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Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

Degradation of Nucleotides and Their Related Compounds in Sea Foods during Processing and Storage VI. Degradation of Nucleotides and Their Related Compounds in File Fish Navodon modestus and Yellowfin Puffer Fugu xanthopterum Muscle during Drying (수산식품(水産食品)의 가공(加工) 및 보장중(保藏中)의 핵산관련물질(核酸關聯物質)의 변화(變化)에 관한 연구(硏究) 제6보 말쥐치 및 까치복 건조중(乾燥中)의 핵산관련물질(核酸關聯物質)의 변화(變化))

  • Lee, Eung-Ho;Chung, Seung-Yong;Kim, Yong-Gun;Yang, Sung-Tack;Kim, Soo-Hyun
    • Korean Journal of Food Science and Technology
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    • v.6 no.3
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    • pp.177-184
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    • 1974
  • File fish Navodon modestus was dehydrated in cabinet type hot-sir drier at $48-50^{\circ}C$ for 11 hours and also yellowfin puffer Fugu xanthopterum was dried in open air at $26-28^{\circ}C$ for 30 hours. Nucleotides and their related compounds were collected by extraction with cold perchloric acid and their amounts were determined by anion exchange column chromatography. The contents of ADP, IMP, ATP and hypoxanthine in fresh file fish muscle were 22.9, 12.1, 4.9, and 3.2 ${\mu}mole/g,$ dry wt. respectively. AMP and inosine were 0.9 ${\mu}mole/g,$ dry wt. equally. In fresh yellowfin puffer muscle, the contents of ADP, ATP, AMP, inosine and hypoxanthine were 25.6, 2.4, 1.6, 0.3, 0.6, and 0.4 ${\mu}mole/g,$ dry wt. respectively. In the case of file fish, ADP and ATP tended to degrade rapidly during hot-air dehydration. The contents of IMP were decreased slightly while AMP and inosine were increased. And another case of yellowfin puffer, ADP also tended to degrade rapidly during sun drying while AMP, IMP, inosine and hypoxanthine were increased. Especially, in both case of file fish and yellowfin puffer, inosine was increased twenty five and thirty five times during drying respectively.

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A Study on the Characteristics of Descriptions of the Perspiration in "Hwangjenaegyeong(黃帝內經)" (황제내경(黃帝內經)에 보이는 한(汗)관련 서술(敍述)의 특징(特徵)에 대한 고찰(考察))

