• Korean journal of applied entomology
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• v.42 no.1
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• pp.43-51
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• 2003

This study was carried out to develop the forecasting model of Pseudococcus comtocki Kuwana for timing spray. Field phonology and temperature-dependent development of p. comstocki were studied, and its stage transition models were developed. p comstocki occurred three generations a year in Suwon. The 1 st adults occurred during mid to late June, and the 2nd adults were abundant during mid to late August. The 3rd adults were observed after late October. The development times of each instar of p. comstocki decreased with increasing temperature up to 25$^{\circ}C$, and thereafter the development times increased. The estimated low-threshold temperatures were 14.5, 8.4, 10.2, 11.8, and 10.1$^{\circ}C$ for eggs, 1st+2nd nymphs, 3rd nymphs, preoviposition, and 1st nymphs to preoviposition, respectively. The degree-days (thermal constants) for completion of each instar development were 105 DD for egg,315 DD for 1st+2nd nymph, 143 DD for 3rd nymph, 143 DD for preoviposition, and 599 DD for 1 st nymph to preoviposition. The stage transition models of p. comstocki, which simulate the proportion of individuals shifted from a stage to the next stage, were constructed using the modified Sharpe and DeMichele model and the Weibull function. In field validation, degree-day models using mean-minus-base, sine wave, and rectangle method showed 2-3d, 1-7d, and 0-6 d deviation with actual data in predicting the peak oviposition time of the 1st and 2nd generation adults, respectively. The rate summation model, in which daily development rates estimated by biophysical model of Sharpe and DeMichele were accumulated, showed 1-2 d deviation with actual data at the same phonology predictions.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.4
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• pp.268-276
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• 2007

Urban atmosphere may play as a harbinger for the future climate change with respect to temperature and $CO_2$ concentration. The Seoul metropolitan area is unique in rapid urbanization and industrialization during the last several decades, providing a natural $CO_2$ dome with increased temperature. This study was carried out to evaluate the feasibility of using the urban-rural environmental gradient in replacement of the IPCC mid-term scenario (after 30-50 years). For this, we measured atmospheric $CO_2$ concentration and air temperature at three sites with different degree of urbanization (Seoul, Suwon, and Icheon). Results from 11-month measurement can be summarized as follows: (1) The annual mean $CO_2$ concentration across 3 sites was in the order of Seoul (439 ppm) > Suwon (419 ppm) > Icheon (416 ppm), showing a substantial urban-rural environmental gradient. (2) The diurnal fluctuation in $CO_2$ concentration was greater in summer than in winter, showing the effect of photosynthesis on local $CO_2$ concentration. (3) The daily maximum $CO_2$ concentration was observed at 0500 LST in spring and summer, 0800 LST in autumn, and 0900 LST in winter, showing the sunrise-time dependence. (4) The observed hourly maximum $CO_2$ concentration averaged for the whole period was 446 ppm in Seoul at 0700 LST, while the minimum was 407 ppm in Suwon at 1500 LST. (5) Compared with the background atmospheric concentration of $CO_2$ in Anmyeon-do (377.4 ppm annual mean), $CO_2$ concentration of the study sites was higher by 14% in Seoul, by 10% in Suwon, and by 9% in Icheon. The observed $CO_2$ concentration in Seoul reached already 98% of the 2030-2040 projection (450 ppm) and 80% of the 2040-2050 projection (550 ppm) under the IPCC BAU scenario, showing a feasibility of using the $CO_2$ dome of Seoul as a natural experimental setting for the mid-term climate change impact assessment.

