• Title/Summary/Keyword: development delay

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A Study on Development of Guideline on Writing Technical Document for Electrical Medical Devices: Dental X-ray Equipment (치과용엑스선장치의 기술문서 작성을 위한 가이드라인 개발 연구)

  • Lee, Seung-Youl;Kim, Jae-Ryang;Lee, Jun-Ho;Park, Chang-Won
    • Journal of radiological science and technology
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    • v.39 no.4
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    • pp.651-660
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    • 2016
  • Due to recent population aging, the number of check-up for senior citizens has increased steadily. According to this trend, the market size of dental X-ray equipment and the number of approval and review for these devices have simultaneously increased. The technical document of medical device is required for approval and review for medical device, and medical device companies needs to have work comprehension and expertise, as the document needs to include the overall contents such as performances, test criteria, etc.. Yet, since most of domestic manufacturers or importers of medical devices are small businesses, it is difficult for them to recruit professional manpower for approval of medical devices, and submission of inaccurate technical documents has increased. These problems lead to delay of the approval process and to difficulties in quick entering into the market. Especially, the Ministry of Food and Drug safety (MFDS) standards of a dental extra-oral X-ray equipment, a dental intra-oral X-ray equipment, an arm-type computed tomography, and a portable X-ray system have been recently enacted or not. this guideline of dental X-ray equipment adjusting revised standards was developed to help relative companies and reviewers. For this study, first, the methods to write technical document have been reviewed with revised international and domestic regulations and system. Second, the domestic and foreign market status of each item has been surveyed and analyzed. Third, the contents of technical documents already approved by MFDS have been analyzed to select the correct example, test items, criteria, and methods. Finally, the guideline has been developed based on international and domestic regulation, through close review of a consultative body composed of academic, industrial, research institute and government experts.

The vacuolar processing enzyme (VPE) mutation suppresses an HR-like cell death induced by the double knockout mutant of vacuolar Ca2+-ATPases in Arabidopsis (애기장대에서 두 액포막 칼슘펌프 돌연변이에 의하여 유도되는 세포사멸 표현형의 액포수식효소(VPE) 돌연변이에 의한 억제)

  • Park, Hyeong-Cheol;Lee, Sang-Min;Kim, Ho-Soo;Chung, Woo-Sik
    • Journal of Plant Biotechnology
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    • v.38 no.2
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    • pp.169-175
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    • 2011
  • Calcium ($Ca^{2+}$) signals have been implicated in regulating plant development and responses to the environmental stresses including a programmed cell death pathway. In animals and plants, cytosolic $Ca^{2+}$ signals have been involved in the activation of programmed cell death (PCD). Recently, we reported that disruption of Arabidopsis vacuolar $\b{A}$utoinhibited $\underline{C}a^{2+}$-$\b{A}$TPases (ACAs), ACA4 and ACA11, resulted in the activation of a salicylic acid-dependent programmed cell death pathway. Although extensive studies have revealed various components of a PCD in plants, executors to directly induce PCD are well unknown. Here, we provide that the vacuolar processing enzymes (VPEs) are involved in a PCD induced by the double knockout mutant of vacuolar $Ca^{2+}$-ATPases in Arabidopsis. The gene expression of VPE was rapidly up-regulated and the enzyme activity of VPE was increased in the double mutant plants. We also generated aca4/aca11/avpe, aca4/aca11/${\gamma}$vpe and aca4/aca11/avpe/${\gamma}$vpe mutant plants. Although cell death phenotype of the double mutant plants was not completely disappeared in the triple and quadruple mutant plants, the triple and quadruple mutant plants showed to significantly delay cell death phenotype of the double mutant plants. These results suggest that the VPE is involved in the HR-like cell death in the double mutant of vacuolar $Ca^{2+}$-ATPases in Arabidopsis.

