• Management Science and Financial Engineering
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• 제18권2호
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• pp.5-11
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• 2012

In this paper, stochastic scheduling problems are considered when processing times and due dates follow arbitrary distributions and due dates are either common or exchangeable. For maximizing the expected number of early jobs, two policies, one, based on pairwise comparisons of the processing times, and the other, based on survivabilities, are introduced. In addition, it is shown that the former guarantees optimal solutions when the processing times and due dates are deterministic and that the latter guarantees optimal solutions when the due dates follow exponential distributions. Then a new approach, exploiting the two policies, is proposed and analyzed which turns out to give better job sequences in many situations. In fact, the new approach guarantees optimal solutions both when the processing times and due dates are deterministic and when the due dates follow exponential distributions.

• 한국초지조사료학회지
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• 제33권3호
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• pp.185-192
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• 2013

This study was carried out to investigate the influence of the seeding dates on the yield and feed value in cultivating Italian rye grass on paddy soil. The field experiment was designed in a randomized block design of 3 repetitions with seeding dates of Oct. 19 (T1), Oct. 26 (T2), Nov. 2 (T3), Nov. 9 (T4), and Nov. 16 (T5) treatments. Plant length, fresh yield, dry matter yield and TDN yield were increased with early seeding dates (p<0.05). Crude protein, Crude fat and crude ash were increased with early seeding dates (p<0.05). On the other hand, NDF, ADF and Crude fiber were decreased with early seeding dates (p<0.05). Total mineral contents were higher in the order of T4 > T3 > T5 > T1 > T2 (p<0.05). The total composition amino acid content was decreased significantly (p<0.05) as the seeding dates delayed. Total free sugar content was highest in T1, whereas the lowest in T5 treatment (p<0.05). Nutrition yields (crude protein, crude fat, amino acid and free sugar) were increased significantly with early seeding dates (p<0.05). The above result indicated that it is favorable to seed soon after rice harvest to increase dry matter yield and nutrition yield of Italian ryegrass in the midlands.

• 한국작물학회지
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• 제51권2호
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• pp.113-117
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• 2006

To identity the effect of sowing dates on flowering and maturity of sesame, some agronomic traits including days to flowering and days to maturity were investigated under five different sowing dates. Plant height, days to flowering, days to maturity, days from flowering to maturity and number of capsules per plant were showed significantly different by years, sowing dates and varieties. Interaction between sowing dates and varieties affected to days to flowering, days to maturity, days from flowering to maturity and number of capsules per plant. Plant height, days to flowering and days to maturity decreased significantly as sowing dates were delayed, but number of capsules and seed weight per plant showed highest at the sowing date of May 10. At the regression analysis of shortness degree of growth period by the response of days to flowering and days to maturity under different sowing dates, sesame varieties with earlier flowering habit were much less affected by day length rather than ones with later flowering habit. $R^2$ and gradient value on the days to maturity regression graph were smaller indicating that maturity was much less sensitivity than flowering to the change of day length and temperature in the move of sowing dates. Therefore, it would be concluded that early maturity sesame varieties have higher potential adaptability to various sesame cropping systems in view of their less sensitivity to day length changes under different sowing dates.

• 한국작물학회지
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• 제26권4호
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• pp.337-343
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• 1981

단교잡종 옥수수민 수원19호를 3월 26일부터 7월 9일까지 15일 간격으로 8회 파종하여 파종기가 종실 및 싸일레이지 수량과 생육기간에 미치는 영향을 보면 다음과 같다. 1. 파종기가 빠를수록 파종에서 출현까지 일수가 길어지나 출현율은 65%인 3월 26일의 극조식을 제외하면 4월 9일 이후의 파종구는 출현율이 80% 이상이었다. 2. 종실수량은 4월 25일까지는 파종기간에 차이가 없었으로 그 이후는 파종이 지연될수록 자수를 발달시키지 못하는 포기의 증가와 수당잎수의 감소로 수량이 감소하였다. 3. 건물중으로 표시한 싸일레이지 수량은 5월10일 파종까지는 차이가 없었으나 그 이후는 파종이 지연될수록 수량, 건물비율, 종실중/전건물중 비율이 현저히 감소하였다. 4. 파종에서 출사까지 일수는 파종류가 지연됨에 따라 108 일에서 52일까지 감소하였으나 유효적산 온도로 표시하면 파종기에 관계없이 비슷하였으며 평균 815$^{\circ}C$이었다. 5. 종실 및 싸일레이지 생산을 목표로 할 때 등숙기간은 다수확을 위한 파종한계기 이내에 파종하면 각각 44 및 40~42일 이었으나 다수확을 위한 파종만한기 이후에 파종하면 성숙까지 일수는 헌저히 증가되었다. 그러나 유효적산온도로 표시하면 파종에 상관없이 종실용은 평균 697$^{\circ}C$ 싸일레이지용은 651$^{\circ}C$이었다.

