• The Korean Journal of Applied Statistics
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• v.37 no.2
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• pp.225-237
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• 2024

In the analysis of competing risks data, some of covariates may not be fully observed for some subjects. In such cases, excluding subjects with missing covariate values from the analysis may result in biased estimates and loss of efficiency. In this paper, we studied multiple imputation and the augmented inverse probability weighting method for regression parameter estimation in the cause-specific proportional hazards model with missing covariates. The performance of estimators obtained from multiple imputation and the augmented inverse probability weighting method is evaluated by simulation studies, which show that those methods perform well. Multiple imputation and the augmented inverse probability weighting method were applied to investigate significant risk factors for the risk of death from breast cancer and from other causes for breast cancer data with missing values for tumor size obtained from the Prostate, Lung, Colorectal, and Ovarian Cancer Screen Trial Study. Under the cause-specific proportional hazards model, the methods show that race, marital status, stage, grade, and tumor size are significant risk factors for breast cancer mortality, and stage has the greatest effect on increasing the risk of breast cancer death. Age at diagnosis and tumor size have significant effects on increasing the risk of other-cause death.

• Journal of the Korean Society of School Health
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• v.37 no.1
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• pp.22-32
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• 2024

Purpose: The purpose of this study is to compare sociocultural attitudes toward appearance, appearance satisfaction, and peer relationships between male and female middle school students, and to compare the effects of these variables on self-esteem in students of different genders. Methods: Data were collected in August and September of 2023 and analyzed using SPSS 24.0. Data were collected from 289 male and 240 female students through a survey, and descriptive statistics, x2 test, t-test, Scheffé test, and multiple regression analysis were conducted. Results: Female students showed significantly higher scores for sociocultural attitudes toward appearance (3.06±0.77 vs. 2.82±0.74), significantly lower scores for appearance satisfaction (2.55±0.46 vs. 2.71±0.40), and significantly higher scores for peer relationships (3.46±0.69 vs. 3.00±0.78) than male students. Additionally, self-esteem was significantly lower in female students (2.84±0.59) than in male students (2.95±0.51). As a result of adjusting for weekly allowance, subjective academic achievement, family economic status, stress, and experience of sadness or despair, which were significant in the univariate analysis, self-esteem increased as appearance satisfaction (p for all <.001) and peer relationships increased in both male (p=.009) and female (p<.001) students. In addition, sociocultural attitudes toward appearance did not have a significant impact on self-esteem in both male and female students. Among general characteristics, weekly allowance, subjective academic achievement, and stress were found to have a significant effect on self-esteem in both genders. Relationships with parents had a significant effect on self-esteem only in male students, and experience of sadness or despair had a significant effect only in female students. Conclusion: In order to improve self-esteem in both boys and girls, appearance satisfaction and peer relationships should be improved. As boys with poor relationships with their parents and girls with high levels of sadness or despair are particularly likely to have low self-esteem, they are to be considered as a high-risk group.

• Journal of Applied Biological Chemistry
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• v.57 no.3
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• pp.267-277
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• 2014

Objective of this paper is to assess the available data on the pesticide uses and regulations in the golf courses, and provide the nationwide systematic management options. Numbers of golf courses in Korea are rapidly increasing from 2000s and reached at 421 sites by the end of 2011. Accordingly pesticide usage has been increased with years in direct proportion to the increasing number of golf courses. Amounts of pesticide applied in 2011 were 118,669 kg as of an active ingredient and were in the orders of fungicides (54.9%) > insecticides (24.4%) > herbicides (13.3%) > growth regulators (0.1%). Average pesticide usages in 2011 were 280.9 kg per golf course and $5.4kg\;ha^{-1}$. Frequencies of the residual pesticide detections in green and turf were higher than those in fairway and soil, respectively. Residue of highly toxic pesticides was not detected in golf courses. Ministry of Environment in 2010 has developed the 'golf course pesticide monitoring and management system' which is the advanced online registry for kind and amount of pesticides applied in each golf course. This system is intended for monitoring of the pesticide uses and residual levels and protecting the environmental pollution from pesticides in the golf course. In 2009, management of pesticides in the golf courses became the task of Ministry of Environment, being merged from many federal agency and ministries. The protocol for the site-specific best management practices, on which to base results from the risk assessment, should be set for pesticides in the golf to minimize the environmental impacts.

