• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.1
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• pp.58-67
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• 2021

This paper describes the development for the dual thrust rocket motor with two types of propellants with different combustion characteristics. We developed the composition of two kinds of propellant to be applied to a rocket motor, and improved a propellant charging process in a free grain type to improve the adhesion method and the problems of adhesion between different propellants. In addition, to meet the ignition phenomenon as a small rocket motor, the ignition delay was improved by applying a nozzle plug developed in a high density foam. The propulsion rocket motor reflecting this design and the improved manufacturing process was evaluated through a ground performance test.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.6_1
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• pp.447-454
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• 2013

The geolocation accuracy of SAR satellite imagery is affected by orbit and sensor information and external variables such as DEM accuracy and atmospheric delay. To predict geolocation accuracy of KOMPSAT-5 and KOMPSAT-6, this paper uses TerraSAR-X imagery which has similar spec. Simulation data for sensitivity analysis are generated using range equation and doppler equation with several key error sources. As a result of simulation analysis, the effect of sensor information error is larger than orbit information error. Especially, onboard electronic delay needs to be monitored periodically because this error affects geolocation accuracy of slant range direction by 30m. Additionally, DEM accuracy causes geolocation error by 20~30m in mountainous area and atmospheric delay can occur by 5m in response to atmospheric condition and incidence angle.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.4
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• pp.339-346
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• 1992

Self-and reciprocal-graftings were made between soybean varieties(cv.Hwangkeumkong, Paldalkong, Bokwangkong and Jangkyongkong) to assertain the relative role of shoot and root in soybean growth and yield determination. The influence of grafting per se on plant height and leaf number on main stem were negligible as evidenced by the insignificant differences between self-and reciprocal-graftings. The effect of grafting on flowering was different between different set of varieties grafted reciprocally. Self grafting delayed flowering 2 days and reciprocal grafting delayed another 2 days, in general. The effects of grafting on dry weights of different plant parts except pod were also insignificant. Reciprocal grafting increased pod dry weight in Hwangkeumkong and Paldalkong regardless whether they were used as scion or stock. Reciporcal grafting also influenced dry weights of Bokwangkong and Jangkyongkong significantly, but the response was different from those of Hwangkeumkong or Paldalkong. Jangkyongkong, when used as stock, decreased total dry weight of Bokwangkong significantly through the reduction of pod and stem dry weights. Stem diameter was increased by grafting, however, grafting decreased number of branches in all varieties. The average yields of self-and reciprocal-grafting were decreased by 11% and 24%, respectively, comparing to that of non-grafting, while average yield of reciprocal grafting was 14% lower than that of self grafting. Stem weight of grafted soybeans was decreased by 29-32% comparing to that of non-grafted soybeans, but the difference between self and reciprocal graftings was negligible. The genetic characteristics of scion was found to be more important than those of stock in determination of yield and stem weight. It was also indicated that varieties and characteristics are different in response to grafting.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.2
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• pp.151-160
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• 1997

In this paper, we have carried out the DS/CDMA with a suppressed pilot channel, which is used in receiving coherently with Rake diversity and in synchronizing the chip timing, in the mobile satellite communication. Also, we have investigated the envelope variation of a shadowed Rician fading simulator, and analyzed the error performences of DS/CDMA in the mobile satellite communication. The results showed that the error performance in the Heavy shadowing environment might be degraded more than in the Rayleigh fading environment since the fading envelopes in the former environment are varied randomly compared with those in the latter environment. And the performence of DS/CDMA system could be improved about 10 dB compared with that of narrowband QPSK system. In conclusion, DS/CDMA with a suppressed pilot channel had the best performance in the case of the suppressed pilot channel to transmission power ratio $\beta$=-8 dB, the number of complex delay profiles $N_{profile}$=32, and using these values, the error performance of DS/CDMA in Light shadowing environment was identical to the ideal QPSK error performance.

