In today's business transactions, it is more and more common to see that the buyers are allowed some grace period before they settle the account with the supplier. In this regard, we analyze the problem of determining the buyer's EOQ when the supplier allows day-terms credit. For the analysis, it is assumed that the buyer's demand rate is a function of the on -hand inventory level and the relevant mathematical model is developed.

This paper analyses the tool switching problem in the dynamic environment, where parts to be processed on a flexible machine arrive randomly. As the total number of tools required to Process a set of parts on the machine is generally larger than the available magazine storage capacity, tool switches between parts are usually necessary. We assume that tool switching must be made just before the processing of the parts. Since the time required for tool switches can be significant relative to processing time and cause the processing of parts to be delayed, it is desirable to minimize the number of tool switches. Therefore, we present one heuristic algorithm to minimize the total number of tool switches and the t)reposed heuristic is compared with the KTNS (Keep Tool Needed Soonest) policy on randomly generated problems.

In this study, we describe an analytical process for designing a low Earth orbit constellation for discontinuous regional coverage, to be used for a surveillance and reconnaissance space mission. The objective of this study was to configure a satellite constellation that targeted multiple areas near the Korean Peninsula. The constellation design forms part of a discontinuous regional coverage problem with a minimum revisit time. We first introduced an optimal inclination search algorithm to calculate the orbital inclination that maximizes the geometrical coverage of single or multiple ground targets. The common ground track (CGT) constellation pattern with a repeating period of one nodal day was then used to construct the rest of the orbital elements of the constellation. Combining these results, we present an analytical design process that users can directly apply to their own situation. For Seoul, for example, 39.0° was determined as the optimal orbital inclination, and the maximum and average revisit times were 58.1 min and 27.9 min for a 20-satellite constellation, and 42.5 min and 19.7 min for a 30-satellite CGT constellation, respectively. This study also compares the revisit times of the proposed method with those of a traditional Walker-Delta constellation under three inclination conditions: optimal inclination, restricted inclination by launch trajectories from the Korean Peninsula, and inclination for the sun-synchronous orbit. A comparison showed that the CGT constellation had the shortest revisit times with a non-optimal inclination condition. The results of this analysis can serve as a reference for determining the appropriate constellation pattern for a given inclination condition.

This study was carried out to get the information of Plum tree (192 germplasm) collected in Korea, and to evaluate the organic acid contents and fermentation solution. The organic acid content of fruit was 50.9 ± 6.0 ㎎/g, and which was composed of 55.5% of citric acid, 43.4% of malic acid and 1.1% of oxalic acid, and showed large difference among germplasms. Oxalic acid and malic acid made no differences in organic acid content according to flesh color, whereas citric acid and total organic acid contents were highest in orange color and lowest in whitish green. Malic acid, citric acid and total organic acid contents did not show differences among fruit weight groups, but oxalic acid content was highest at fruit weight of 5.1 ~ 10.0 g and lowest at more than 20.1 g. The sugar content of fermentation solution of fruit was 55.7 ± 1.6 °Brix and the harvest rate was 116.7 ± 8.7%. The correlation coefficients among fruit weight, the sugar content (°Brix) and harvest rate of fermentation solution were very low, and there were correlations of r=–0.551** between fruit weight and oxalic acid, r=– 0.767** between malic acid and citric acid, and r=0.834** between citric acid and total organic acid content.

This study examined the port expansion plan for the fishery port at the east coast of Korea, in accordance with permission conditions for coastal ports such as a limit on the cargo volume and passenger demand for the coastal tourism belt formation. The site was chosen as a municipal coastal port attracting the new ocean industry and building waterfront zone as a hub of new marine tourism. Two different numerical models (Swan and Bouss 2D) were used. Before applying to the target sea area, some numerical tests were conducted for the variation according to Bouss-2D's strong/weak and nonlinear technique compared to the irregular diffraction of semi-infinite breakwater with a theoretical solution. As a result, there was a difference in strong nonlinearity with breaking waves and it was necessary to experiment with a strong nonlinear analysis technique for the actual site. Two numerical models were applied to the fishery port site and the tranquility of some alternatives were analyzed. The numerical results show the most suitable plan was ALT-1, with satisfied harbor tranquility and reasonable economic sense. The extension of the east breakwater and enlarged turning basin of the F-Land plan have brought generally more stable harbor tranquility than the ALT-1. The result can be used as a reference for the port expansion plan in the future.

