Chemical and Physical Characteristics of Expanded Rice Husk Medium on Growth of Rice Seedling

Ko Jonghan,Ham Jin Kwan,Kim Yong Bok,Kim Kyung Hee,Lee Byun Woo,Lee Youn Su The Korean Society of Crop Science 2005 Korean journal of crop science Vol.50 No.2

Expanded rice husk (ERR) is different from commercial rice seedling media in chemical and physical properties such as pH, permeability, and water content. This study was conducted to test a possibility of improving rice seedling growth by improving the texture of ERR as a rice seedling medium. The seedling media used were a commercial seedling medium (CSM), rice husk, and ERR 1, 2, 3, and 4 with different expansion degrees. The pH of the ERHs ranged from 6.3 to 6.8. As the expansion rate increased, ERR particle sizes decreased, and water permeability and absorption rates improved. No significant differences in shoot dry weight and rate of maturity were found among the seedlings cultivated in the different ERH media. However, the mat formation of seedling roots became loose as the expansion rates were decreased. Further studies are necessary to determine the cause of poor root growth in ERH media.

Effect of Expanded Rice Husk Medium on Rice Seedling for Machine Transplanting

Jonghan Ko,Doo Yeol Kim,Jong Gu Sa,Byun Woo Lee,Youn Su Lee 韓國作物學會 2005 Korean journal of crop science Vol.50 No.1

Rice farmers can save labor and expenses by using expanded rice husk (ERH) as a seedling medium since ERH is lighter and cheaper than other commercial seedling media (CSM). This study was carried out to develop a method for rice seedling cultivation using ERH as a seedling medium. It is suggested that a mixture of 60~% of ERH and 40~% of a CSM could be used as a seedling medium; the planting densities would be 240g per tray for infant seedlings and 200 g for young seedlings; and nitrogen (N) would be applied at a rate of 1g per tray for infant seedlings prior to planting and 2g per tray for young seedlings with division. Great care should be taken to use CO(NH2)2 as an N-source fertilizer. These results would lay a foundation for the rice seedling cultivation with ERH as a medium.

Chemical and Physical Characteristics of Expanded Rice Husk Medium on Growth of Rice Seedling

Jonghan Ko,Jin Kwan Ham,Yong Bok Kim,Kyung Hee Kim,Byun Woo Lee,Youn Su Lee 韓國作物學會 2005 Korean journal of crop science Vol.50 No.2

Expanded rice husk (ERR) is different from commercial rice seedling media in chemical and physical properties such as pH, permeability, and water content. This study was conducted to test a possibility of improving rice seedling growth by improving the texture of ERR as a rice seedling medium. The seedling media used were a commercial seedling medium (CSM), rice husk, and ERR 1, 2, 3, and 4 with different expansion degrees. The pH of the ERHs ranged from 6.3 to 6.8. As the expansion rate increased, ERR particle sizes decreased, and water permeability and absorption rates improved. No significant differences in shoot dry weight and rate of maturity were found among the seedlings cultivated in the different ERH media. However, the mat formation of seedling roots became loose as the expansion rates were decreased. Further studies are necessary to determine the cause of poor root growth in ERH media.

Simulation for Irrigation Management of Corn in South Texas

Jonghan Ko,Giovanni Piccinni 韓國作物學會 2008 Korean journal of crop science Vol.53 No.2

Interest is growing in applying simulation models for the South Texas conditions, to better assess crop water use and production with different crop management practices. The Environmental Policy Integrated Climate (EPIC) model was used to evaluate its application as a decision support tool for irrigation management of com (Zea mays L.) in South Texas of the U.S. We measured actual crop evapotranspiration (ETc) using a weighing lysimeter, soil moisture using a neutron probe, and grain yield by field sampling. The model was then validated using the measured data. Simulated ETc using the Hargreaves-Samani equation was in agreement with the lysimeter measured ETc. Simulated soil moisture generally matched with the measured soil moisture. The EPIC model simulated the variability in grain yield with different irrigation regimes with r2 value of 0.69 and root mean square error of 0.5~;ton~;ha-1 . Simulation results with farm data demonstrate that EPIC can be used as a decision support tool for com under irrigated conditions in South Texas. EPIC appears to be effective in making long term and pre-season decisions for irrigation management of crops, while reference ET and phenologically based crop coefficients can be used for inseason irrigation management.

Global Warming Likely Reduces Crop Yield and Water Availability of the Dryland Cropping Systems in the U.S. Central Great Plains

Ko, Jonghan,Ahuja, Lajpat R. 한국작물학회 2013 Journal of crop science and biotechnology Vol.16 No.4

We investigated the impact of GCM-projected climate change on dryland crop rotations of wheat-fallow and wheat-corn-fallow in the Central Great Plains (Akron in Colorado, USA) using the CERES 4.0 crop modules in RZWQM2. The climate change scenarios for $CO_2$, temperature, and precipitation were produced by 22 GCM projections for Colorado based on the A1B scenario. The climate change for years 2050 and 2075 was super-imposed on measured 30-year-baseline climate data (1989-2008). For all the cropping rotations and projection years, simulated yields of wheat and corn decreased significantly (P < 0.05) with increasing temperatures. The yield declines due to the elevated temperatures should be attributable to the shortening of crop maturity duration and concurrent decreases in soil water and evapotranspiration. The model was also projected to decrease crop yields for the combined climate change scenarios of $CO_2$, temperature, and precipitation in the dryland cropping rotations.