Liability of Air Carrier and its Legislative Problems in China : Some proposals for its Amendments (중국 항공운송법의 현황 및 주요내용과 앞으로의 전망 : 항공운송인의 책임을 중심으로)

  • Li, Hua
    • The Korean Journal of Air & Space Law and Policy
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    • v.26 no.1
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    • pp.147-176
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    • 2011
  • China is experiencing rapid economic development and the volume of air passengers and cargo transportation has increased significantly in recent years. To the contray, the regulations on liability of air carrier in china fall behind and are not sufficiently applicable in disputes. Their lack of sufficient protection for air passenger's interests became obstructive factor for further developments of Chinese air transportation industry. The legal system of air carrier's liability mainly consists of the contents as followed. The liability period, the scope of liability, amount of compensation for damage, limitation of liability, liability exemption of air carrier, jurisdiction, limitation of action, applicable law etc. Laws and rules concerning these issues are regulated in Civil Aviation Law and regulations published by Civil Aviation Administration of China. This article described the main contents of air carrier's liability and examined the legislative problems in their applications in real cases. In order to solve the legal problems on the air carrier's liability and disputes between wrongdoers and survivors etc, it is necessary and desirable for china to amend revelvant provisions. One of my proposals is to raise the amount of compensation limitation for damage. And I also would like to suggest that Civil Aviation Law should treat international and domestic transportation equally on the limitation of compensation for air carrier's liability. China has also acceded to the Montreal Convention of 1999 on July 31, 2005. This is an effort to make the law of air carriage unified worldwide through various international conventions to achieve conformity between rules of international air carriage and that of Chinese domestic aircarriage. Furthermore, there should be additional detailed implementation rules for air carrier to assume liability for the losses to passengers, baggage or cargoes caused by delays in the air transport. Significant clarifications are also needed for provisions concerning whether and how air carrier assume liability for moral damage caused by accident.

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A Very Early-Maturing, Cold Tolerant and High Quality japonica Rice Variety 'Hanseol' (극조숙 고품질 내냉성 벼 신품종 '한설')

  • Lee, Jeong-Heui;Shin, Young-Seop;Jeong, O-Young;Kim, Myeong-Ki;Kim, Yeon-Gyu;Kim, Hong-Yeol;Lee, Jeom-Ho;Lee, Jeong-Il;Cho, Young-Chan;Jeon, Yong-Hee;Choi, Yong-Hwan;Yang, Chang-Ihn;Hong, Ha-Cheol;Won, Yong-Jae;Shin, Jin-Chul;Kim, Hyung-Yoon;Seo, Dae-Ha;Hwang, Hung-Goo;Yea, Jong-Doo
    • Korean Journal of Breeding Science
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    • v.42 no.6
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    • pp.632-637
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    • 2010
  • 'Hanseol' is a new very early-maturing, cold tolerant and high quality japonica rice variety developed from a cross of 'Jinbu24' and 'Jinbu25' by the rice breeding team of National Institute of Crop Science (NICS), Rural Development Administration (RDA) in 2009. The heading date of this variety is July 25, which is four days earlier than check variety, 'Jinbubyeo'. 'Hanseol' has 65 cm of culm length, 99 spikelets per panicle, 82.9% of ripened grain rate, and 21.5 g of 1,000 grain-weight of brown rice. This variety shows susceptibility to bacterial leaf blight and virus diseases, and insect pests. It is tolerant to cold stress in terms of less heading delay and high fertility in cold water irrigated cultivation. This variety shows delayed leaf senescence and considerable tolerance to viviparous germination at ripening stage. The milled rice of this variety exhibits translucent, clear non-glutinous endosperm and medium-short grain. 'Hanseol' showed low gelatinization temperature and 6.1% protein content, 19.1% amylose content and good palatability of cooked rice. The milled rice yield of this variety is about 5.43 MT/ha at ordinary culture in local adaptability test for three years. 'Hanseol' would be highly adaptable to mid-north and mid-mountainous areas, and mid-northern alpine area in Korea.