Background : This experiment was carried out to investigate the occurrence of disease and pest and the yield depending on cultivation methods in Cynanchum wilfordii. Methods and Results : There were damages by anthracnose, aphid, mite, thrips, Gastrophysa atrocyanea, Tropidothorax cruciger and Metcalfa pruinosa. In the case of anthracnose, the number of damaged leaf in the untreated control plot per counting area (67.5 ㎡) was 8.6 times higher than that of chemical treated plot. As a result of investigation of shoot damage and leaf juice damage by Tropidothorax cruciger, which made the most obvious damage symptom, showed the significantly lower degree of damage in the treatments of insecticides (abamectin, suloxac flour liquid wettable powder). In addition to the pest damage, the yield of roots was investigated. As a result, it was found that the yields were 3.8 ㎏, 2.6 ㎏, 1.7 ㎏ and 1.4 ㎏ per 8.5 ㎡ respectively in vine scheme cultivation with chemical control, vine scheme cultivation with non-chemical control, non-vine scheme cultivation with chemical control and non-vine scheme cultivation with non-chemical control. Conclusion : The yield per 1,000 ㎡ was 449 ㎏, which was 1.9 times higher than the national average of three years in vine scheme cultivation with chemical control.

Background : This study was carried out to provide basic data for the cultivation of the rare Glehnia littoralis in Korean Midwest. Methods and Results : In Korean Midwest, Glehnia littoralis was distributed at an average dis tance of 36.1m from the shoreline. The average altitude of the emergence area was 4.2m and the average slope was 4.3%. All the Glehnia littoralis grew on the sand of the coastal sand d unes. The average pH of habitat was 8.4, the organic matter content was 0.4%, and the avail able phosphate content was 9.1 ㎎/㎏. The potassium, calcium, magnesium and sodium of exc hangeable cation were 0.09, 9.31, 0.43 and 0.23 cmol+/㎏, respectively. Conclusions : Glehnia littoralis are native to the coastal sand dunes, but when cultivated, it is necessary to extend the range of soil selection.

Background : This study was carried out to provide basic data for in-situ conservation of the rare Glehnia littoralis in Korean Midwest. Methods and Results : In Korean Midwest, The average number of plants with Glehnia littora lis were 7 taxa in per plot, and Sinduri was the most abundant in 8 taxa among the surveyed areas. The total number of plants that appeared together were 16 taxa including Glehnia littor alis, the plants were Artemisia capillaris, Asparagus schoberioides, Calystegia soldanella, Care x kobomugi, Carex pumila, Elymus mollis, Glehnia littoralis, Imperata cylindrica var. koenigii, Ischaemum anthephoroides, Ixeris repens, Lathyrus japonica, Miscanthus sinensis, Oenothera bi ennis, Rosa rugosa, Vitex rotundifolia and Zoysia macrostachya. Among them, Carex kobomug i (46.3%), Elymus mollis (15.9%), and Imperata cylindrica var. koenigii (11.7%) were the pla nts with an average coverage of more than 10%. The plants that appeared in all 4 sites in th e survey area were Carex kobomugi and Carex pumila. Conclusions : Rare medicinal plant of Glehnia littoralis was required to be in-situ conservatio n with accompanying plants of coastal sand dunes.

Background : This study aimed to determine the use of proper organic fertilizer through side dressing application in the environmental cultivation of Adenophora triphylla var. japonica Hara. to improve farming income. Methods and Results : In the cultivation of eco-friendly and environmental medicinal plant like Adenophora triphylla var. japonica Hara., it is necessary to use organic instead of chemical fertilizer. Organic fertilizers such as HL, CK, OK were applied three (3) times during the last ten days of July, August, and September. There was no significant difference between CF and NT, in terms of the number of rooting per 1㎡ which was 12.1 -12.9. There were also no significant differences in plant length, leaf length, leaf width and dry weight. The root length was 19.9 ㎝, which was the longest in CK, and 16.8 ㎝, the shortest in ST, but described as no significant difference. The root width was 14.8 – 5.5 ㎜, and the number of rootlet was 5.7 - 7.1, but was considered not a significant difference. The dry weight was 16.6 g in HL, 16.3 g in CK and ST, and 15.6 g in OK, but still there were no significant differences observed. However, it was 14.6 g in NT, which was considered the lowest, thus there was a significant difference. The number of dry root per 10 a was 149 ㎏ which is considered the most in HL, 141 ㎏ in CK, 140 ㎏ in ST, and 138kg in OK yet there were no significant differences observed. While NT only had 123 ㎏ hence, there was a significant difference on the number of dry root per 10a as compared with the group applied with the three organic fertilizers. Conclusion : In conclusion, it is proper to use Organic Fertilizer HL and CK through side dressing application in growing Adenophora triphylla var. japonica Hara.