• Journal of the Korean association of regional geographers
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• v.4 no.1
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• pp.43-56
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• 1998

The purpose of this study is to identify distributional characteristics of climatic elements and to analyze synoptic characteristics on the pressure fields for spring droughts in Korea. In the distributions of minimum temperature during the spring droughts, positive anomalies and negative anomalies are mixed up, but in March the negative anomaly areas are widely distributed in Korea. It implies that the droughts of March have more frequent occurrences of the west-high, east-low pressure patterns. In the maximum air temperatures, the positive anomalies appear in Korea. It indicates that the spring droughts have rain days, cloud amount and humidities less than normal. As a result, the amount of evaporation is increased in Korea. In the pressure anomaly of surface pressure fields, the positive anomalies appear in the west, negative anomalies in the east in March, but in May the positive anomalies appeared zonally around the Korean peninsula. It indicates that March droughts have more frequent occurrences of the west-high. east-low patterns, but in May the Korean Peninsula has more frequent recurrences of the migratory anticyclone patterns. The height anomaly patterns of 500hPa pressure surface in spring droughts are similarly shown to those of surface fields. In March droughts, the positive height anomalies appear in the west, the negative height anomalies in the east, but in April the negative height anomaly areas are extended to the west part. In May the positive anomalies appear zonally around the Korean Peninsula, and strong positive height anomalies appear around the Kamchatka Peninsula and the sea of Okhotsk. These are the result of circulations that inhibit the eastward movement of westerlies and that has persistent anticyclone circulation patterns around the Korean Peninsula. As a result, the zonal indices of westerlies during March and April droughts are lower than normal, but higher in May. These data indicate that early spring droughts are associated with weak zonal flow, but the late spring droughts are obviously related with strong zonal flow. In addition, during early spring droughts the abnormally deep trough over the west coast of the North Pacific Ocean that accompanied the anticyclone was associated with frequent advection of air from the dry regions in the Central Asia into the Korean Peninsula. The atmospheric circulation patterns at the height of the 500hPa pressure surface in May was quite different from March and April circulation patterns. Instead of the abnormal ridge in the west and trough in the east, the circulation pattern in May was characterized by a much stronger than normal anticyclone over the Korean Peninsula. Also, the zonal indices of westerlies in May are higher than normal. The occurrences of drought in early spring, therefore, have mechanism different from those of late spring.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.3
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• pp.161-169
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• 2005

With various Korean domestic soybeans, growth and yields analysis were conducted to select the suitable soybean cultivars for cultivation in paddy field. Distinctive aspects of the soybean growth were observed in paddy field such as retarded growth of top plants and roots, relatively higher T/R ratio followed by overgrowth of top plant. However, growth and yields were significantly different among the cultivars showing 134kg/10a in Paldokong and 385 kg/10a in Doremikong. At V5. and R2 stage, highly positive correlations $(r=0.76^{**}\~0.91^{**})$ were observed between leaf area and dry weight of top plant and/or root. T/R ratio was negatively correlated with dry weight of root $(r=-0.37^*)$ at V5 stage, while significantly correlated with leaf area $(r=-0.37^{**})$ and dry weight of top plant $(r=0.65^{**})$at R2 stage. Among the characters, only 100-seed weight was significantly correlated with yield. Considering the growth characters, 37 cultivars could be included in 3 different groups and genotypic properties such as maturity and growth habit were similar in each group. Nine cultivars in group 1 showed retarded growth from V5 to R2 stage, relatively lower T/R ratio, and good seed ripening. Average yields of the cultivers was 257kg/10a. In group 2, 12 cultivars showed higher T/R ratio due to overgrowth of top plant and lowest average yields (230 kg/l0a) due to poor seed ripening. Sixteen cultivars in group 3 grew fast from V5 to R2 stage representing late maturity traits, low T/R ratio, and good seed ripening. Average yields of the cultivars was highest among groups showing 270kg/l0a. In results, stable self-sufficiency of soybean yields could be expected by selective cultivation with high yielding cultivars ranging from 301 to 385kg/10a, such as Shinpaldalkong 2, Sohokong, Doremikong, Keumkangkong, Bukangkong, Dajangkong, and Geomjeongkong 2, or with cultivars included in group 3.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.311-321
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• 1994

