• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.127.1-127.1
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• 2012

The 40.8-MHz VHF coherent scatter ionospheric radar, located in South Korea (Gyeryong, $36.18^{\circ}N$, $127.14^{\circ}E$), has been operating since December 2009 to investigate ionosphere E- and F-region field-aligned irregularities (FAIs) of mid-latitude. During the observation, we found E- and F-region FAIs appeared frequently: continuous echoes during the post-sunrise period and Quasi-Periodic (QP) echoes at nighttime for E region ; strong post-sunset and pre-sunrise FAIs for F region. The characteristics of E- and F-region FAIs are presented in terms of seasonal and local time variations of occurrence during December 2009 to August 2012. In addition, to investigate the correlation with geomagnetic activity to FAIs occurrence, we compared K-index variations to local time occurrence. It is worth to note our occurrence result since long term observation over several years in the mid-latitude has not yet been carried out.

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.8-14
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• 2011

The live-line works are very dangerous because of direct contacts with the distribution line or neighboring contacts. So the purpose of this study is to identify the risk factor by accident occurrence form and accident case analysis, and to suggest the quantified risk index by risk occurrence frequency and risk strength analysis. And the risk index assessment is researched by accident cases analysis on work type. Accident cases of transmission distribution line are researched based on data of the Ministry of Employment and Labor in the last ten-year period (2000~2009). In results of this paper, high risk isn't always a priority of safety measures. Risk occurrence frequency and risk strength have to be considered according to detail work types, work methods and conditions of field work. And safety management measures must be planned according to risk occurrence frequency and risk strength.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.13-16
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• 2011

The occurrence of major pest infestation was compared between conventional tea plantation and organic tea plantation at Sulloc tea garden in Dosun-dong, Seogwipo-si, Jeju-do from 2002 to 2009. Tetranychus kanzawai was observed a lot in the second year, but it waned from late June. There was not much difference between conventional farming and organic farming in terms of pest density. Empoasca onukii was infested in the second year of organic farming compared with conventional farming, which highlighted the fact that second year of organic farming requires a special care. Scirotothrips dorsalis was highly dense in the second and third year of conventional farming, but its occurrence was lowered when the farming technique was shifted to organic farming. The number of Homona magnanima peaked 4 times each year. In 2008, the first year of organic farming, saw high occurrence of 771.2 per trap per year. In 2009, the second year, the population per trap dropped to 80, showing a great variance depending on year. The occurrence of Caloptilia theivora peaked 5 times annually. In 2008, the first year of organic farming, an average of 2,779 pests per trap was found, and in the following year, 4,143 pests were observed. It showed that density rose in organic growing period.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.15-20
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• 2018

In modern society, crime is one of the major social problems. Crime has a great impact not only on victims but also on those around them. It is important to predict crimes before they occur and to prevent crime. Various studies have been conducted to predict crime. One of the most important factors in predicting crime is frequency of crime occurrence. The frequency of crime is widely used as basic data for predicting crime. However, the frequency of crime occurrence is announced about 2 years after the statistical processing period. In this paper, we propose a frequency analysis of crime - related key words retrieved from the web as a way to indirectly grasp the frequency of crime occurrence. The relationship between the number of frequency of crime occurrence and frequency of actual crime occurrence was analyzed by correlation coefficient.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.61-67
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• 1984

In an attempt to obtain a basic information to develop methods of an effective chemical control and disease forecasting of panicle blast of rice, effects of conidial number of the causal fungus, Pyricularia oryzae, collected in different periods and the rate of leaf blast occurrence on the occurrence of panicle blast were investigated. Conidial number the fungus collected in 5 days before and after heading date were closely related with panicle blast occurrence. But no relationship was obtained between the occurrence rate of leaf blast and that of panicle blast. Considering the incubation period of the disease, we presume that the most effective application periods of chemicals are 5-10 days and 10-15 days before heading, when immediate effective chemicals and slow effective chemicals are applied, respectively.

• Korean journal of applied entomology
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• v.27 no.2
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• pp.117-124
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• 1988

An Investigation of insect pests in rice stored was carried out in Jeonnam region of Korea. The total of 2 class, 7 orders 16 families and 25 species were recorded in Lepidoptera; 8, Coleoptera; 11, Orthoptera; 1, Thysanura 1, blattaria; 2, Hymenoptera; 1 and mites; 2 spe-cies. The important species among them were Sitotroga cerealella, Ephestia cautella, Paral-ipsa gularis, Poldia, in Lepidoptera, and Sitophilus orzae, Oryzaephilus surianmensis, Cryptolestes ferrugineus, Tribolium castaneum, Tenebroides mauritanicus, Attagenus japonicus, in Coleoptera and Blatella germanica, in Blattaria and Acarus siro Petrobia latens, in mites. The duration of maximum occurrence were the late June to mid July for Sitotroga cerealella, the mod July to early August for Oryzaephilus surianmensis the mid July to August for Tribolium castaneum, the early July to late July for Sitophilus orzae, the mid June to early July for Attagenus japonicus the mid June to late Spetember for Blatella germanica and the late April to late May for Acarus siro and Petrobia latens, respectively in investigation, Blatella germanica(Blattaria) which was no problem in stored rice insect till now was mainly distributed a coastal plain and period of occurrence was long amount of occurrence was great. Rice weevil has 4 generations under natural conditions and the peak of 1st perood time was ranged from middle of jun. to last decade of Jun., 2nd period was from the lats decade of Jul. to first decade of Aug., 3rd period was from middle of Sep. to late Sep., 4th period was middle of Oct. to early Nov.

