• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.1
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• pp.63-71
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• 2020

The purpose of this study was to analyze the growth characteristics of perilla according to the materials of the seedbed for the development of seedling plug technology suitable for the mechanical transplantation of perilla. Perilla (Perilla frutescens var. japonica Hara) cultivars Deulsaem and Sodam were used in this experiment. The composition ratios of 170 products from 16 companies published in the 'Korean Association of Seedbed Media' homepage were compared according to usage and type, and 11 products that corresponded to the average were selected. The seedbed was classified according to the seedbed for paddy rice as light-weight, semi-weight, and weight, and based on the seedbed for horticulture, as light-weight and ultra-light. The seedlings were placed in 72-cell (semi-automatic), 128-cell (automatic) and 220-cell (automatic) plug trays. We selected 2 light-weight seedbeds of paddy rice and 2 light-weight seedbeds of horticultural products with the highest plant growth. We analyzed plant height and mat formation of the perilla roots. Results showed that the perilla height and mat formation were the best in light-weight seedbeds of paddy rice (product R1). Therefore, light-weight seedbeds of rice (product R1) were suitable for perilla plant transplantation. The estimated major components were vermiculite 41.0%, cocopeat 31.0%, peat moss 5.7%, and red-yellow soil 20.0%. The mechanical transplantation of perilla significantly boosts plant growth and reduces sowing and thinning efforts. However, continuous evaluation of newly introduced, commercial seedbeds is needed.

• Progress in Medical Physics
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• v.17 no.1
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• pp.1-5
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• 2006

A parallel plate detector containing PTFE films in FEP film for relative dosimetry was designed to measure the response of detectors to S and 10 MV X-rays from a medical linear accelerator through different thicknesses of lead. The dielectric materials were 100 m thick. The set-up conditions for measurements with this detector were as follows: SSD=100 cm the test detector was at a depth of 5 cm and the reference chamber was at a depth of 10 cm from the phantom surface for 6 and 10 MV X-rays. Lead blocks were designed to cover the irradiated field. They were added to the tray to increase thickness sequentially. We found that the detector response decreased exponentially with the thickness of lead added. The linear attenuation coefficients of the test detector and reference chamber were 0.1414 and 0.541, respectively, for 6 MV X-rays and 0.1358 and 0.5279 for 10 MV X-rays. The test detector response was greater than that of the reference chamber. The response function was calculated from the measured values of the test detector and reference chamber using optimization. These optimized constants for the detector response function were independent of theenergy. As a result of optimizing the response function between detectors, the use of a relative dosimeter was validated, because the response of the test detector was 1% for 6 MV X-rays and 4% for 10 MV X-rays.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.286-292
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• 2019

This study aimed to investigate the suitable of layer on growth of six baby leaf vegetables using existing facilities and equipment in rice seedling nursery. Three kinds of Lactuca(lettuce 'Jinppallola' and 'Romain white', and indian lettuce), two of Brassica(tatsoi and red tatsoi) and amaranth were used as the materials. After sowing, the rice seedling tray was placed in multi bench system($L120{\times}W60{\times}H195cm$, 10th floor), which were low(1st) layer above 15cm, middle(4th) layer above 115cm and high(7th) layer above 175cm apart from ground. Irrigation was sprayed 2~3 times a day using a automatic irrigation system. The growth characteristics and leaf color were investigated when leaf vegetables were reached the optimum size(within 10cm of plant height). During the culture periods(29th Jun.~31th Jul. 2017), daytime average temperature was $27.4{\sim}28.3^{\circ}C$ regardless of layers but solar irradiance was higher in the high-layer than low and middle-layer of 37% and 22%, respectively. The leaf length, leaf width and number of leaves in middle and high-layer have a tendency to increase but, fresh weight was different according to the layer. When the correlation between accumulation radiation and growth was analyzed, all of growth factor of Amaranth showed a high correlation and other cultivars showed correlation with each growth factors. As a result, It is suitable that amaranth and red tatsoi for high-layer, Indian lettuce and tatsoi for middle and high-layer and 'Romain white' for middle-layer. The growth of red lettuce 'Jinppallola' was good at low layer, but leaf color expression was poor. So the high layer is suitable for 'Jinppallola'.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.3
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• pp.190-200
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• 2021