  • Lyu, Jeong-Ah;Jang, Woo-Chang;Baik, You-Sang;Jeong, Chang-Hyun
    • Journal of Korean Medical classics
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    • v.23 no.2
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    • pp.205-223
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    • 2010
  • In Korean Traditional Medicine(abbreviated to K.T.M.), hyperhidrosis and anhidrosis are the targets of the medical treatment. Furthermore sweating appearance is also one of the important symptoms which explain a particular situation of the patient in K.T.M. And at "Sanghanron(傷寒論)" which is a traditional chief clinical bible written by Jang Gi(張機) later Han dynasty(漢代) in China made full use of the various kinds of diaphoresis[汗法] as a main medical treatment with purgation therapy[下法] and emetic therapy[吐法]. So the sweat in itself not only is the disease, but also is one of the symptoms explain a disease pattern. This thesis inquires into "Hwangjenaegyeong(黃帝內經)" referring to sweat which is the origin of recognition to the sweat in K.T.M. Some theses similar to this research had been made progresses and already reported, but most of them have classified the contents into biology, pathology, diagnosis, treatment after the model of western medical theory. In the aspect of comparative studying with other literature and clinic practical using, we found characteristics of referring to sweat in "Hwangjenaegyeong(黃帝內經)". And we classify the characteristics into some categories as follows. 1. There are some terms which make a title including sweat and symbolize the characteristics, for example sweat of soul[魄汗], sweat of death[絶汗], sweat of streaming[灌汗], sweat of weakness[白汗], sweat of sleep[寢汗], sweat of bright and heat[炅汗], sweat of kidney[腎汗], sweat of escaping[漉汗], cold sweat[寒汗], sweat on the head[頭汗], hyperhidrosis[多汗], heavy sweat[大汗]. But there aren't spontaneous sweat[自汗] or sweat like a thief[盜汗] which are the normal terms referring to sweat in history of K.T.M. And there are several descriptions about sweat appearance such as sweating in half of body[汗出偏沮], sweating in the rear end and thigh and knee[汗出尻陰股膝], hyperhidrosis in the neck and aversion to wind[頸多汗惡風], hyperhidrosis in the head and face and aversion to wind[頭面多汗惡風], cannot stopping the sweating under head[頭以下汗出不可止], make a person sweat to one's feet[令汗出至足], sweating like escaping[漯漯然汗出], sweating like soaking[汗出如浴], sweating become moist[汗出溱溱], hardly escaping sweat[汗大泄], escaping sweating[漉漉之汗], sweat moisten the pores [汗濡玄府], ceaseless sweating like pouring[汗注不休] sweating like pouring and vexation[汗注煩心], damp with sweat[汗汗然], sweating spontaneously[汗且自出], removal of fever with sweat drying[熱去汗稀]. That can be divided into sweat region and sweat form. 2. There are detailed explanations of the principle of perspirations caused by hot weather, hot food, hard working and meeting damp pathogen. 3. There are some explanations of the principle of removing fever due to the excessive heat from internal and external body through sweating by replenishing the body fluid. And many descriptions about overcoming the febrile disease by dropping temperature through sweating and many diaphoresis for curing. 4. There are some descriptions about five Jang organs perspirations and attachment of five mucous body fluid to five Jang organs. 5. There are pathogenic progresses after sweating affected by the Six Atmospheric Influences and water. And detailed explanations of disease mechanism a sweat leading to another disease. 6. There are descriptions about various sweat absent situations.

Variations of Temperature, Chemical Component and Helium Gas of Geothermal Water by Earthquake Events in Pohang Area (포항 지열수의 지진에 의한 수온, 화학성분 및 헬륨가스의 변화)

  • Lee, Yong Cheon;Jeong, Chan Ho;Lee, Yu Jin;Kim, Young-Seog;Kang, Tae-Seob
    • The Journal of Engineering Geology
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    • v.31 no.4
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    • pp.647-658
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    • 2021
  • In this study, the change of temperature, chemical composition, and helium gas of thermal water in Pohang area was observed from January 2018 to June 2019 in order to interpret the relationship with earthquake events. During observation period earthquakes above M 2.0 within 100 km in a radius from a geothermal well occurred 58 including two earthquake events with a magnitude of 3.0~3.9 and two earthquake events with a magnitude of 4.0~4.9. We introduce a q-factor and earthquake effectiveness (ε) to express the influence of each earthquake as magnitude and distance factors. The geothermal well of 715 m deep was developed in the Bulguksa biotite granite, and the water temperature was observed in the variation from 51.8 to 56.3℃ during monitoring period. At M 4.1 and M 4.6 earthquake events, the increase of geothermal water temperature (𝜟T 2.6~4.5℃) was recorded, and slight change in specific ionic components such as SO4 and Cl, and of chemical types on the Piper diagram were observed. In the 3He/4He vs 4He/20Ne diagram, the original mixing ratio of helium isotope before and after the magnitude 4.1 earthquake was slightly changed from 83.0% to 83.2% of crust-origin 4He, and the from 16.3% to 16.7% of mantle-origin 3He. Hot-cold water mixing ratio before and after earthquakes by using the quartz and chalcedony solubility curves of the silica-enthalpy mixing model was calculated to interpret the temperature change of geothermal water. The model calculation shows the increase of 6.93~7.72% and 1.65~4.94% of hot water ratio at E1 and E2 earthquakes, respectively. Conclusively, the magnitude of earthquake for observable change in the temperature and helium isotope of thermal water is of 4.1 or higher and q-factor value of 30.0 or higher in the study site.