Current status and tasks of the transmission of Gyeonggi Province intangible cultural assets (folk songs) (경기도 향토민요 관련 무형문화재의 전승현황과 과제)

  • Jang, hee-sun
    • (The) Research of the performance art and culture
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    • no.35
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    • pp.405-439
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    • 2017
  • In this article, I suggest issues and tasks in transmission of Gyeonggi Province folk songs after thorough study of designation of Gyeonggi Province folk songs as intangible cultural asset, reproduction and transmission. Intangible cultural assets are classified into seasonal playing and songs. Originally, category or extension of folk songs is above mere songs and it also embraces personal lives as well as village communities. Intangible assets of folk songs are folk art, group events and non-stage events at the same time based on tradition, history, uniqueness, characters of field value. Gyeonggi Province has 9 intangible assets now because of the revocation of several assets (All Gyeonggi Province, Hwasung, Gwacheon) within five years after initial designation of 13 assets in 1998. They are mostly distributed in the north Gyeonggi region where is close to the DMZ and delay in development seems to have enabled the preservation. Most of the intangible cultural assets are farming songs and weeding which show characteristics of Gyeonggi Province. Most of the designees are who performed excavation, recovery, excluding a few cases without designees on designation, and almost all the designee passed away. Number of cases have been revoked because transmission was not completed or some cases were transmitted to groups rather than specific designees. Subscription concert, the biggest and most representative event, is performed once a year with all of the 9 intangible cultural assets in the original complete forms of the designation. Intangible cultural assets are classified into seasonal playing and songs. In general, current performance of the intangible cultural assets and folk songs are same as the originally designated forms and are not in varied forms other than folk songs like songs for rice-planting and weeding. Funeral songs are transmitted in Yangju and Yangpyeong. In terms of the operation, preservation societies having training centers have been performing more constant activities for preservation including lecture, performance and transmission. Members are quite aged and the societies are suffering from lack of support fund for reproduction and transmission. Problems in reproduction and tasks for the transmission I would like to suggest are like followings. First, preservation and value of the cultural assets. Second, new understanding of designation and revocation of the intangible cultural assets. Third, record of performance and sound source. Fourth, liaison with local communities. Fifth, organization of professional resources and establishment of systematic support and management.

Development and Application of Instrument for Level Scale of the Systems Thinking Ability about Carbon Cycle (탄소 순환에 대한 시스템 사고 능력 수준 측정을 위한 검사도구 개발 및 적용)

  • Jeon, Jaedon;Lee, Hyundong;Lee, Hyonyong
    • Journal of The Korean Association For Science Education
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    • v.42 no.4
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    • pp.397-415
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    • 2022
  • As the global warming problem becomes serious, the need for carbon cycle education in school is increasing. Adopting systems thinking ability is needed to understand the carbon cycle systematically. Furthermore, under the rapid change of environment, society, and economy, systems thinking ability is being emphasized as it can strengthen the competencies of students who will be leading the future society. The purposes of this study are as follows: first, is developing the systems thinking instrument for the carbon cycle and the rubric for analysis of systems thinking instrument. The second is analyzing the systems thinking ability of students using the developed instrument and rubric. In order to perform this study, previous studies related to the carbon cycle and systems thinking education were analyzed. Based on the analysis results, the systems thinking instrument for the carbon cycle and rubric were developed. The systems thinking ability was analyzed by implementing the developed instrument and rubric to 172 high school and university students. The results of this study are as follows: first, the systems thinking instrument for the carbon cycle was developed, and a rubric utilization guide was constructed. The instrument and rubric were modified through pilot study for middle school students producing expert opinion in relation to systems thinking and carbon cycle. Second, the systems thinking ability of students was analyzed. Consequently, students had systems thinking ability fully at a low level, such as identifying the variables related to the carbon cycle. However, it was shown that they lacked the systems thinking ability at a high level, such as time delay and feedback processes. The importance of the carbon cycle has been increasing since the global warming is the most pressing issue and significant environmental problem facing us today. Application of the systems thinking ability can contribute to understanding these complex problems and finding fundamental solutions.