• 한국제4기학회지
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• 제15권2호
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• pp.63-73
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• 2001

현재까지 모두 29개의 탄소연대가 구석기유적과 관련하여 얻어졌다. 그런데 소로리 유적의 피트층의 연대를 제외한다면 그 수는 20개를 밑돌고 있다. 탄소연대측정치의 분포로 볼 때, 후기구석기시대의 시작은 4 만년 전의 연대에 접근할 수 있는 것으로 보이지만 아직도 연대측정치의 신뢰도의 확보가 중요하고 보다 많은 연대측정치가 누적되어야 할 것으로 생각된다. 세석인공작의 상한과 하한의 연대에 대해서도 현재까지 몇 건의 중요한 연대치로서 대체로 2 만년이 넘을 것으로 보인다. 그런데 후기구석기의 특성상 상당히 세밀한 연대치들이 필요할 것으로 판단되는데 아직도 연대치의 수효가 그리 많지 않아서 정확한 연대를 단언하기가 어렵다. 앞으로 석기공작들의 변화에 대한 분석과 함께 다른 방법의 연대측정치들과 비교하고 또한 많은 수의 탄소연대측정이 있어야 보다 정확한 편년을 기할 수 있을 것으로 판단된다. 한가지 특기할 것은 몇 유적에서 보이는 아이라화산재의 연대(약 24,000 BP)와 탄소연대와 정확하게 맞지 않는 경우들이 있는데 크게는 이해할 수 있는 범주에 들지만 앞으로 유적의 형성과정에 대한 세심한 배려가 결론의 신뢰도를 높일 것으로 생각된다.

• Journal of Animal Science and Technology
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• 제61권5호
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• pp.278-284
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• 2019

This study was carried out to investigate the effects of seeding dates on the yield and feed value of whole-crop barley cultivated in paddy soil. The field experiment was conceived as a randomized block design performed in triplicate with seeding dates of Oct. 19 (T1 as treatment 1), Oct. 26 (T2 as treatment 2), Nov. 2 (T3 as treatment 3), Nov. 9 (T4 as treatment 4), and Nov. 16 (T5 as treatment 5) as treatments. The barley grown in all treatments was harvested on May 21 of the following year. Plant length, fresh yield, dry matter yield, and total digestible nutrient (TDN) yield were higher (p < 0.05) in barley with early seeding dates, whereas crude protein and ether extract were higher (p < 0.05) with late seeding dates. Crude fiber and neutral detergent fiber were highest in the T3 treatment and lowest in the T1 treatment. There was no significant difference between acid detergent fiber and TDN among the different seeding dates. Total mineral contents were higher in the order T1 > T2 > T3 > T4 > T5 (p < 0.05), whereas the total amino acid content increased significantly (p < 0.05) with a delay in seeding date. Free sugar contents (fructose, glucose, and sucrose) were higher with early seeding dates (p < 0.05). Collectively, the results obtained in this study indicate that it is favorable to seed soon after harvesting rice to increase dry matter and TDN yields and mineral and free sugar contents of whole-crop barley in the midlands of Korea.