Background : This project was conducted to determine proper seed harvest time and seed storage methods of Adenophora triphylla var. japonica Hara. Methods and Results : When Adenophora triphylla var. japonica Hara. transplanted this year, seeding can only be done the following year. Therefore, the seeds harvested in the interval of ten (10) days were investigated for seed harvest amount, germination rate, seed storage temperature and storing on container, between the period late August and mid-October. It is when the seed fructification started and ended. The seeds harvested from the first ten (10) days of October to mid October were 87.9% in whole seeds. The proper seed harvesting time was mid October which has a germination rate of 75% in whole seed harvest time. The lowest germination rate of 27.3% was at the germination temperature of 15℃. As the temperature rises, the germination rate increases. In 29℃, the germination rate was at 79% which is the highest; and from 30℃, the germination rate decreased to 71%. When the storage temperature was at 0℃ after storage of 5 months, the germination rate was at 83%. However, after storage of 12 months, it decreased by 7% that was 76%. When in 4℃, after storage of 5 months the germination rate was at 85%. However, after storage of 12 months it decreased by 8% which was 77%. In room temperature after storage of 5 months, germination rate was at 77%, but after storage of 12 months it decreased by 22% which was 55%. When seeds were stored in vinyl container, it was observed that the germination rate was at 86% after 5 months of storage, which was 9% higher than seed stored in paper which was 77%. After 12 months storage, seed in vinyl container had a germination rate of 71%, which was 3% higher than seed in paper at 68%. Conclusion : It is concluded that the proper time of seed gathering of Adenophora triphylla var. japonica Hara. is during the first ten (10) days of October to mid-October. When the long time storage is needed, below zero temperature with vinyl container is more appropriate.

Background : In previous studies, adlay seeds showed a prevalence of diversified fungal flora with the predominant fungal genera being Fusarium (45.6%) and In vitro test showed that fungal toxins like Fumonisin and Zearalenone were produced by Fusarium fujikuroi, F. asiaticum and F. graminearum. Because of this we performed experiments to selecting disinfective chemicals for controlling the Fusarium contamination in the adlay seed. Methods and Results : We carried out the chemical efficacy test such as seed disinfectants selection test appling before planting and pesticides selection test using in the earing season. In the present study, eleven different commercially available seed disinfectant were applied to the adlay seeds. Among 11 seed disinfectants, Hexaconazole+Prochloraz emulsifiable concentrate (EC) and Prochloraz emulsifiable concentrate (EC) had control value of 80% or above against Fusarium species tested. In the pesticides selection test, seven different commercially available pesticides for Fusarium blight (Scab) control were applied and we observed that Metconazole suspension concentrate(SC) strongly inhibited the mycelial growth of 10 Fusarium species all. Conclusion : From the above results, we selected Hexaconazole+Prochloraz EC and Prochloraz EC as a seed disinfectants and Metconazole SC as a pesticide using in the earing season for Scab control.

Background : This experiment was conducted to select GAP applying seed disinfectants in Astragalus membranaceus and Platycodon grandiflorum. Methods and Results : We carried out the chemical efficacy and injury test. For the efficacy test, we investigated fungal detection rate by seed disinfectants and for the chemical injury, we investigated germination rate and emergence rate by seed disinfectants in reference amount and fold amount. These experiments carried out two times. The results obtained are as follows. In the experiment for seed disinfectants selection of Astragalus membranaceus, all tested chemicals such as Tebuconazole emulsifiable concentrate(EC), Thiophanate-methyl + Triflumizole wettable powder(WP), Prochloraz copper chloride complex+Tebuconazole suspension concentrate(SC), Prochloraz emulsifiable concentrate(EC), Fludioxonil wetting liquid(WL) and Hexaconazol+Prochloraz emulsifiable concentrate(EC) had control value of 80% or above against seed contaminated fungi. However two chemicals such as Tebuconazole EC and Prochloraz copper chloride complex+Tebuconazole SC and two chemicals such as Prochloraz EC and Hexaconazol+Prochloraz EC exhibited chemical injury significantly in reference amount and in fold amount respectively, compared to non treated control. In the case of seed disinfectants selection of Platycodon grandiflorum, Prochloraz copper chloride complex+Tebuconazole SC, Prochloraz EC and Hexaconazol+Prochloraz EC had control value of above 80% against seed contaminated fungi except Thiophanate-methyl+Triflumizole WP and Fludioxonil WL. However Hexaconazol+Prochloraz EC and Prochloraz copper chloride complex+Tebuconazole SC exhibited chemical injury significantly in reference amount and in fold amount respectively, compared to non treated control. Conclusion : From the above results, we finally selected three items of seed disinfectants including Thiophanate-methyl+Triflumizole WP and Fludioxonil WL in Astragalus membranaceus and Prochloraz emulsion in Platycodon grandiflorum.