• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.352-355
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• 2008

"Unmi" is a new japonica rice variety developed by the rice breeding team of Honam Agricultural Research Institute, NICS, RDA in 2007. This variety was developed from a across between Samcheonbyeo with lodging and cold tolerance and HR17870 derived from the cross of Iksan435 (Sobibyeo) and Sangju17 with resistance to diseases and good quality. This variety has about 110 days of growth duration from transplanting to harvesting in northern plain, northern and southern mid-mountainous areas of South Korea. It is about 68 cm in culm length and tolerant to lodging. In reaction to biotic and abiotic stresses, it shows moderate resistance to blast, and to bacterial blight pathogen races from $K_1$ to $K_3$, but susceptible to other major diseases and insect pests. The milled rice of "Unmi" is translucent and has relatively clear non-glutinous endosperm and medium short grain. It has about 17.3% amylose content and 6.3% of protein and similar palatability of cooked rice compared with Odaebyeo. The milled rice yield performance of this variety is about 5.16 MT/ha under the standard fertilizer level of the ordinary transplanting cultivation. "Unmi" would be adaptable for ordinary transplanting in the northern plain, northern and southern mid-mountainous area of South Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.264-273
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• 2020

'Ilpum', a Korean short-grain mid-late maturing rice cultivar, was developed in 1990, more than 30 years ago. Despite its age, it has been the most widely grown cultivar in the Gyeongbuk province of South Korea for more than 25 years, making it the most important rice cultivar for the people of the Gyeongbuk province. The aim of this study was to analyze the relationship between the rice yield of "Ilpum', the main rice cultivar in the Gyeongbuk province, and climate elements in the Daegu (southern plain area) and the Andong (inland mountainous area) regions in Gyeongbuk, South Korea. The rice yield over the past five years increased by about 13% and 24%, compared to that produced in the late 1990s in Daegu and the early 2000s in the Andong region, respectively. The number of panicles per hill and the grain ripening rate significantly affected rice yield in the 'Ilpum' cultivars in the Daegu region. The faster heading was a factor in the increase in 'Ilpum' rice yield in the Andong region. The air temperature has been rising and sunshine duration has been increasing from the late 1990s to present in both regions. Rice yield was evaluated to understand the effect of climate factors. The rice yields increased owing to the long sunshine duration during the grain-filling stage in both regions. In Andong, increasing the maximum temperature during the vegetative stage increased rice yield. Rising air temperature during the reproductive stage also increased rice yield. In particular, long sunshine hours throughout the whole rice growing period increased the rice yield of this cultivar in the Andong region.

• Korean Journal of Weed Science
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• v.17 no.3
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• pp.262-268
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• 1997

The experiment was carried out to obtain the basic information of weed control in lowland rice field in Gyeongbug province. The results were as follows : In weed distribution on life cycle, annual weed was occupied by 56.5% and perennials were 43.5%, respectively. In morphological distribution of weeds, grass weed was 25.2%, sedges was 12.3% and broad leaf weeds was 62.5%. In particular, weed occurrence of grass weed was much more increased than that of 1971 and 1981 year. Dominant weed species was Echinochloa crusgralli, Sagittaria trifolia, Eleocharis kuroguwai and Monochoria vaginalis in plain land, mid alpine area, and cold salty wind area. Dominant weeds was approximately similar occurrence in normal soil and poorly drained soil Gelds, but sandy soil field was not. Echinochloa crusgalli was dominant in hand transplanting and direct seeding on dry paddy field. Meanwhile, in machine transplanting, Sagittaria trifolia and Ludwigia prostrate were dominant, and occurrence of Echinochloa crusgalli was increased to delaying transplanting. As a result, major dominant weed was Echinochloa crusgalli, Sagittaria trifolia, Ludwigia prostrate, Eleocharis kuroguwai, and Monochoria vaginalis in terms of predominance.