The heading response of rice varieties, originated from South Korea, North Korea, and northern China, was examined under the temperature and day-length conditions of 10 low-temperature regions in North Korea. When 30-day-old broadcast tray-raised seedlings (BS) were used, only one or a few varieties reached the heading stage within the safe marginal heading date (SMHD) under the Hamhung, Pyonggang, Huichon, and Kanggye conditions. In the Yangdok and Sinpo environments, no varieties reached heading until SMHD. The South Korean varieties that reached the heading stage between SMHD and late marginal heading date (LMHD) were Jinbuol, Baegilmi, Joun, Jopum, Jinok, Jopyeong, Sanhomi, and Odae for the Hamhung, Pyonggang, Huichon, and Kanggye; Joun for Sinpo; and none for Yangdok, Kimchaek, Sonbong, and Chunggang environments. The number of days to heading (DTH) was positively correlated among all 10 regions. Reduced DTH in the 30-day-old pot tray-raised seedlings (PS), compared to BS, was not consistent with varieties and regions. Reduced DTH in PS, compared to BS, was the largest in Jinok and Sonbong9 among the South and North Korean varieties, respectively, whereas it was small in the northern Chinese varieties. The South Korean varieties that headed until SMHD in PS were Jinok for the Hamhung, Pyonggang, Yangdok, Sinpo, and Kanggye environments; and Jinbuol, Jopum, and Jinok for the Huichon condition. In the Kimchaek and Chunggang conditions, Jinok reached the heading stage within LMHD. With the use of PS for some responsive varieties such as Jinok, varietal adaptability could be improved to the conditions of low-temperature regions in North Korea. None of the PS or BS among the tested varieties reached the heading stage until LMHD for the Chongjin and Sonbong conditions.

• Journal of the Korean Society of International Agriculture
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• v.23 no.5
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• pp.520-530
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• 2011

This study was carried out to evaluate the possibility of rice double cropping in Korea by assessing the growth and yield performance of rice cultivars transplanted at the extremely-early date. When the transplanted rice seedling was exposed to low temperature below 0℃, the survival rate decreased drastically. However, short exposure to below 0℃ one or two times did not damage transplanted rice seedling so severely. Thus, the earliest transplanting in spring would be possible when minimum temperature rises above 0℃. Compared with the conventional seedling nursery tray (CSNT), seedling rearing with the potted nursery tray was more effective for increasing leaf age and seedling dry weight during nursery period. In the first rice cropping, rice cultivation with seedlings reared in PSNT showed shorter growth duration and cumulative temperature from transplanting to heading than that with seedlings reared in CSNT. The earliest heading date on July 4 in Jinbuolbyeo was earlier by two to three days than that of Dunaebyeo. If rice has not exposed to cold damage, the earliest heading date of Jinbujolbyeo can advance to June 30 or July 1. In this case, rice harvest would be possible on August 5, enabling the rice transplanting of the second rice cropping before August 10. At transplanting time with low temperature damage rice yield were less than 400 kg/10a while rice yield exceeded 400 kg/10a at transplanting time without low temperature damage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.246-261
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• 2023

We investigated critical temperature for early marginal transplanting (CT-EMT) of the contemporary japonica rice varieties in Korea through the field, pot seedling tray, and the phytotron experiments during 2020 to 2023. The lowest mean temperature for 10 days from transplanting (MT-10DFT) that resulted in earlier heading date was 12.4℃ and the highest MT-10DFT that did not show the earlier heading date was 12.0℃ in the field study when the MT-10DFT varied by changing transplanting date. The lowest MT-10DFT that induced the increased biomass but not the earlier heading date was 11.6℃ and the highest MT-10DFT that showed neither the increased biomass nor the earlier heading date was 11.4℃. Compared to the 10-day later transplanting, the dates of the first root development, initiation of the chlorophyll recovery, and the first tiller development were earlier when the MT-10DFT was 9.1℃ or higher, 10.5℃ or higher, and 11.6℃ or higher, respectively, in the pot seedling tray and field experiments. The earliness of the first tiller development was a practical index for the estimation of CT-EMT during the early growth stage of rice. The response of transplanted rice to temperature treatments with the diurnal change of 10℃ in the phytotron study was similar to that shown in the field study. The data shown for constant temperature without a diurnal change revealed that the extent of positive effects of high temperature at day-time was greater than the extent of negative effects of low temperature at night-time on the early growth of transplanted rice. It was concluded that the critical MT-10DFT for early marginal transplanting of japonica rice in the temperate environments was between 11.4 to 11.6℃ based on the plant growth and between 12.0 to 12.4℃ based on the plant development.

• Korean Journal of Food Science and Technology
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• v.40 no.4
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• pp.460-465
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• 2008

This study examined the effect of head formation on the quality maintenance of minimally processed lettuce (Lactuca sativa L.) samples. The fresh-cut lettuce samples were packed in $20{\times}15{\times}5$ cm polypropylene+polyethylene terephthalate tray, and were then stored at $4^{circ}C$ for up to 8 days. According to the results, the sample with 100% head formation had lower sugar, minerals (Ca, Na, Fe, Mg, K), and chlorophyll contents compared to the sample with 70% head formation. The 70% head formed lettuce had higher vitamin C content at 3.30 mg/100 g, whereas the 85% and 100% formed samples had lower levels of 2.61 and 2.10 mg/100 g, respectively. The polyphenol oxidase (PPO) activity of the 70% formed lettuce was 240 unit/g, while the 100% formed sample had almost 2-fold higher activity. However, the 100% formed lettuce had greater firmness than all other samples. Overall, among the fresh-cut lettuces, the sample with 70% head formation showed more positive effects in terms of quality maintenance.