A Study of Students' Knowledge Level of Dental Health Care (초중등학생의 구강보건관리에 대한 인식도 조사)

  • Kim, Kyo-Woong;Nam, Chul-Hyun
    • Journal of the Korean Society of School Health
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    • v.13 no.2
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    • pp.295-317
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    • 2000
  • This study was conducted to prevent oral disease of primary school, middle school, and high school students, providing basic data for the development of oral health education programs. Data were collected from 898 primary school, middle school, and high school students from March 2, 1999 to May 31, 1999. The results of this study are summarized as follows; 1) The subjects of this study were primary school students(32.6%), middle school students(33.0%), and high school students(34.4%). Boy students were slightly more prevalent than girl students. That is, primary school boys were 56.3%, middle school boys were 53.2%, and high school boys were 52.6%. 2) According to the self-judgement of oral health, primary school students were better than middle/high school students and boy students were better than girl students, 63.5% of primary school students and 57.8% of middle/high school students brushed their teeth once or twice a day. 3) 76.3% of middle/high school students and 63.5% of primary school students experienced dental caries. Girl students were higher than boy students in experiencing dental caries, 35.9% of primary school students and 27.6% of middle/high school students experienced periodontal disease. 4) 22.9% of primary school students and 7.9% of middle/high school students received oral examinations periodically. Girl students showed a higher rate than boy students in primary school, while boy students showed a higher rate than girl students in middle/high school. 5) Explaining to the reasons for reluctant visits to dental hospitals and clinics, 'no time to go' was highest(22.9% of primary school students; 27.4% of middle/high school students) and the rate of 'feeling scared' was second highest. Middle/high school students were more reluctant to visit dental hospitals and clinics than primary school students. In case of problematic symptoms in the mouth, the rate of 'feeling painful or cold in teeth when eating cold or hot foods' was highest, 71.3% of primary school students was concerned about oral health, while 68.6% of middle/high school students was concerned about it. 6) In gathering to the sources of information on oral health, the rate of medical institutions was highest(30.0%) in primary school students, while the rate of family members or persons around them was highest in middle/high school students. 7) 54.9% of primary school students received oral health education, while 13.1% of middle/high school students received it. Only 4.7% of middle school and high school girls received it. In relation to dental health education, the rate of 'possibility of prevention of oral caries or disease of the gum' was highest. 79.5% of primary school students and 80.3% of middle school students answered that they would attend oral health education. 8) 60.4% of primary school students and 60.2% of middle/high school students think the purpose of oral health is to prevent dental caries and disease of the gums. In preventing dental caries, 78.8% of primary school students and 71.8% of middle school students thought that periodical oral examination was effective, 88.4% of primary school students and 88.8% of middle/high school thought that brushing one's teeth was effective and 64.1% of primary school students and 50.7% of middle school students thought that the use of toothpaste containing fluoride was effective. In preventing periodontal disease, 91.1% of primary school students and 90.2% of middle/high school students thought that brushing one's teeth was effective, while 72.4% of primary school students and 70.3% of middle/high school students thought that teeth cleaning was effective. 9) 16.0% of middle school students and 12.7% of high school students thought that their oral health condition was healthy. According to individual experiences in dental treatment, the rate of experience of middle school students was higher than that of high school students, 12.7% of middle school students received oral examinations periodically, while only 3.3% of high school students did so. 10) In cases of 'having no problematic symptoms in the mouth' and 'concerns about oral health', the rate of middle school students was higher than that of high school students. In gathering obtaining information on oral health, the rate of obtaining it through broadcast media including TV, Radio, etc. was highest in middle school students, while the rate of obtaining it through family members or persons around them was highest in high school students. 11) 81.7% of middle school students have not received oral health education. In case of girl students, 97.3% have not received it in high school students. 85.6% of middle school students and 151.2% of high school students think that oral health education is necessary. 12) According to the knowledge level of oral health, the point of high school students($26.33{\pm}2.33$) was similar to the point of high school students($26.23{\pm}2.30$). It appeared that the point of primary school students was highest($26.35{\pm}2.50$) The more concerned about oral health the students were the higher the knowledge level of oral health was. In conclusion, the middle/high school students' knowledge level of oral health was lower than primary school students. The rate of middle/high School students' experience in oral health education was too low. Therefore, it is necessary to intensify oral health education for middle/high school students. Especially, the necessity of oral health education to girl students is strongly recommended. Developing an oral health education program for primary school, middle school, and high school students, related public authority and organizations, teachers; and dentists must actively make efforts together in order to maintain healthy teeth through having students prevent dental caries and periodontal disease.