Impact and significance of Nongak(農樂) education in Agricultural High School since 1950 on the modern Korean Nongak History (1950년대 중반 이후 농림/농업고등학교에서의 농악(農樂) 교육이 한국농악 현대사에 끼친 영향과 의의)

  • Yang, Ok-Kyung
    • (The) Research of the performance art and culture
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    • no.40
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    • pp.111-136
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    • 2020
  • Agricultural high schools are undergoing a change their name from the mid-1950s to the 2000s. Although it varies slightly depending on the case, it has been changed from 'rural forests' to 'agricultural farms' or 'agricultural industries' and 'life sciences high schools' in turn. In several aricultural high schools had managed Nongak Department(class), it's guarantees the continuity of Korea's traditional folk art. Examples include entertainment and farming in Honam region of Jeonju aricultural high School in North Jeolla Province, Geumsan aricultural high School in South Chungcheong Province, Gimcheon aricultural high School in North Gyeongsang Province. Therefore, the interpretation and significance of studies should follow. This method of Nongak education in modern school institutions is a new phenomenon in the history of Nongak after modern time, the emergence of a whole new pattern of professional entertainment Nongak after paving and Female-Nongak, as well as local traditional folk music. Education here was conducted in such a way that the best performers of the time were invited as guidance teachers among traditional folk artists. Thus, various local and professional music and entertainment were able to be promoted Apart from the social relations of delay, social progress, and economy, the education of farming and music, which consists of teachers and students in public schools, has provided an environment where unlimited freedom is allowed for art forms. In other words, the conditions for a new performance style experiment and creative fusion were met, and the foundation for the development of professional musical performers who had acquired individualized talents from previous generations was laid down in the context of the phenomenon of active stage music and theater performance of outstanding in the culture of Nongak. In other words, the Department of Agriculture and aricultural high school was a very free space compared to other communities' and economic community's agricultural music in social relationships bound by traditional cultural customs. This is why they have created a new style of performance through a new experiment and a different traditional performance repertoire, and their activities have led to a more stylistic expansion from traditional farming. More importantly, the figures who came across Agricultural Nongak department became the main experts of traditional Korean folk music nowdays. Thus, Nongak Department, operated by the Agriculture and Forestry High School, was a space where would give a very important meaning in terms of Nongak history.

Studies on the ecological variations of rice plant under the different seasonal cultures -I. Variations of the various agronomic characteristics of rice plant under the different seasonal cultures- (재배시기 이동에 의한 수도의 생태변이에 관한 연구 -I. 재배시기 이동에 의한 수도의 실용제형질의 변이-)