• Journal of Animal Science and Technology
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• v.44 no.3
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• pp.351-360
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• 2002

The Korean fresh pork loins in vacuum packaged were obtained from three different Korean export companies and investigated for microbiological and sensory properties. The fresh pork loins were stored at 2$^{\circ}C$ for 50 days and analyzed with an interval of 5$\sim$10 days. The results were as follows: The overall numbers of total plate counts and coliform bacteria were higher in swab method than in meat sampling method. The total plate counts in the loins from the company I were maintained low levels ($\prec$10$^5$ cfu/$cm^2$ or $\prec$10$^5$ cfu/g) for entire storage periods(50 days at 2$^{\circ}C$), whereas the loins from the company III had high levels when they were compared to the domestic standard for the allowance limit. The samples from the company III showed that total plate counts were over 106 after about 30 days when determined by meat sampling method and total plate counts were over 106 after 15 days when determined by swab method. The overall numbers of coliform bacteria were also significantly lowest in the samples from the company I, whereas they were highest in the company III. Therefore, all meat companies will have to make an effort to prevent bacterial contamination in each stage such as slaughtering, marketing and consumer in order to ensure the production of safe meat and the extension of shelf-life. For fresh products, scores of intramuscular fat were higher in samples form the companies II and III than those from the company I when visibly evaluated with the standard. There were no significant differences in scores of meat color, drip and fresh meat flavor. However, the samples from the company I had the lowest score of off-flavor and highest score of overall acceptability. For cooked products, there were no significant differences in meat flavor, off-flavor, juiciness and overall acceptability.

• Journal of Korean Society of Forest Science
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• v.87 no.4
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• pp.631-641
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• 1998

The objectives of this study were 1) to classify the types of Quercus mongolica stands at Mt. Joongwang and compare their quality, and 2) to determine the proper future tree number of Q. mongolica per ha and the appropriate distance between the future trees. The results from this study were as follows : Q. mongolica stands at Mt. Joongwang was classified into four types, pure Q. mongolica stand as stand type I, Q. mongolica - hardwood stand as stand type II, Q. mongolica - Pines densiflora stand as stand type III, Hardwood - Q. mongolica stand as stand type IV, according to mixture rate in stand volume. Stand type IV showed the best quality stem of Q. mongolica among the stand types, and the stem quality of Q. mongolica in Q. mongolica stand mixed with hardwood as stand types II and IV was better than those in pure Q. mongolica stand as stand type I and in Q. mongolica - P. densiflora stand as stand type III. If the management goal for Q. mongolica stand is to produce its high quality-timber, it is desirable to sustain proper mixture rate of Q. mongolica with another hardwoods. The proper number of future trees in pure Q. mongolica stand as stand type I was 122trees/ha and reasonable distance between the future trees was 9.15m. The distance between future trees in other stand types was 7.2m to 9.3m for stand types II and IV, while 8.0m for stand type III. Thus, the classification of Q. mongolica stand type based on stand character and maturity, and proper stem number of future tree and optimum distance between future trees would be a useful forest tending work.

• Korean Journal of Heritage: History & Science
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• v.49 no.4
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• pp.80-95
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• 2016