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The Actual Management State of Trial Contact Lenses and Lens Care Products in Local Optical Shops (안경원의 시험착용 콘택트렌즈 및 관리용품 관리 실태)

  • Park, Mijung;Lee, Unjung;Kim, So Ra
    • Journal of Korean Ophthalmic Optics Society
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    • v.16 no.4
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    • pp.391-401
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    • 2011
  • Purpose: In the present study, the actual management state of trial contact lenses and lens care products in local optical shops was surveyed and analyzed to reduce the risk of lens complication possibly induced by neglecting lens care. Methods: The feeling of contact lens wearers during the wear of trial contact lenses was surveyed. Futhermore, the actual management state of trial contact lenses such as cosmetic lens and RGP lens and lens care products was also investigated by surveying opticians who trade contact lenses in local optical shops. Results: It was found that consumers trusted the sanitary conditions of the lens since trial cosmetic contact lens and RGP lens were cleaned before and after trails by over 98% of opticians in local optical shops. For trial cosmetic lens, cleaning with normal saline, multipurpose solution for soft lens and combination of saline and multipurpose solution were 38.5%, 40.5% and 21%, respectively, before trials. After trials, cosmetic lenses were cleaned with normal saline, multipurpose solution for soft lens and a combination of saline and multipurpose solution were 13%, 75%, and 12%, respectively. On the other hand, cleaning with normal saline, multipurpose solution for RGP lens and combination of saline and multipurpose solution were 28.5%, 38.5% and 33%, respectively, before trying trial RGP lens. After trials, RGP lenses were cleaned with normal saline, multipurpose solution for RGP lens and a combination of saline and multipurpose solution were 2.5%, 70%, and 27.5%, respectively, indicating that relatively many opticians followed the lens cleaning regimen. In local optical shops, the cleaning trial cosmetic lens was mainly conducted at every 10 days or a month and the washing cycle of cosmetic lens case was in a month or 2~3 months. The cleaning interval of trial RGP lens was primarily in a month or 2~3 months. For those lens cases, more than 75% of opticians washed them with a surfactant and then rinsed with cold water. The storing periods of lens care products were primarily in a week for saline and in a month and 2~3 months indicating that storing period of lens care products was relatively well-kept in local optical shops. Conclusions: It is thought that the concern about any microbial infection is not that high since trial contact lenses and lens care products were generally well-managed by opticians in local optical shops from the results above. However, better public eye health and better public confidence in opticians may be possible if further strengthen in avoidance of lens cleaning with saline, keep of cleaning cycles within 2 weeks and rinsing of lens cases with hot water happens.

The Chemical Composition of Abies koreana Wilson Wood (구상나무(Abies koreana Wilson)재(材)의 화학적(化学的) 조성(組成))