• Korean Journal of Plant Resources
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• v.16 no.3
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• pp.212-217
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• 2003

This study was conducted to search for possible cultivation area of Rhodiola sachalinensis as well as to obtain the basic information of growth characteristics. One­year old nursery plants of Rhodiola sachalinensis were collected from Yonbyeon Hongkyungcheon development society in China This expriment was evaluted in three areas according to sea level such as plain region in Cheongwon(50m at sea level), mid­mountainous region in Jecheon(350m at sea level) mountainous region in Banyans(650m at sea level). The growth status Rhodiola sachalinensis showed wide range of variation in there areas. Plant height showed from 8.1cm to 15.8cm, number of branch showed from 3.1 eachs to 4.6 eachs and rate of withering showed from 76％ to 94％, respectively. It was increased rapidly at the early August caused by summer depression. Flowering period of Rhodiola sachalinensis was shown at around middle and late June, total duration of flowering showed from 12 to 13 days and flower colors were various as brown, dark purple, yellow green and brown red color.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.4
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• pp.222-233
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• 2022

The heading responses of rice varieties that originated from South Korea, North Korea, and northern China were examined under the temperature and day-length conditions of 13 major rice production areas in North Korea. Kenjiandao3 and Nongdae3 originated from China, Olbyeo1, Olbyeo2 and Sonbong9 from North Korea, and Joun from South Korea demonstrated the earliest heading stage depending on the regional environment. Out of 40 rice varieties, 34 reached the heading stage within the regional safe marginal heading date (SMHD) under Haeju and Sariwon environmental conditions, while 16 to 17 varieties reached the heading stage under Wonsan, Changjon, Supung, and Yongyon environmental conditions. Some middle and mid-late maturing varieties that originated from South Korea reached the heading stage within the SMHD under the temperature and day-length conditions of Kaesong, Haeju, Sariwon, Nampo, and Pyongyang that are located in the west-southern plain. The majority of early maturing varieties, but not the middle or mid-late ones, reached the heading stage within the SMHD under the environmental conditions of Singye, Anju, Kusong, and Sinuiju. Only a few early maturing varieties demonstrated the heading stage within the SMHD under Yongyon, Changjon, and Wonsan environments. The number of days to heading was highly positively correlated among all regions; however, it was not consistent among the rice varieties. The 40 rice varieties that had been tested were classified into seven groups according to their heading responses to the temperature and day-length variations of the 13 regional conditions at 65% similarity level in cluster analysis.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.284-293
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• 2020

Rice consumption in Korea has been decreasing as the eating habits of the Korean people have diversified with rapid economic growth. Recently, floury endosperm rice cultivars were developed to boost rice consumption and replace wheat flour consumption with rice flour, which is vulnerable to viviparity under wet weather during the grain-filling stage because of its loosely packed starch granule structures. To overcome this limitation, it is necessary to find a suitable rice transplanting date to produce high-quality rice flour by altering the heading ecology type and changing the cultivation time by region. We examined four floury endosperm rice cultivars (FERC) in the Cheongju (central plain area) and Boeun (mid-mountainous area) regions of Korea from 2017 to 2019. Of the FERCs, the mid-late maturing types (MMT) Seolgaeng (SG), Hangaru (HGR), and Shingil (SGL) exhibited high yield and yield components after transplanting May 30 in both regions; the early maturing type (EMT) Garumi 2 (GRM2) also exhibited high yield after transplanting June 20 in Cheongju. In addition, MMTs showed the same tendency as the characteristics shown in Cheongju when grown in the Boeun region, and EMT displayed high yield and yield components after transplanting June 10. The FERCs could easily present pre-harvest sprouting in the rainy season during the grain-filling stage after 20 days post-heading because the mean temperature and frequency of more three-day rainfalls have increased over the last 5 years from the previous annual averages. Viviparity of HGR and GRM2 decreased as the transplanting date was delayed, with decreases of 2.3%-4.6% in HGR and 11.9%-23.1% in GRM2 according to the region. SGL was generally resistant to viviparity because of the Tongil type. To minimize pre-harvest sprouting and produce high yield of rice flour in the Chungbuk province, the most suitable transplanting time was the end of May in MMT and the middle and end of June in EMT.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.103-113
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• 2001