Effect of Expanded Rice Husk Medium on Rice Seedling for Machine Transplanting

Ko Jonghan,Kim Doo Yeol,Sa Jong Gu,Lee Byun Woo,Lee Youn Su The Korean Society of Crop Science 2005 Korean journal of crop science Vol.50 No.1

Rice farmers can save labor and expenses by using expanded rice husk (ERH) as a seedling medium since ERH is lighter and cheaper than other commercial seedling media (CSM). This study was carried out to develop a method for rice seedling cultivation using ERH as a seedling medium. It is suggested that a mixture of $60\%$ of ERH and $40\%$ of a CSM could be used as a seedling medium; the planting densities would be 240g per tray for infant seedlings and 200 g for young seedlings; and nitrogen (N) would be applied at a rate of 1g per tray for infant seedlings prior to planting and 2g per tray for young seedlings with division. Great care should be taken to use $CO(NH_2)_2$ as an N-source fertilizer. These results would lay a foundation for the rice seedling cultivation with ERH as a medium.

Use of Remotely-Sensed Data in Cotton Growth Model

Jonghan Ko,Stephan J. Maas 韓國作物學會 2007 한국작물학회지 Vol.52 No.4

Remote sensing data can be integrated into crop models, making simulation improved. A crop model that uses remote sensing data was evaluated for its capability, which was performed through comparing three different methods of canopy measurement for cotton(Gossypium hirsutum L.). The measurement methods used were leaf area index(LAI), hand-held remotely sensed perpendicular vegetation index(PVI), and satellite remotely sensed PVI. Simulated values of cotton growth and lint yield showed reasonable agreement with the corresponding measurements when canopy measurements of LAI and hand-held remotely sensed PVI were used for model calibration. Meanwhile, simulated lint yields involving the satellite remotely sensed PVI were in rough agreement with the measured lint yields. We believe this matter could be improved by using remote sensing data obtained from finer resolution sensors. The model not only has simple input requirements but also is easy to use. It promises to expand its applicability to other regions for crop production, and to be applicable to regional crop growth monitoring and yield mapping projects.

치매 의심과 비치매간의 인지기능 비교

고효진,박종한 大韓神經精神醫學會 1992 신경정신의학 Vol.31 No.6

Cognitive functions, including memory, were compared between the elderly with non-dementia and the elderly with questionable dementia in a rural community. They were all 65 years old or more. Short-term and long-term memories were significantly poorer in people with questionable dementia. The differences were not due to age. However, all cognitive functions except for short-term and long-term memories were similar between the two groups. These findings suggest that questionable dementia may be qualitatively different from non-dementia and may he classified as early or very mild dementia.

경북 영일군 어느 면지역 노인들에서 치매의 원인적 분류 및 주요 치매의 상대적 유병율

고효진,박종한 大韓神經精神醫學會 1991 신경정신의학 Vol.30 No.5

Dementia was etiologically classified in the elderly of a Myun area of Yungil county, Kyungpook province. Diagnosis of dementia was according to the DSM-Ⅲ-R. Important findings were summarized as follows: 1) Frequent causes of dementia were Alzheimer type(61.5%), multi-infarct(12.8%), mixed dementia of Alzheimer type and multi-infarct(9.0%), and alcoholic(7.7%). 2) Prevalence of the Alzheimer type was significantly higher in females, while alcoholic dementia was limited to male sex. Prevalence of multi-infarct dementia was similar in two sexes. 3) Dementia of the Alzheimer type was the main factor in explaining both higher prevalence of dementia in females and its increasing trend with age. 4) It seems that there is a critical age for the development of dementia of Alzheimer type and that the age is younger in females than in males.

치매에 대한 어느 역학적 연구에서 진단의 일치도

고효진,박종한 大韓神經精神醫學會 1993 신경정신의학 Vol.32 No.5

Diagnostic agreement of dementia between two diagnosticians was studied. In Study 1(n=94), the subjects were conjointly assessed by two psychiatrists regarding cognitive status, neurological and physical status and medical conditions. Interviews with the next of kin were conducted to obtain informations about cognitive decline, past medical and psychiatric histories, and alcohol and drug use problems. In Study 2(n=83), one psychiatrist collected all the data about the subjects, and another psychiatrist was allowed to use only the data of cognitive status in diagnosing them. DSM-Ⅲ-R was employed as the criteria for dementia. Questionable dementia was introduced to diagnose subjects whose cognitive impairment was insufficient to diagnose dementia. Diagnostic categories were either dementia, questionable dementia or nondementia. In the estimation of diagnostic agreement, questionable dementia was considered as nondementia at one time and as dementia at another time.. κ values were 0.845 to 0.915 in Study 1, and 0.618 to 0.766 in Study 2. κ increased when questionable dementia was considered as dementia. Findings of the present study may suggest that diagnostic accuracy was high in the previous epidemiological studies of authors.