This study sought to disclose the problems surrounding the erroneous explanation of the title of the musical script 'Jeongdaeeop,' which is Jongmyojeryeak(Jongmyo Shrine ritual music), shown in Daeakhubo, Korea's treasure No.1291. Daehakhubo imitated and adopted expressions like 1 Byeon(change) and 1 Pyeon(edition), shown in the music written in the Annals of King Sejong, the foundation of Jongmyojeryeakbo music. Originally, 'Jeongdaeeop' recorded during the reign of King Sejong consisted of 6-Byeon and 13-Pyeon compositions, except Inlet and Outlet tunes. King Sejo, however, while rearranging this music into Jongmyo Shrine Mumuak music, reduced it to 9 tunes. And, when registering such arrangements in the musical scripts in the Annuals of King Sejo, he did not list the explanation of the titles as in the Annals of King Sejong. He just listed the nine tunes. In contrast to the musical scripts in the Annals of King Sejo, in Daeakhubo the details of Byeon and Pyeon under the nine tune titles are listed as in the Annals of King Sejong. This study revealed that Byeon and Pyeon expressed in Daeakhubo were the results of arbitrarily transcribing the different Byeon and Pyeon of 'Jeongdaeeop' and 'Balsang' in the Annals of King Sejong into the revised 'Jeongdaeeop' during the reign of King Sejo. Thus, under the titles of each score in 'Jeongdaeeop' of Daeakhubo are written the explanations of the muscial scores shown in both 'Jeongdaeeop' of the Annals of King Sejong and 'Balsang' of the Annals of King Sejong. Thus, the story of the son Ikjo is described even ahead of the story of the father Mokjo, and stories totally different from the original movements are described, creating overall errors. Such errors were presumably caused by powers that created the false musical script 'Sokakwonbo' during the Japanese colonial rule of Korea and disguised it as a traditional musical script.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.208-220
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• 2019

The seasonality of leaf fall has important implications for understanding the response of trees' phenology to climate change. In this study, we quantified the leaf fall pattern with a model to estimate the timing and speed of leaf litter according to species and considered the nutrient use strategy of canopy species. In the autumns of 2015 and 2016, leaf litter was collected periodically using 36 litter-traps from the deciduous forests in Gwangneung and sorted by species. The seasonal leaf fall pattern was estimated using the non-linear regression model of Dixon. Additionally, the resorption rate was calculated by analyzing the nitrogen concentration of the leaf litter at each collection time. The leaf litter generally began in early October and ended in mid-November depending on the species. At the peak time (T50) of leaf fall, on average, Carpinus laxiflora was first, and Quercus serrata was last. The rate of leaf fall was fastest (18.6 days) for Sorbus alnifolia in 2016 and slowest (40.8 days) for C. cordata in 2015. The nitrogen resorption rates at T50 were 0.45% for Q. serrata and 0.48% for C. laxiflora, and the resorption rate in 2015 with less precipitation was higher than in 2016. Since falling of leaf litter is affected by environmental factors such as temperature, precipitation, photoperiod, and $CO_2$ during the period attached foliage, the leaf fall pattern and nitrogen resorption differed year by year depending on the species. If we quantify the fall phenomena of deciduous trees and analyze them according to various conditions, we can predict whether the changes in leaf fall timing and speed due to climate change will prolong or shorten the growth period of trees. In addition, it may be possible to consider how this affects their nutrient use strategy.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.3
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• pp.374-383
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• 2010

Microwave radar can penetrate cloud cover regardless of weather conditions and can be used day and night. Especially a ground-based polarimetric scatterometer has advantages of monitoring crop conditions continuously with full polarization and different frequencies. Kim et al. (2009) have measured backscattering coefficients of paddy rice using L-, C-, X-band scatterometer system with full polarization and various angles during the rice growth period and have revealed the necessity of near-continuous automatic measurement to eliminate the difficulties, inaccuracy and sparseness of data acquisitions arising from manual operation of the system. In this study, we constructed an X-band automatic scatterometer system, analyzed scattering characteristics of paddy rice from X-band scatterometer data and estimated rice growth parameter using backscattering coefficients in X-band. The system was installed inside a shelter in an experimental paddy field at the National Academy of Agricultural Science (NAAS) before rice transplanting. The scatterometer system consists of X-band antennas, HP8720D vector network analyzer, RF cables and personal computer that controls frequency, polarization and data storage. This system using automatically measures fully-polarimetric backscattering coefficients of rice crop every 10 minutes. The backscattering coefficients were calculated from the measured data at a fixed incidence angle of $45^{\circ}$ and with full polarization (HH, VV, HV, VH) by applying the radar equation and compared with rice growth data such as plant height, stem number, fresh dry weight and Leaf Area Index (LAI) that were collected at the same time of each rice growth parameter. We examined the temporal behaviour of the backscattering coefficients of the rice crop at X-band during rice growth period. The HH-, VV-polarization backscattering coefficients steadily increased toward panicle initiation stage, thereafter decreased and again increased in early-September. We analyzed the relationships between backscattering coefficients in X-band and plant parameters and predicted the rice growth parameters using backscattering coefficients. It was confirmed that X-band is sensitive to grain maturity at near harvesting season.