  • Hyun-Ok Choi
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.3
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    • pp.1-40
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    • 1965
  • To measure variations in some of the important agronomic characteristics of rice varieties under shifting of seedling dates, this study has been carried out at the Paddy Crop Division of Crop Experiment Station(then Agricultural Experiment Station) in Suwon for the period of three years 1958 to 1960. The varieties used in this study were Kwansan, Suwon #82, Mojo, Paltal and Chokwang, which have the different agronomic characteristics such as earliness and plant type. Seeds of each variety were sown at 14 different dates in 10-day interval starting on March 2. The seedlings were grown on seed bed for 30, 40, 50, 60, 70 and 80 days, respectively. The results of this study are as follows: A. Heading dates. 1. As the seeding date was delayed, the heading dates was almost proportionally delayed. The degree of delay was higher in early varieties and lower in late varieties and the longer the seedling stage, the more delayed the heading date. 2. Number of days to heading was proportionally lessened as seeding was delayed in all the varieties but the magnitude varied depending upon variety. In other words, the required period for heading in case of late planting was much shortened in late variety compared with early one. Within a variety, the number of days to heading was less shortened as the seedling stage was prolonged. Early variety reached earlier than late variety to the marginal date for the maximum shortening of days to heading and the longer the seeding stage, the limitted date came earlier. There was a certain limit in seeding date for shortening of days to heading as seeding was delayed, and days to heading were rather prolonged due to cold weather when seeded later than that date. 3. In linear regression equation, Y=a+bx obtained from the seeding dates and the number of days to heading, the coefficient b(shortening rate of days to heading) was closely correlated with the average number of days to heading. That is, the period from seeding to heading was more shortened in late variety than early one as seeding was delayed. 4. To the extent that the seedling stage is not so long and there is a linear relationship between delay of seeding and shortening of days to heading, it might be possible to predict heading date of a rice variety to be sown any date by using the linear regression obtained from variation of heading dates under the various seeding dates of the same variety. 5. It was found out that there was a close correlation between the numbers of days to heading in ordinary culture and the other ones. When a rice variety was planted during the period from the late part of March to the middle of June and the seedling ages were within 30 to 50 days, it could be possible to estimate heading date of the variety under late or early culture with the related data of ordinary culture. B. Maturing date. 6. Within (he marginal date for maturation of rice variety, maturing date was proportionally delayed as heading was delayed. Of course, the degree of delay depended upon varieties and seedling ages. The average air temperature (Y) during the ripening period of rice variety was getting lower as the heading date. (X) was delayed. Though there was a difference among varieties, in general, a linear regression equation(y=25.53-0.182X) could be obtained as far as heading date were within August 1 to September 13. 7. Depending upon earliness of a rice variety, the average air temperature during the ripening period were greatly different. Early variety underwent under 28$^{\circ}C$ in maximum while late variety matured under as low as 22$^{\circ}C$. 8. There was a highly significant correlation between the average air temperature (X) during the ripening period, and number of day (Y) for the maturation. And the relationship could be expressed as y=82.30-1.55X. When the average air temperature during the period was within the range of 18$^{\circ}C$ to 28$^{\circ}C$, the ripening period was shortened by 1.55 days with increase of 1$^{\circ}C$. Considering varieties, Kwansan was the highest in shortening the maturing period by 2.24 days and Suwon #82 was the lowest showing 0.78 days. It is certain that ripening of rice variety is accelerated at Suwon as the average air temperature increases within the range of 18$^{\circ}C$ to 28$^{\circ}C$. 9. Between number of days to heading (X) related to seeding dates and the accumulated average air temperature (Y) during the ripening period, a positive correlation was obtained. However, there was a little difference in the accumulated average air temperature during the ripening period even seeding dates were shifted to a certain extent. C. Culm- and ear-lengths. 10. In general all the varieties didn't show much variation in their culm-lengths in case of relatively early seeding but they trended to decrease the lengths as seeding was delayed. The magnitude of decreasing varied from young seedlings to old ones. Young seedlings which were seeded during May 21 to June 10 didn't decrease their culm-lengths, while seedlings old as 80 days decreased the length though under ordinary culture. 11. Variation in ear-length of rice varieties show the same trend as the culm-length subjected to the different seeding dates. When rice seedlings aged from 30 to 40 days, the ear-length remained constant but rice plants older than 40 days obviously decreased their ear-lengths. D. Number of panicles per hill. 12. The number of panicles per hill decreased up to a certain dates as seeding was delayed and then again increased the panicles due to the development of numerous tillers at the upper internodes. The seeding date to reach to the least number of panicles of rice variety depended upon the seedling ages. Thirty- to 40-day seedlings which were seeded during May 31 to June 10 developed the lowest number of panicles and 70- to 80-day seedlings sown for the period from April 11 to April 21 reached already to the minimum number of panicles. E. Number of rachillae. 13. To a certain seeding date, the number of rachillae didn't show any variation due to delay of seeding but it decreased remarkably when seeded later than the marginal date. 14. Variation in number of rachillae depended upon seedling ages. For example, 30- to 40-day old seedlings which, were originally seeded after May 31 started to decrease the rachillae. On the other hand, 80-day old seedlings which, were seeded on May 1 showed a tendency to decrease rachillae and the rice plant sown on May 31 could develop narrowly 3 or 4 panicles. F. Defective grain and 1.000-grain weights. 15. Under delay of the seeding dates, weight of the defective grains gradually increased till a certain date and then suddenly increased. These relationships could be expressed with two different linear regressions. 16. If it was assumed that the marginal date for ripening was the cross point of these two lines, the date seemed. closely related with seedling ages. The date was June 10- in 30- to 40-day old seedlings but that of 70- to 80-day old seedlings was May 1. Accordingly, the marginal date for ripening was getting earlier as the seedling stage was prolonged. 17. The 1.000-grain weight in ordinary culture was the heaviest and it decreased in both early and late cultures. G. Straw and rough rice weights. 18. Regardless of earliness of variety, rice plants under early culture which were seeded before March 22 or April 1 did not show much variation in straw weight due to seedling ages but in ordinary culture it gradually decreased and the degree was became greater in late culture. 19. Relationship between seeding dates (X) and grain weight related to varieties and seedling ages, could be expressed as a parabola analogous to a line (Y=77.28-7.44X$_1$-1.00lX$_2$). That is, grain yield didn't vary in early culture but it started to decrease when seeded later than a certain date, as seeding was delayed. The variation was much greater in cases of late planting and prolongation of seedling age. 20. Generally speaking, the relationship between grain yield (Y) and number of days to heading (X) was described with linear regression. However, the early varieties were the highest yielders within the range of 60 to 110, days to heading but the late variety greatly decreased its yield since it grows normally only under late culture. The grain yield, on the whole, didn't increase as number of days to heading exceeded more than 140 days.