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.1
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• pp.15-30
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• 1998

The variation of the catches of Skipjack(Euthynnus pelamis) and the relationships between the SST and the fishing ground is examined using the catches data of skipjack obtained by Iwawada Fisheries Cooperative of Chiba Prefecture in Japan from 1982 to 1988. The annual mean catch for Skipjack was 151,375.1kg. the annual fluctuation of catch was that the catch in 1984 was increasing, but it was decreased less than 50% in 1985, and was repeated after being a little recovered in 1986, and it was recovered with the level of 1984 in 1988. The fluctuation of catch for Skipjack in every fishing term is that daily mean catch of the primary fishing term (January, February and March) is 894.6kg, but the middle fishing term(April and May) more than four times of the primary fishing term is 3,666.0kg, the last fishing term(June and July) was decreasing at 767.9kg and the fishing ground gradually becomes extinct. The annual mean SST in fishing ground was an extent of from $19.0^{\circ}C$ to $20.2^{\circ}C$, the mean SST of every year except 1983 was from $19.0^{\circ}C$ to $19.9^{\circ}C$. It is said that the optimum SST of Skipjack in Sotobo sea area is the degree of $19.0^{\circ}C$. Therfore, the thing which will guess the time and the location appeared the optimum SST is the very important factor to operate efficiently. About the extent of SST in fishing ground, it was from $17.0^{\circ}C$ to $19.0^{\circ}C$ on March, from $17.5^{\circ}C$ to $20.5^{\circ}C$ on April and from $17.5^{\circ}C$ to $23.5^{\circ}C$ on May, which the extent of SST was gradually larger and larger, on June from $21.0^{\circ}C$ to $23.5^{\circ}C$, fishing ground was formed only the degree of SST more than $21.0^{\circ}C$.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.190-204
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• 2018

The probability of safe cropping and the major phenological stages in rice were assessed using daily mean temperature data from 1981 to 2016 at 27 sites in North Korea. The threshold temperatures for early marginal transplanting date (EMTD), marginal harvesting date (MHVD), safe marginal heading date (SMHD), and cumulative temperature-based heading date (CTHD) were set to be $14^{\circ}C$, $13^{\circ}C$, $22^{\circ}C$ for 40 days after heading, and cumulative temperature of $1200^{\circ}C$ to MHVD, respectively. The safe heading date (SHD) was assumed to be either SMHD or CTHD whichever was earlier. It was also assumed that the minimum requirement for the suitability of safe rice cropping was met when both SMHD and CTHD appeared along with the time period of 60 days or more from EMTD to SHD. It was analyzed that 17 sites (Kaesong, Haeju, Yongyon, Singye, Sariwon, Nampo, Pyongyang, Anju, Kusong, Sinuiju, Changjon, Wonsan, Hamhung, Pyonggang, Huichon, Supung, Kanggye) had 90% or higher probability, two sites (Yangdok, Sinpo) had 80-90% probability, and eight sites (Kimchaek, Chunggang, Chongjin, Sonbong, Changjin, Pungsan, Hyesan, Samjiyon) had less than 80% probability of the safe rice cropping. For each region, the representative EMTD, SHD, and MHVD were analyzed using the 80 percentile of total years tested. The ranges for EMTD, SHD, and MHVD were May 4 in Sariwon~May 24 in Sinpo, June 21 in Kanggye~August 11 in Haeju, and September 17 in Kanggye~October 16 in Haeju and Changjon, respectively. Time durations from EMTD to SHD and from SHD to MHVD were 67~97 days and 57~72 days, respectively, depending on the regions. This study would facilitate modeling efforts for rice yield simulation in future studies. Our results would also provide basic information for practical researches on the rice cropping system in North Korea.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.4
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• pp.196-206
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• 2012