  • Moon, Chang Kuck;Pack, Chong Yawl;Kang, Wee Pyung
    • Journal of Korean Society of Forest Science
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    • v.50 no.1
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    • pp.1-4
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    • 1980
  • The Chemical components of Abies koreana Wilson grown in Korea were analized. The results obtained were summarized as follows. 1. The ash content is ca 0.56% on the average, and of the range is 0.33 to 0.76%. 2. The cold water extractive content is ca 8.76% on the average and of the range is 5.55 to 12.5%. 3. The hot water extractive content is ca 10.16% on the average and of the range is 4.80 to 13.65%. 4. Basic extractive content is ca 14.60% on the average and of the range is 5.51 to 25.44%. 5. The alcohol benzol soluble fraction is ca 4. 23% and of the range is 2.94 to 5.44%. 6. The holocellulose content is ca 76.49% on the average and of the range is 73.68% to 79.10%. 7. The cellulose content is ca 56.30% on the average and of the range is 46.02% to 61. 33%. The cellulose contains 78.54% ${\alpha}$-cellulose, 7.66% ${\beta}$-cellulose and 14.04% ${\gamma}$-cellulose respectively. 8. The Klason lignin content is ca 25.03% on the average and of the range is 22.5 to 27.0%. In conclusion, ash content is comparable to the other needle leaf trees. It has 76.49% in holocellulose content which is comparable value to the Pinus densiflora's. It has lower value than the Pinus densiffora in pentosan and lignin content. Having not resin cannal in xylem and long tracheid, this wood could be usable industrial material.

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Development and Performance Evaluation of an Animal SPECT System Using Philips ARGUS Gamma Camera and Pinhole Collimator (Philips ARGUS 감마카메라와 바늘구멍조준기를 이용한 소동물 SPECT 시스템의 개발 및 성능 평가)

  • Kim, Joong-Hyun;Lee, Jae-Sung;Kim, Jin-Su;Lee, Byeong-Il;Kim, Soo-Mee;Choung, In-Soon;Kim, Yu-Kyeong;Lee, Won-Woo;Kim, Sang-Eun;Chung, June-Key;Lee, Myung-Chul;Lee, Dong-Soo
    • The Korean Journal of Nuclear Medicine
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    • v.39 no.6
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    • pp.445-455
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    • 2005
  • Purpose: We developed an animal SPECT system using clinical Philips ARGUS scintillation camera and pinhole collimator with specially manufactured small apertures. In this study, we evaluated the physical characteristics of this system and biological feasibility for animal experiments. Materials and Methods: Rotating station for small animals using a step motor and operating software were developed. Pinhole inserts with small apertures (diameter of 0.5, 1.0, and 2.0 mm) were manufactured and physical parameters including planar spatial resolution and sensitivity and reconstructed resolution were measured for some apertures. In order to measure the size of the usable field of view according to the distance from the focal point, manufactured multiple line sources separated with the same distance were scanned and numbers of lines within the field of view were counted. Using a Tc-99m line source with 0.5 mm diameter and 12 mm length placed in the exact center of field of view, planar spatial resolution according to the distance was measured. Calibration factor to obtain FWHM values in 'mm' unit was calculated from the planar image of two separated line sources. Te-99m point source with i mm diameter was used for the measurement of system sensitivity. In addition, SPECT data of micro phantom with cold and hot line inserts and rat brain after intravenous injection of [I-123]FP-CIT were acquired and reconstructed using filtered back protection reconstruction algorithm for pinhole collimator. Results: Size of usable field of view was proportional to the distance from the focal point and their relationship could be fitted into a linear equation (y=1.4x+0.5, x: distance). System sensitivity and planar spatial resolution at 3 cm measured using 1.0 mm aperture was 71 cps/MBq and 1.24 mm, respectively. In the SPECT image of rat brain with [I-123]FP-CIT acquired using 1.0 mm aperture, the distribution of dopamine transporter in the striatum was well identified in each hemisphere. Conclusion: We verified that this new animal SPECT system with the Phlilps ARGUS scanner and small apertures had sufficient performance for small animal imaging.