This study presents Quaternary sedimentation pattern around Dok-Island volcanoes (Dok Island and Dok Seamount), based on analysis of high-resolution (chirp) echo characters. Echo facies If, showing sharp, continuous bottom echo without subbottom reflectors, is recorded mainly from the flat tops of the volcanoes. This facies indicates sands and gravels (re) deposited by shallow marine processes. Echo facies IIA in the basin floor and basal slopes of the volcanoes and Oki Bank is characterized by semi-prolonged bottom and several parallel subbottom echoes. This facies reflects hemipelagic settling with intermittent influences of turbidity currents in the slope areas. Echo facies IIC is recorded from acoustically-transparent debrite masses on the basal slopes of the volcanoes and Oki Bank. Echo facies IIIA is characterized by irregular hyperbolic echoes in the slope areas of the volcanoes. It suggests hard rock basement or irregular volcanic edifices. Echo facies IIIC shows regularly-overlapping hyperbolic bottom echoes. It is interpreted to represent rock-fall deposits (talus) accumulated in the mid-slope area. Echo characters and topography suggest that the tops of Dok-Island volcanoes were flattened and lowered by shallow-marine erosional processes. The eroded sediments were transported to and deposited in the base of slope and basin plain mainly by debris flows and turbidity currents along submarine canyons and valleys.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.4 s.44
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• pp.29-42
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• 2005

Total 350 borehole profiles were selected from the database of borehole logs in Seoul, for the site-specific seismic evaluation at two 4km${\times}$4km plain areas. Equivalent-linear site response analyses for the selected 350 sites were conducted based on shear wave velocity (Vs) Profiles, which were determined from the N-Vs correlation established using borehole seismic testing results in the inland areas of Korea. Most sites were categorized as site classes C and D based on the mean Vs to 30 m in depth (Vs30) ranging from 250 to 550 m/s. The she periods of the plains in Seoul ranging between 0.1 and 0.4 sec were significantly lower than those of the western US, from which the site coefficients in Korea were derived. For plains in Seoul, the site coefficients, Fa's and Fv's specified in the Korean seismic design guide, underestimate the ground motion in short-period (0.1-0.5 sec) band and overestimate the ground motion in mid-period (0.4-2.0 sec) band, respectively, because ol the differences in the geotechnical conditions between Seoul and the western US, although the Fa's in several sites overestimate the motion due to the base Isolation effect resulted from the soft layer in soil deposit.

• Korean Journal of Weed Science
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• v.10 no.2
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• pp.83-92
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• 1990

Experiment was conducted to establish the weed control system on the paddy fields by investigating species, period and amount of weeds in Gangwon province. Four locations were selected for these experiments : West plain area, Chunchon(74m above the sea level), mid-mountainous area, Hongchon(300 m), high alpine area, Hoengsong(450m), and east sea area, Myungju(14m). Weed emergence was investigated 6 times from 10 days after transplanting to 60 days with 10 days interval. From the experiments stated above, the results were summarized as follows ; The identity of weed species was small in grass family, but broad-leaf family was numerous. Also the dominant weed species was generally the perenial weeds. The weed emergence was initiated from 10 days after translanting. The amounts of weed counted the most in Chunchon. A large number of weeds were emerged between 30-60 days after transplanting in Chunchon and between 40-60 days after transplanting in Hongchon and Hoengsong. Among agronomic characteristics affected by weed emergence during rice development, plant height was decreased by 2~4cm, panicle number by 1.3~2.9, spikelet by 3.7~7.5, ripening rates 3.3~6.5%, and milled yield by 12~17%, respectively.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.547-551
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• 2009

A new commercial rice variety "Chilbo" is a japonica rice (Oryza sativa L.) with resistance to rice stripe virus and high grain quality. It was developed by the rice breeding team of Yeongdeog Substation, NICS, RDA in 2007. This variety was derived from a cross between "Yeongdeog 26" with wind tolerance and lodging resistance and "Koshihikari" with good grain quality. A promising line, YR21324-119-3-2 was selected by a pedigree breeding method and designated as "Yeongdeog 44" in 2004. Regional adaptation yield trials were carried out at eleven locations from 2005 to 2007. As a result, "Yeongdeog 44" was released as a high yielding rice variety with high grain qualilty and virus resistance with the name of "Chilbo". It is short 76cm in culm length and has medium-late growth duration. This variety is resistant to stripe virus and middle resistant to leaf blast disease. It is also tolerant to cold, dried wind. Milled rice kernel of "Chilbo" is translucent, clear in chalkiness. Panel test proved that and it has good eating quality. Head rice ratio of Chilbo is high compared to the check variety, Hwaseongbyeo. Yield potential of "Chilbo" in milled rice is about 5.57MT/ha at ordinary fertilizer level of local adaptability test. This variety would be adaptable to Yeongnam plain, south & east-south coastal, south mid-mountainous, middle plain area of Korean peninsula.