Experiments were conducted to evaluate the efficacy of ground and foliar sprinkling of natural water for control of the pine needle gall midge, Thecodiplosis japonensis, by disturbing the reproductive behavior of adults such as copulation and oviposition. Diurnal ground spray for whole area application and foliar spray for single tree treatment were tested at day time during the period of adult emergence. The results obtained are as follows : 1. The population density of overwintering larvae in soil was not affected by the water spray during the adult emergence period. 2. Spraying the water showed no effect on the whole period and number of adult emergence, but retarded early emergence and facilitated Late emergence. The difference in the emerging time by 50% emergence day was approximately 7 days. 3. Ground spray was significantly different from control in gall formation rates but was not sufficient for effective control. As a single-tree treatment, the foliar spray was found to be highly effective for control of the pine needle gall midge, Average gall formation of spray plots and untreated ones were 2.6% and 38%, respectively ; control value exceeded 90%. 4. Ground spray of water was not effective in reducing larvae in gall of needle. Foliar spray, however, reduced 45% of larval numbers. 5. Foliar spray accelerated shoot growth by 15%-18%. 6. Foliar spray was highly effective for the control of sucking insects, such as mites and aphids on pine trees.

• Journal of Bio-Environment Control
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• v.19 no.1
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• pp.55-62
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• 2010

This study was conducted to find out the effect of diniconazole treatment by seed soaking on the stretching of tomato and cucumber seedlings. The emergence rate of tomato and cucumber seed was decreased as diniconazole concentration was higher and soaking period was longer. The emergence rate of tomato seedlings was lower as the soaking period was longer in $1mg{\cdot}L^{-1}$ concentration treatments, although there was no significant difference. The other concentration treatment (10, 50, and $100mg{\cdot}L^{-1}$) reduced emergence rate of tomato seedlings outstandingly in higher concentration and longer treated period, but 90% of treated seeds emerged at 10 days after sowing. As the concentration of diniconazol was higher and soaking period was longer, plant height and growth rate of seedlings were retarded. There covery of internodes growth was faster in lower concentration and shorter soaking period. The top and root fresh weight and dry weight of tomato and cucumber seedlings was not influenced by $1mg{\cdot}L^{-1}$ concentration, but these growth characteristics were reduced in higher concentration and longer soaking period. The dwarfed cucumber seedlings treated by diniconazol showed normal growth rate after planting and their male and female flower was set normally. These results suggest that the proper concentration and soaking period of diniconazol may be $10mg{\cdot}L^{-1}$ concentration for 12 hours in tomato seed, and $1mg{\cdot}L^{-1}$ concentration for 24 hours in cucumber seed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.4
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• pp.451-459
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• 1995

In order to clarify the growth characteristic and Brix degree at different internodes, four varieties that are M81E 71-1, a Rio, a Sart and a Tamurama were seeded on, Apr. 5, Apr. 15, Apr. 25, May 5 and May 15, respectively. Delayed seeding increased plant hight and the growth pattern of the stem diameter and weight was tapesed off and lighted to upper location. Brix degree of internode was rapidly increased from just after heading date, and was slowly increased by rising upper side till before heading date. Brix degree of middle location(6th internode) was the highest of the stem in after heading date and interior side was the lowest. Brix percentage of 40∼45 days after heading had more than 15% in case of being seeded from Apr. 5 to May 5. Sweet sorghum that was seeded on May 15 was more than 17% in the Brix percentage of 35 days after heading and so the suitable seeding date in sourthern district was suggested on May 5. The plethora of soil moisture by rainfall was made decently lower Brix degree in 130∼140 days after seeding. Among the length and the diameter of internode, and Brix degree had negative correlation, between diameter and weight of internode were significantly positive correlation. But correlation coefficient had been a little bit different by varieties.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.3
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• pp.145-154
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• 2014

The road network becomes more complex and extensive. Therefore, the inconveniences are caused in accordance with the time delay of the restoration of damaged roads, demands for excessive costs on information collection, and limitations on acquisition of damage information of the roads. Recently, road centric spatial information is gathered using mobile multi sensor system for road inventory. But expensive MMS(Mobile Mapping System) equipments require high maintenance costs from beginning and takes a lot of time in the data processing. So research is needed for continuous maintenance by collecting and displaying the damaged information on a digital map using low cost mobile camera system. In this research we aim to develop the techniques for mosaic with a regular ground sample distance using successive image from oblique camera on a vehicle. For doing this, mosaic image is generated by estimating the homography of high resolution oblique image, and the ground sample distance and appropriate overlap are analyzed using high resolution aerial oblique images which contain resolution target. Based on this we have proposed the appropriate overlap and exposure interval for mobile road inventory system.