• 대한원격탐사학회지
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• 제38권1호
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• pp.57-72
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• 2022

In this paper, we aimed to examine the flowering dates of cherry blossom and the peak dates of maple leaves in South Korea, by the combination of temperature observation data from ASOS (Automated Surface Observing System) and NDVI (Normalized Difference Vegetation Index) from MODIS (Moderate Resolution Imaging Spectroradiometer). The more recent years, the faster the flowering dates and the slower the peak dates. This is because of the impacts of climate change with the increase of air temperature in South Korea. By reflecting the climate change, our statistical models could reasonably predict the plant phenology with the CC (Correlation Coefficient) of 0.870 and the MAE (Mean Absolute Error) of 3.3 days for the flowering dates of cherry blossom, and the CC of 0.805 and the MAE of 3.8 for the peak dates of maple leaves. We could suppose a linear relationship between the plant phenology DOY (day of year) and the environmental factors like temperature and NDVI, which should be inspected in more detail. We found that the flowering date of cherry blossom was closely related to the monthly mean temperature of February and March, and the peak date of maple leaves was much associated with the accumulated temperature. Amore sophisticated future work will be required to examine the plant phenology using higher-resolution satellite images and additional meteorological variables like the diurnal temperature range sensitive to plant phenology. Using meteorological grid can help produce the spatially continuous raster maps for plant phenology.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.59-59
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• 2022

The transplanting date of rice affects grain yield and quality, and it is changed by the environment during cultivation. Thus, it is important to provide the optimal transplanting dates for rice growers under global warming environment. In this study, transplanting date experiments with thirty-day-old seedlings of three cultivars (early, mid, and mid-late maturity) were conducted at the National Institute of Crop Science in Suwon from 2018 to 2021 to determine the optimal transplanting dates for and quantify the effect of planting dates on yield and quality. Transplanting date was strongly associated with culitvar across every year. Clear relationships between transplanting date and head rice yield in early and mid-late maturing rice varieties were observed, and the highest head rice yields were observed during transplantings in mid and late June for early maturing cultivar and mid June for mid-late maturing cultivar. It is obvious that the optimal rice transplanting dates have been shifted and are better later than the optimal transplanting dates in 2002-2004. Days to heading was also strongly associated with the transplanting date and cultivar with 89% of the variation explained. Days to heading was reduced in the later transplanting dates. Grain yield was strongly associate with biomass production during ripening(R²=0.85), however translocated biomass from leaf and stem showed little association with grain yield. The results from this study reconfirmed the importance of shifting optimal transplanting dates to maximize head rice yield for the Mid-plain area in South Korea.

• 한국자원식물학회지
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• 제25권6호
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• pp.700-706
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• 2012

Influences of different seeding dates on growth, seed yield, fatty acid composition and oil content were investigated in flax plants for two years. The results indicated that plant height in early seeding date was higher than that of delayed seeding dates during first season. Furthermore, seeding date also significantly affected the ripened seed rate and the rate increased with the delay in seeding date in first season. Seed yield in the first crop season was significantly higher than the second crop season. Palmitic acid showed variation in different seeding dates. Contrarily, stearic acid was stable and did not changed by different seeding dates. Linolenic acid was found in highest amount in all seeding dates consecutively in two cropping years. Highest oil content was recovered from the seeds of flax sown at 29 Apr. and May 9 in first and second cropping year respectively.

• Journal of Ecology and Environment
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• 제31권2호
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• pp.153-159
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• 2008

The timing of the canopy phenology onset (CPO hereafter) indicates the initiation of the growing season, with rapid increases in exchange rates of carbon dioxide and water vapor between vegetation and atmosphere. The CPO is regarded as a potential indicator of ecosystem responses to global warming, but the CPO shows considerable spatial variation depending on the species composition and local temperature regime. at a given geographic location. In this study, we evaluated the utility of satellite observation data for detection of the timing of the CPO. Leaf area indices (LAI) obtained from the Moderate Resolution Imaging Spectrora-diometer (MODIS) were utilized to detect and map the onset dates from 2001 to 2006. The reliability of MODIS-based onset dates was evaluated with ground measured cherry blossom flowering data from national weather stations. The MODIS onset dates preceded the observed flowering dates by 8 days and were linearly related with a correlation coefficient of 0.58 (p < 0.05). In spite of the coarse spatial (1 km) and temporal (8 days) resolutions of MODIS LAI, the MODIS-based onset dates showed reasonable ability to predict flowering dates.