Studies of seasonal changes in $C_3/C_4$ mixed communities are rare, particularly in Asian summer monsoon climate zones. In our present study, seasonal changes in the profile and coverage of $C_3$ and $C_4$ plants were investigated in 2009 in Haenam, Yeongdong and Cheorwon regions of South Korea (all at different latitudes). The aim was to estimate the impacts of temperature and sunshine duration on species composition and transition timing of the $C_3$ and $C_4$ plants. From our results, the number of $C_3$ plants was found to increase from early spring to mid-May, and then decrease again until September in the Haenam and Yeongdong regions, but continuously increase from early spring to September in the Cheorwon region under relatively low summer temperatures. On the other hand, the number of $C_4$ plants increased from June or July to September in all three regions. These seasonal changes in species number and ratio have a direct impact upon species diversity which is highest when there are no dominant species. The relative coverage and relative summed dominance ratio (SDR') of the $C_3$ plants decreased from spring to autumn, but increased for the $C_4$ plants during this time in an exponential fashion with increasing accumulated temperature and sunshine duration. The transition timing from $C_3$ to $C_4$ plants occurred when the sum of sunshine duration for the days with daily mean temperature above $5^{\circ}C$ was 1017 hrs for the SDR'.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.2
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• pp.260-267
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• 1995

In temperate zone planting rice at different date subjects the Crop to different climatic condition. The present study aimed at comparison of the change in source-sink relationship of the Japonica(J) and that of IndicaxJaponica(I$\times$J) type rice cultivars caused by shift of heading date. Two J- and two I$\times$J-type cultivars were made to head on August 16, August 26, and September 5. Sink capacity was changed by shift of heading date in different mode between the types of cultivars. In both types major determinant of sink capacity was number of effective tillers, and the number of spikelets per panicle was the minor. In J-type earlier planting/heading was beneficial to increased panicle numbers and this was due mainly to a larger diurnal difference in temperature. I$\times$J-type cultivars favored a higher daily mean temperature to increase the sink capacity. The ability of source at heading, in terms of leaf area per panicle, chlorophyll content per spiklet, photosynthetic ability of leaves per unit area at 25$\^{\circ}C$, carbohydrate and N contents of leaves, was not so different among different heading dates in both types. However, the source activity was governed principally by temperature during grain filling. The J-type cultivars headed on Sept. 5 and I$\times$J-type cultivars headed later than August 16 could not have had sufficient source activity in grain filling due to lower temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.188-202
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• 1997

The seasonal variability of the sea surface winds over the last Sea of Korea (Japan Sea) is investigated by means of empirical orthogonal function (EOF) analysis. The combined representation of fields of three climatic variables by empirical orthogonal functions is discussed. The eigenvectors are derived from daily sea level pressure, wind speed and 10-day mean sea surface temperature (SST) during 15 years $(1978\~1992)$. The spatial patterns of the mean pressure are characterized by the high pressure in the western part and the low pressure in the eastern part. The spatial distribution of the standard deviation (SD) of pressure are characterized by max SD of 6.6 mb near the Vladivostok, and minima along the coast of the Japan. In Vladivostok, the maxima of SD of SST and south-north wind (WV) were also occurred. The representation of fields of individual meteorological variables by EOF shows that the first mode of the west-east wind (WU) explain over $47.3\%$ of the variance and the second mode of WU represents $30\%$. Especially, the first mode of the WV explain $70.9\%$ of the variance and their time series coefficients show 1-cpy, 0.5-cpy frequency spectrum. The spatial distribution of the first mode eigenvectors of SST are characterized by maximum near Vladivostok. The combined representation of fields of several variables (pressure, wind, SST) reveals that the first mode magnitudes of the variance of the combined eigenvectors (WU-PR) are increased. By means of this result, the 1-year peak and the 6-months peak are remarkable. In the three combined patterns (wind, pressure, SST), the second mode of the eigenvector (wind) is affected by the SST. Their time coefficients of the first mode show noticeable 1-year peak. The spectral analysis of the second mode shows broad seasonal signal with the period of 4-months and a significant peak of variability at 3-month period.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.4
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• pp.239-249
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• 2020