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.191-201
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• 2011

Soybean has widely grown for its edible bean which has numerous uses. Microwave remote sensing has a great potential over the conventional remote sensing with the visible and infrared spectra due to its all-weather day-and-night imaging capabilities. In this investigation, a ground-based polarimetric scatterometer operating at multiple frequencies was used to continuously monitor the crop conditions of a soybean field. Polarimetric backscatter data at L, C, and X-bands were acquired every 10 minutes on the microwave observations at various soybean stages. The polarimetric scatterometer consists of a vector network analyzer, a microwave switch, radio frequency cables, power unit and a personal computer. The polarimetric scatterometer components were installed inside an air-conditioned shelter to maintain constant temperature and humidity during the data acquisition period. The backscattering coefficients were calculated from the measured data at incidence angle $40^{\circ}$ and full polarization (HH, VV, HV, VH) by applying the radar equation. The soybean growth data such as leaf area index (LAI), plant height, fresh and dry weight, vegetation water content and pod weight were measured periodically throughout the growth season. We measured the temporal variations of backscattering coefficients of the soybean crop at L, C, and X-bands during a soybean growth period. In the three bands, VV-polarized backscattering coefficients were higher than HH-polarized backscattering coefficients until mid-June, and thereafter HH-polarized backscattering coefficients were higher than VV-, HV-polarized back scattering coefficients. However, the cross-over stage (HH > VV) was different for each frequency: DOY 200 for L-band and DOY 210 for both C and X-bands. The temporal trend of the backscattering coefficients for all bands agreed with the soybean growth data such as LAI, dry weight and plant height; i.e., increased until about DOY 271 and decreased afterward. We plotted the relationship between the backscattering coefficients with three bands and soybean growth parameters. The growth parameters were highly correlated with HH-polarization at L-band (over r=0.92).

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.427-438
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• 2015

The effects of different feeding times, using a diet containing 800 ppm betaine, on production, blood profile, and the short-chain fatty acid (SCFA), was investigated using 240 Cherry Valley (Anas platyrhynchos) meat ducks exposed to a scorching heat wave. The animals were randomly assigned to four groups, each of which was replicated three times with twenty ducks per replicate. The experimental period was 42 days for each group. Four groups were assigned into C (heat wave control group without betaine), T1 (ad libitum group fed a diet containing 800 ppm betaine), T2 (diet-restricted group fed twice daily between 05:00-10:00 and 17:00-20:00, using a diet containing 800 ppm betaine), and T3 (night-restricted group, fed from 17:00-10:00, with a diet containing 800 ppm betaine). At 42 days, body weight increased in order of T2, T1, T3 compared to the heat wave control group although. However, these differences were not found between the groups of T1 and T3. The heat wave control group, provided an ad libitum diet without betaine (C), showed an elevated feed conversion ratio compared to the groups fed a diet containing betaine. However, these differences were not found between the groups of T1, T2 and T3. RBC and platelet profiles except for PLT and MPV showed statistically significant differences between study groups fed a diet containing betaine. T2 presented significantly higher blood electrolytes $Na^+$ and $Cl^-$ than the other groups. T2 also showed a blood gas level that was generally higher than the other groups. Total SCFA, acetic acid and propionic acid concentration has been the increasing trend in T2, but butyric acid, isobutyric acid and valeric acid concentration has been the decreasing trend in T2 compared to the other groups. It is concluded that the feeding-restricted group, fed two times daily between 05:00-10:00 and 17:00-20:00, with a diet containing 800 ppm betaine may improve growth performance in meat ducks exposed to a scorching heat wave.