Meteorological Constraints and Countermeasures in Major Summer Crop Production (하작물의 기상재해와 그 대책)

  • Shin-Han Kwon;Hong-Suk Lee;Eun-Hui Hong
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.27 no.4
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    • pp.398-410
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    • 1982
  • Summer crops grown in uplands are greatly diversified and show a large variation in difference with year and location in Korea. The principal factor for the variation is weather, in which precipitation and temperature play a leading role and such a weather factors as wind, sun lights also influence production of the summer crops. Since artificial control of weather conditions as a main stress factor for crop production is almost impossible, it must be minimized only by an improvement of cultivation techniques and crop improvement. Precipitation plays a role as one of the most important factor for production of the summer crops and it is considered in two aspects, drought and excess moisture. This country, which belongs to monsoon territory, necessarily encounter one of this stress almost every year, even though the level is different. Therefore, the facilities for both drought and excess moisture are required, but actually it is not easy to complete for them. On this account, crops tolerant to drought, excess moisture and pests should be considered for establishing summer crops. For the districts damaged habitually every season, adequate crops should be cultured and appropriate method of planting, drainage and weed control should be applied diversely. Injuries by temperature is mainly attributed to lower temperature particularly in late fall and early spring, although higher temperature often causes some damages depending upon the kind of crops. Sometimes, lower temperature in summer season playa critical role for yield reduction in the summer crops. However, certain crops are prevented to some extent from this kind of stress by improving varieties tolerant to cold, hot weather or early maturing varieties. As is often the case, control of planting time or harvesting is able to be a good management for escaping the stress. Lodging, plant diseases and pests are considered as a direct or indirect damage due to weather stress, but these are characters able to be overcome by means of crop improvement and also controlled by other suitable methods. In addition, polytical supports capable of improving constitution of agriculture into modern industry is urgently required by programming of data for the damages, establishment of damage forecasting and compensation system.

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Study for Automatic Exposure Control Technique (AEC) in SPECT/CT for Reducing Exposure Dose and Influencing Image Quality (SPECT/CT에서 자동노출제어(AEC)를 이용함으로써 얻어지는 영상의 질 평가와 피폭선량 감소에 관한 고찰)

  • Yoon, Seok-Hwan;Lee, Sung-Hwan;Cho, Seong-Wook;Kim, Jin-Eui
    • The Korean Journal of Nuclear Medicine Technology
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    • v.18 no.2
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    • pp.33-38
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    • 2014
  • Purpose Auto exposure control (AEC) in SPECT/CT automatically controls the exposure dose (mA) according to patient's shape and size. The aim of this study was to evaluate the effect of AEC in SPECT/CT on exposure dose reduction and image quality. Materials and Methods The model of SPECT/CT used in this study was Discovery 670 (GE, USA), Smart mA for AEC; and $^{99m}Tc$ as a radioisotope. To compare SPECT and CT images by CT exposure dose variation, we used a standard technique set at 80, 100, 120, 140 kVp, 10, 30, 50, 100, 150, 200, 250 mA, and AEC at 80, 100, 120, 140 kVp, 10-250 mA. To evaluate resolution and contrast of SPECT images, triple line phantom and flangeless Esser PET phantom were used. For CT images, noise and uniformity were checked by anthropomrphic chest phantom. For dose evaluation to find DLP value, anthropomorphic chest phantom was used and the CT protocol of torso was applied by standard technique (120 kVp, 100 mA) and AEC (120 kVp, 10-250 mA). Results When standard and AEC were applied, the resolutions at SPECT images with attenuation correction (AC) were the same as FWHM by center 3.65 mm, left 3.48 mm, right 3.61 mm. Contrasts of standard and AEC showed no significant difference: standard 53.5, 29.8, 22.5, 15.8, 6.0, AEC 53.5, 29.6, 22.4, 15.7, 6.1 In CT images, noise values at standard and AEC were 15.4 and 18.5 respectively. The application of AEC increases noise but the value of coefficient variation were 33.8, 24.9 respectively, obtaining uniform noise image. The values of DLP at standard and AEC were 426.78 and 352.09 each, which shows that the application of AEC decreases exposure dose more than standard by approximately 18%. Conclusion The results of our study show that there was no difference of AC in SPECT images based on the CT exposure dose variation at SPECT/CT images. It was found that the increased CT exposure dose leads to the improvement of CT image quality but also increases the exposure dose. Thus, the use of AEC in SPECT/CT contributes to obtaining equal AC SPECT images, and uniform noise in CT images while reducing exposure dose.

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