Rice flour varieties have been developed to replace wheat, and consumption of rice flour has been encouraged. damage related to pre-harvest sprouting was occurring due to a weather disaster during the ripening period. Thus, it is necessary to develop pre-harvest sprouting rate prediction system to minimize damage for pre-harvest sprouting. Rice cultivation experiments from 20 17 to 20 19 were conducted with three rice flour varieties at six regions in Gangwon-do, Chungcheongbuk-do, and Gyeongsangbuk-do. Survey components were the heading date and pre-harvest sprouting at the harvest date. The weather data were collected daily mean temperature, relative humidity, and rainfall using Automated Synoptic Observing System (ASOS) with the same region name. Gradient Boosting Machine (GBM) which is a machine learning model, was used to predict the pre-harvest sprouting rate, and the training input variables were mean temperature, relative humidity, and total rainfall. Also, the experiment for the period from days after the heading date (DAH) to the subsequent period (DA2H) was conducted to establish the period related to pre-harvest sprouting. The data were divided into training-set and vali-set for calibration of period related to pre-harvest sprouting, and test-set for validation. The result for training-set and vali-set showed the highest score for a period of 22 DAH and 24 DA2H. The result for test-set tended to overpredict pre-harvest sprouting rate on a section smaller than 3.0 %. However, the result showed a high prediction performance (R2=0.76). Therefore, it is expected that the pre-harvest sprouting rate could be able to easily predict with weather components for a specific period using machine learning.

• Korean Journal of Weed Science
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• v.13 no.4
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• pp.210-233
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• 1993

The herbicide has become indispensable as much as nitrogen fertilizer in Korean agriculture from 1970 onwards. It is estimated that in 1991 more than 40 herbicides were registered for rice crop and treated to an area 1.41 times the rice acreage ; more than 30 herbicides were registered for field crops and treated to 89% of the crop area ; the treatment acreage of 3 non-selective foliar-applied herbicides reached 2,555 thousand hectares. During the last 25 years herbicides have benefited the Korean farmers substantially in labor, cost and time of farming. Any herbicide which causes crop injury in ordinary uses is not allowed to register in most country. Herbicides, however, can cause crop injury more or less when they are misused, abused or used under adverse environments. The herbicide use more than 100% of crop acreage means an increased probability of which herbicides are used wrong or under adverse situation. This is true as evidenced by that about 25% of farmers have experienced the herbicide caused crop injury more than once during last 10 years on authors' nationwide surveys in 1992 and 1993 ; one-half of the injury incidences were with crop yield loss greater than 10%. Crop injury caused by herbicide had not occurred to a serious extent in the 1960s when the herbicides fewer than 5 were used by farmers to the field less than 12% of total acreage. Farmers ascribed about 53% of the herbicidal injury incidences at their fields to their misuses such as overdose, careless or improper application, off-time application or wrong choice of the herbicide, etc. While 47% of the incidences were mainly due to adverse natural conditions. Such misuses can be reduced to a minimum through enhanced education/extension services for right uses and, although undesirable, increased farmers' experiences of phytotoxicity. The most difficult primary problem arises from lack of countermeasures for farmers to cope with various adverse environmental conditions. At present almost all the herbicides have"Do not use!" instructions on label to avoid crop injury under adverse environments. These "Do not use!" situations Include sandy, highly percolating, or infertile soils, cool water gushing paddy, poorly draining paddy, terraced paddy, too wet or dry soils, days of abnormally cool or high air temperature, etc. Meanwhile, the cultivated lands are under poor conditions : the average organic matter content ranges 2.5 to 2.8% in paddy soil and 2.0 to 2.6% in upland soil ; the canon exchange capacity ranges 8 to 12 m.e. ; approximately 43% of paddy and 56% of upland are of sandy to sandy gravel soil ; only 42% of paddy and 16% of upland fields are on flat land. The present situation would mean that about 40 to 50% of soil applied herbicides are used on the field where the label instructs "Do not use!". Yet no positive effort has been made for 25 years long by government or companies to develop countermeasures. It is a really sophisticated social problem. In the 1960s and 1970s a subside program to incoporate hillside red clayish soil into sandy paddy as well as campaign for increased application of compost to the field had been operating. Yet majority of the sandy soils remains sandy and the program and campaign had been stopped. With regard to this sandy soil problem the authors have developed a method of "split application of a herbicide onto sandy soil field". A model case study has been carried out with success and is introduced with key procedure in this paper. Climate is variable in its nature. Among the climatic components sudden fall or rise in temperature is hardly avoidable for a crop plant. Our spring air temperature fluctuates so much ; for example, the daily mean air temperature of Inchon city varied from 6.31 to $16.81^{\circ}C$ on April 20, early seeding time of crops, within${\times}$2Sd range of 30 year records. Seeding early in season means an increased liability to phytotoxicity, and this will be more evident in direct water-seeding of rice. About 20% of farmers depend on the cold underground-water pumped for rice irrigation. If the well is deep over 70m, the fresh water may be about $10^{\circ}C$ cold. The water should be warmed to about $20^{\circ}C$ before irrigation. This is not so practiced well by farmers. In addition to the forementioned adverse conditions there exist many other aspects to be amended. Among them the worst for liquid spray type herbicides is almost total lacking in proper knowledge of nozzle types and concern with even spray by the administrative, rural extension officers, company and farmers. Even not available in the market are the nozzles and sprayers appropriate for herbicides spray. Most people perceive all the pesticide sprayers same and concern much with the speed and easiness of spray, not with correct spray. There exist many points to be improved to minimize herbicidal phytotoxicity in Korea and many ways to achieve the goal. First of all it is suggested that 1) the present evaluation of a new herbicide at standard and double doses in registration trials is to be an evaluation for standard, double and triple doses to exploit the response slope in making decision for approval and recommendation of different dose for different situation on label, 2) the government is to recognize the facts and nature of the present problem to correct the present misperceptions and to develop an appropriate national program for improvement of soil conditions, spray equipment, extention manpower and services, 3) the researchers are to enhance researches on the countermeasures and 4) the herbicide makers/dealers are to correct their misperceptions and policy for sales, to develop database on the detailed use conditions of consumer one by one and to serve the consumers with direct counsel based on the database.