• Journal of Veterinary Science
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• v.24 no.2
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• pp.27.1-27.15
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• 2023

Background: The relationships between the postpartum subacute ruminal acidosis (SARA) occurrence and predicted bacterial functions during the periparturient period are still not clear in Holstein cows. Objectives: The present study was performed to investigate the alterations of rumen fermentation, bacterial community structure, and predicted bacterial functional pathways in Holstein cows. Methods: Holstein cows were divided into the SARA (n = 6) or non-SARA (n = 4) groups, depending on whether they developed SARA during the first 2 weeks after parturition. Reticulo-ruminal pH was measured continuously during the study period. Reticulo-ruminal fluid samples were collected 3 weeks prepartum, and 2 and 6 weeks postpartum, and blood samples were collected 3 weeks before, 0, 2, 4 and 6 weeks postpartum. Results: The postpartum decline in 7-day mean reticulo-ruminal pH was more severe and longer-lasting in the SARA group compared with the non-SARA group. Changes in predicted functional pathways were identified in the SARA group. A significant upregulation of pathway "PWY-6383" associated with Mycobacteriaceae species was identified at 3 weeks after parturition in the SARA group. Significantly identified pathways involved in denitrification (DENITRIFICATION-PWY and PWY-7084), detoxification of reactive oxygen and nitrogen species (PWY1G-0), and starch degradation (PWY-622) in the SARA group were downregulated. Conclusions: The postpartum SARA occurrence is likely related to the predicted functions of rumen bacterial community rather than the alterations of rumen fermentation or fluid bacterial community structure. Therefore, our result suggests the underlying mechanisms, namely functional adaptation of bacterial community, causing postpartum SARA in Holstein cows during the periparturient period.

• Proceedings of the Korean Statistical Society Conference
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• 2004.11a
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• pp.237-241
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• 2004

In standard time-to-event or survival analysis, the occurrence times of the event of interest are observed exactly or are right-censored. However in certain situations such as the AIDS data, the incubation period which is the time between HIV infection time and the diagnosis of AIDS is usually doubly censored. That is the HIV infection time Is interval censored and also the time of the diagnosis of AIDS is right censored. In this paper, we Impute the Interval censored infection time using the conditional mean imputation and estimate the coefficient factor of the regression analysis for the incubation period using Gibbs sampler. We applied parametric and semi-parametric methods for the analysis of the Incubation period and compared the results.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.203-209
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• 1983

The occurrence and regional distribution of low temperature and drought during rice cropping period in Korea were studied to characterize the climatic impacts. The long term changes in rice yield, air temperature and precipitation were analyzed, and regional distributions were characterized. The significant climatic impacts on rice yield were heavy rain or flood, drought and low temperature. Since 1910, the occurrence of drought was 29 times, that of flood was 24 times and that of low temperature was 9 times; however, the drought and flood damages were decreased due to expansion of irrigation system since 1970 but low temperature damage was remarkedly increased. The long term changes in air temperature since 1908 in Suweon showed that the 5-year moving average from July to August decreased while that from May to June increased. The occurrence probability of the long term and early term low temperature types were the greatest in Korea and were in order of Suweon, Daegu and Kwangiu. The long term changes in 10-year moving average precipitation from April to June showed a 15 year cycle and recent years were in low precipitation period. The drought frequencies were the highest in Daegu and Pohang area. According to the precipitation from April to June and resevtoir storage at late June, the severest dry area were the Youngnam inland and the southwest coastal area.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.97-103
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• 2010

The four combustion stages in a diesel engine have close correlation among them. Especially, the ignition delay period has significant effect on the following combustion stage. And the period is also one of inevitable combustion processes in the diesel engine. For example, the diesel knocking is a well-known phenomenon due to the long ignition delay period. The interval of the ignition delay period is affected by the mixture formation process in the cylinder. However, in the case of the D.I. diesel engine, the available duration to make the mixture formation of air-fuel is very short. In addition, the means of the mixture formation mainly depends on the injection characteristics and properties of the fuel. It is difficult to make complete mixture. Therefore, an early stage of combustion is violent, which leads to the weakness of noise and vibration. In this study, using the visible engine, we measured the ignition delay period by photo sensor which detect occurrence of flame and presented the factors of the injection characteristics such as kinds of injection system, the injection pressure and the injection timing. The relation between the ignition delay period and cylinder pressure diagram which was concurrently obtained was also estimated.