended to decrease control effect on nymphs of B. tabaci. Control effect of nymph of B. tabaci according to treatment interval of 3 days, 5 days, 7 days, 10 days, and 15 days were 96.7%, 89.7%, 76.1%, 73.4%, and 51.0%, respectively. This result was the same tendency in adult of B. tabaci control effects on eggplant. Growth characteristics of eggplant according to neem the treatment interval of 3 days, 5 days, and 7 days, was less damaged on of B. tabaci. However, the 10 days, 15 days, and untreated of neem treatment intervals were badly damaged by B. tabaci. Therefore, neem treatment interval of 3~7 days for control of B. tabaci was high control effect. However, it is considered to be the most suitable to process every seven days considering the economics and so on. The results of economic analysis from income of 7 days neem treatment interval was the most high as 19.505 thousand won per 10a and the most economical treatment for control of B. tabaci.

This study was conducted to examine the effects of irrigation interval and fertilizer level on changes in soil chemical properties and growth of cut flower in soil retarding culture of standard chrysanthemum (Dendranthema grandiflorum) ‘Iwanohakusen'. The compound fertilizer (Poly-Feed, N-P-K 19-19-19) diluted with 1 g･L -1 were treated by irrigation intervals of 1 time/1 day (1.5 L･m -2 ), 1 time/2 days (1.5 L･m -2 ), 2 times/3 days (3 L･m -2 ) and 2 times/5 days (3 L･m -2 ). As irrigation interval was long, the nutrient contents of soil decreased. In 1 time/1 day treatment, NO3-N, K, and P2O5 contents of soil decreased, but Ca and Mg contents of soil did not change than before planting. The growth of cut flower, such as stem length, stem diameter, fresh weight, and weight of flower was the best in 1 time/1 day treatment, and was the worst in 2 times/5 days treatment. To examine the proper fertilizer level, the compound fertilizers (Poly-Feed, N-P-K 19-19-19) of 0.2, 0.4, 0.8, and 1.6 kg per 1.5t water were treated 1 time/1 day in 1,000 m 2 field. In fertilizer level of 0.8 or 1.6 kg, EC and nutrient contents of soil were higher or similar than before planting, and inorganic salts in soil were accumulating continuously. The growth of cut flower, such as stem length, number of leaves, weight, and diameter of flower bud was more effective in fertilizer level of 0.4 kg, but it was the worst in excessive fertilizer level of 1.6 kg. Therefore, fertigation of 0.4 kg compound fertilizer with 1 time/1 day in 1,000 m 2 field was the most effective for reasonable soil management and cut flower production of high quality in retarding culture of standard chrysanthemum ‘Iwanohakusen’.

Among agronomists, there appears to be a confusion in selecting among standard deviation (SD), standard error (SE) and confidence interval (CI) in reporting their results as figures and graphs. If there is a confusion in selection among them, there should also be difficulties in interpreting results published in peer-reviewed journals. This review paper aims to help researchers better suited for reporting their results as well as interpreting others by revisiting the definition of SD, SE and CI and explaining in plain words the concepts behind the formula. A variation among observation obtained from an experiment can be explained by the use of SD, a descriptive statistic. If one wants to draw an attention to a variation observed among plant germplasm collected from different regions or countries, SD can be reported along with the mean so that readers can get an idea how much variation exists in the particular set of germplasm. When the purpose of reporting experiment results is about inferring true mean of the population, it is advised to use SE or CI, both inferential statistics. For example, a certain chemical compound is to be quantified from plant materials, estimated mean with SD does not tell the range where the true mean content of the chemical compound would lie. It merely indicates how variable the measured values were from replications. In this case, it would be better to report the mean with SE or CI. The author recommends the use of CI over SE since CI is a sort of adjusted SE. The adjustment comes from t value that considers not only the probability but also n size.

엑스선 의료영상이 디지털 시스템으로 발전함에 따라 의료영상의 평가 방법 또한 디지털 시스템에 맞춰 새롭게 개선되었으며 그 중 MTF(Modulation Transfer Function) 측정법은 Fujita이론에 기초한 에지법으로 ISO에 규정되었다. 에지법의 기초인 Fujita이론은 MTF 측정을 위해 슬릿의 각도를 디지털 검출기의 픽셀 열에 대하여 1° ∼ 2° 기울여 영상을 획득한 후 LSF를 합성하는 것으로 샘플링 간격은 각도에 따라 크게는 1/54배, 작게는 1/28배 감소하게 된다. 본 연구에서 사용된 장비는 Simens사의 MAMMOMAT Inspiration으로 비정질 셀레늄(amorphous selenium) 기반의 0.085 × 0.085 mm2 의 픽셀 사이즈를 갖는 검출기를 이용하여 presampling MTF를 측정하였다. 측정 방법은 Fujita의 슬릿법와 동일한 방법인 와이어법를 이용하였으며 측정된 영상에서 얻은 픽셀값을 이용하여 엑셀에서 이산 푸리에 변환을 시행하였다. 실험 결과 Fujita이론 대비 약 3배 이상의 샘플링 간격(sampling interval)의 경우 해상도 평가 지수인 10% MTF에서 약 85% 이하의 정확도를 보였으며 선예도 평가 지수인 50% MTF에서 약 93% 이하의 정확도를 나타내었다. 하지만 샘플링 간격이 Fujita 이론 대비 2배 정도 늘어난 경우는 50%와 10% MTF 모두 96% 이상의 정확도를 가진다는 것을 알 수 있었다.

We have carried out the bridge inspections according to the laws not considering the characteristics of damages. Also the current condition based inspection cannot consider the rate of bridge deterioration. But it is reasonable to classify the inspection interval according to the risk of each bridge. This suggests the risk based inspection methodology.