• Journal of Veterinary Clinics
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• v.20 no.1
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• pp.12-21
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• 2003

In this study, we evaluated effects of three anastomotic techniques of small intestine on adhesions in the dog. Twenty six healthy mixed dogs were randomly assigned to three groups. Group I(n = 8) was sutured with a simple continuous suture, group II(n = 7) was sutured with a simple interrupted approximating suture and group III(n = 11) was sutured with a single layer continuous Connell suture. On completion of any intestinal anastomosis, a pedicle of greater omentum was wrapped around the suture line in all experimental dogs. One percent sodium carboxymeth-ylcellulose (5ml/kg) was administrated into the abdomen by feeding tube prior to closing the last part of peritoneum in all dogs. Postoperative adhesions were evaluated at 14th day after operation. The adhesions consisted primarily in two dogs in group I, three dogs in group II and group III. There were adhesions between intestinal serosal surfaces in eight dogs in all groups, but there were no intestinal serosa-visceral peritoneum adhesion and intestinal serosa-mesentery adhesion. Mean adhesion scores were less than score 2 in all groups. Between anastomotic site and omental graft, there were 13.13$\pm$4.97 mm (mean$\pm$S.D.) adhesion formation in group I and 17.29$\pm$4.68 mm in group II and 14.64$\pm$3.80mm in group III. A simple continuous suture resulted in the least adhesion formation and a simple interrupted approximating suture resulted in the greatest adhesion formation among the groups. However, there were no significant differences among three suture techniques in the severity of adhesions. Intestinal intussusception only encountered in one dog during the 14 days, the dog operated and survived. Daily monitoring of temperature, activity, appetite, defecation and micturition were done. All of those vital signs were within normal values and there were no obvious differences among the groups. In conclusion, even though there were no significant differences among three groups, a simple continous suture pattern is recommended to prevent adhesions when operating intestinal anastomosis in dogs.