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Effect of Cooling Timing in the Root Zone on Substrate Temperature and Physiological Response of Sweet Pepper in Summer Cultivation (여름 파프리카 수경재배에서 근권 냉방 시간이 근권 온도와 생리적 반응에 미치는 영향)

  • Choi, Ki Young;Ko, Ji Yeon;Yoo, Hyung Joo;Choi, Eun Young;Rhee, Han Cheol;Lee, Yong-Beom
    • Horticultural Science & Technology
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    • v.32 no.1
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    • pp.53-59
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    • 2014
  • This study aimed to determine an appropriate cooling timing in the root zone for lowering substrate temperature and its effect on physiological response of sweet pepper (Capsicum annum L. 'Orange glory') grown on coir substrate in summer, from the July 16 to October 15, 2012. Daily temperature of substrate, root activity, leaf water potential, first flowering date, and the number of fruits were measured by circulating cool water through a XL pipe in the root zone during either all day (all-day) or only night time (5 p.m. to 3 a.m.; night) from the July 23 to September 23, 2012. For comparison, no cooling (control) was also applied. Between the $23^{rd}$ of July and $31^{st}$ of August (hot temperature period), daily average temperatures in substrates were $25.6^{\circ}C$, $26.1^{\circ}C$, and $29.1^{\circ}C$ for the all-day and night treatment, and control respectively. About 1.8 to $5^{\circ}C$ lower substrate temperature was observed in both treatments compared to that of control. In sunny day ($600-700 W{\cdot}m^{-2}{\cdot}s^{-1}$), the highest temperature of substrate was measured between 4 p.m. and 5 p.m. under both the all-day and night treatments, whereas it was measured between 7 p.m. and 8 p.m. under the control. Substrate temperatures during the day (6 a.m. to 8 p.m.) and night (8 p.m. to 6 a.m.) differed depending on the treatments. During the day and night, averaged substrate temperature was lower about $3.3^{\circ}C$ and $4.0^{\circ}C$ for the all-day, and $2.1^{\circ}C$ and $3.4^{\circ}C$ for the night treatment, compared to that of control. In the all-day and night treatment, the TD [TD = temperature of (control)] was greater in bottom than that of other regions of the substrate. Between the day and night, no different TD values were observed under the all-day treatment, whereas under the night treatment there was difference with the greatest degree in the bottom of the substrate. During the hot temperature period, total numbers of days when substrate temperature was over $25^{\circ}C$ were 40, 23 and 27 days for the control, all-day, and night treatment, respectively, and the effect of lowering substrate temperature was therefore 42.5% and 32.5% for the all-day and night treatment, respectively, compared to that for the control. Root activity and leaf water potential of plants grown under the all-day treatment were significantly higher than those under the night treatment. The first flowering date in the all-day treatment was similar to that in the night treatment, but 4-5 day faster than in the control. Also, the number of fruits in both treatments was significantly higher than that in the control. However, there was no effect of root zone cooling on eliminating delay in fruiting caused by excessively higher air temperature (> $30^{\circ}C$), although the substrate temperature was reduced $18^{\circ}C$ to $5^{\circ}C$. These results suggest that the method of cooling root zone temperature need to be incorporated into the lowering growing temperature for growth and fruit set of health paprika.