• Horticultural Science & Technology
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• v.19 no.4
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• pp.483-487
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• 2001

This study was carried out to investigate the role of attached leaflet on rooting and growth by one nodal cutting in tomato. As cutting sources 4 to 6 nodes could be obtained from one nursery seedling. Medium for cutting was a mixture with perlite plus peat moss (1 : 1, v/v), and each plug capacity was 30mL in the 72 cells-plug tray. Plant height and the number of leaves were significantly increased by attached leaflet cutting in 'Pepe' and 'Coco' cherry tomato. Dry weights of top and root were increased as much as 3 to 15 times in the cutting attached leaflet. Rooting percentage was 93.5% in one node cutting and 86% in the cutting with hypocotyl node part. At 20 to 24 days after nodal cutting, healthy nursery plant could be produced to transplant in field. The nursery plants by nodal cutting (NPNC) showed more fibrous roots and less tap roots than that of seedling. In terms of rooting pattern, NPNC rooted at the whole ground stem part, while rooting of seedling occurred at basal part of hypocotyl.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.8
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• pp.1157-1163
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• 2014

This study was conducted to observe the effects of gas composition in modified atmosphere packaging (MAP) on the shelf-life of Longissimus dorsi of Korean Native Black Pigs-Duroc Crossbred ($KNP{\times}D$) during refrigerated storage. Muscle sample was obtained from the left side of carcass of seven months old of $KNP{\times}D$ barrow. The sample was sliced into 1 cm in thickness, placed on trays (two slices/tray) and filled with different gas composition, i.e. 0:20:80/$O_2:CO_2:N_2$ (MAP1), 30:20:50/$O_2:CO_2:N_2$ (MAP2) and 70:20:10/$O_2:CO_2:N_2$ (MAP3). Other slices of sample were vacuum packed (VP) as a control. All packs were stored at $5{\pm}1^{\circ}C$. At 12 d of storage, pH value of MAP2 and MAP3 were higher (p<0.05) than that of MAP1 and pH value of MAP1 was higher (p<0.05) than that of VP. At 6 d of storage, redness ($a^*$) value of MAP2 and MAP3 were higher (p<0.05) than that of VP and MAP1 and, at 9 and 12 d of storage, redness value of MAP3 was higher (p<0.05) than that of VP, MAP1, and MAP2. At 3, 6, 9, and 12 d of storage, the 2- thiobarbituric acid reactive substances (TBARS) value of MAP3 was higher than that of MAP2 and TBARS value of MAP2 was higher than that of VP and MAP1. At 3, 6, 9, and 12 d of storage, volatile basic nitrogen values of MAP2 and MAP3 were higher (p<0.05) than those of VP and MAP1. At 3 d of storage, total aerobic plate counts of MAP2 and MAP3 were higher (p<0.05) than those of VP and MAP1 and, at 6 d of storage, total aerobic plate counts of MAP3 was higher (p<0.05) than that of MAP1 and MAP2. However, there was no significant different total aerobic plate count among MAP1, MAP2, and MAP3 at 9 and 12 d of storage. There was no significant different total anaerobic plate count among MAP1, MAP2, and MAP3 during storage. It is concluded that the MAP containing 30:20:50/$O_2:CO_2:N_2$ gas composition (MAP2) might be ideal for better meat quality for $KNP{\times}D$ meat.

• Food Science and Preservation
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• v.20 no.6
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• pp.775-783
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• 2013

Changes in the various quality characteristics of hamburg steak depending on the packaging methods were investigated during storage at $5{\pm}1^{\circ}C$ for up to 15 days. Three packaging treatments including vacuum packaging (VAP), air-containing packaging (AC), and oxygen scavenger packaging (OS) were applied in this experiment. The initial total aerobe bacteria counts were identical at 2.3 log CFU/g in all treatments, but the growth rate of total aerobe bacteria in the AC samples was significantly faster than the VAP and OS samples during storage. The changes in the TBA and VBN values over the storage time showed that lipid oxidation and protein spoilage developed fastest in the AC sample, followed by OS and then VAP samples. The instrumental color and texture profiles were not significantly differ between treatments during storage (p>0.05). After 12 days of storage at $5^{\circ}C$, evaluation of the samples' sensory attributes showed that the AC samples had become unmarketable with a score of less than 5.0 points for all sensory properties, whereas the VAP and OS samples were still marketable.