Epidemiology and Control of Rice Blast in Korea (한국(韓國)에서의 도열병(病) 발생(發生), 만연(蔓延)과 그 방제(防除))

  • Park, Jong Seong
    • Korean Journal of Agricultural Science
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    • v.12 no.2
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    • pp.356-369
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    • 1985
  • In Korea, inevitable researches for the blast control exactly started from 1927 by the organization of Office of Rural Development with the local extensive outbreak of panicle blast at Jeonlla Buk-Do Province in 1926. At present, the rice blast is still one of the most destructive and widespread diseases in spite of considerable contributions by rice scientists, particularly plant pathologists during last 55 years in Korea. Rice blast control and management are very difficult because of the marked variability in pathogenicity of the blast fungus. From the results obtained through the disease surveys during last 70 years, different 3 prevalence type of blast such as bimodal leaf-blast type, bimodal panicle-blast type and bimodal continual blast type were recognized. In generally speaking, pattern of blast outbreak is said to be characterized by severe outbreak of panicle blast after slight outbreak of leaf blast with discontinuity between leaf and panicle blast. So we have to pay much attention for successful management of panicle blast giving direct influence to rice yield. Main factors induce blast epidemic were pointed out to be breakdown of the disease resistance, nutritional unbalance such as excess application of nitrogen, delay of transplantation and longspell of rain fall by extensive surveys and researches on blast during last 70 years in Korea. The fact some of Japonica varieties such as Kokuryomiyako, Tamanishiki, Ginbozu and Pungok belong to varietal group A had been cultivated with extensive acrage over 30 years in this country should be mentioned by Korean rice scientists. Differences in field resistance between varieties in the same group are detectable and apparently small but sometimes epidemiologically significant differential effects may be found out in case of blast. Much more attention should be payed to accumulate the knowledges on field resistance for successful management of blast. Excess application of nitrogen is more effective to outbreak of panicle blast than that of leaf blast of IR varieties. In comparatively low level application of nitrogen infection rate of panicle blast of IR varieties is considerably high. Low temperature effects on outbreak of blast is very great. It results in remarkable increase of the inoculum potential on the leaf lesions and infection of panicle blast in leaf sheathes of IR varieties during the booting stage. In economic point of view, it is concluded that 5 times sprays of effective fungicides including 3 times before and 2 times after heading is good enough to control blast. We have experienced no one of control measures for blast is superior to all others. The integrated control measures was established as guideline of blast control around 1950 in Korea. This guideline must be helpful for rice growers as long as rice growing continue.

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