• Title/Summary/Keyword: Chamber experiment

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The Comparison of Image Quality between Computed Radiography(CR) and Direct Digital Radiography(DDR) which Follows the Proper Exposure Conditions in General Photographing under the Digital Radiography(DR) (Digital Radiography 환경하에서 일반촬영시 적정 노출조건에 따른 CR과 DDR의 Image Quality 비교)

  • Kim, Jin-Bae;Kang, Chung-Hwan;Kang, Sung-Jin;Park, Soo-In;Park, Jong-Won;Kim, Yeong-Su;Kim, Seung-Sik
    • Korean Journal of Digital Imaging in Medicine
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    • v.5 no.1
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    • pp.64-77
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    • 2002
  • DR has had an important fact not only in the department of radiology but also in productivity or work efficiency of a whole hospital. The environment of DR has more various parameter than CR, so it is able to supply high quality of medical services. The current environment of radiology department in each hospital has been changed from Film-Screen system to DR through Full-PACS. This hospital which uses Full-PACS became to study the proper condition of CR and DDR and how the image quality of them is expressed among general photographing systems in the DR environment. From this experiment, the image quality of DDR is better than CR under the same exposure condition. And in the DDR system, the score of image which uses AEC is a little higher than the score which doesn't use it. Especially it can be known that the function of AEC of DDR is useful to improve the image quality in the part of skull and chest. (The function of AEC : It is the tool that detects the ionized current of x-ray which goes through objects with using the ion chamber which is in the detector. Also it controls the examination of X-ray when the proper density is reached.) Because the proper degree of density can be represented by this system, the photographing can be taken much easily without consideration of the exposure condition with the thickness of various objects. From the result of this experiment, it can be known that the selection of proper exposure condition plays an important rule to gain good Image Quality. More researches will be necessary about DDR system which has potential ability in the future.

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Seeding of the Woody Plants for the Quick-coverage of the Slopes (비탈면 조기수림화를 위한 녹화용 식물의 활용에 관한 연구)

  • Kim, Namchoon;Yoon, Jungseo;Bae, Sunwoo;Son, Won-Ju;Jung, Sungchul
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.5 no.6
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    • pp.72-85
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    • 2002
  • This study was conducted to investigate the germination rates and ground coverage rates of the 16 native wild flower, herbaceous, shrub and woody plants according to temperature and seeding timing for the revegetation and rehabilitation of the roadside slopes. Also, this study was conducted to suggest design criteria to select revegetation plants and to decide proper seed mixture for ecological restoration of the disturbed manmade slopes as a environmentally friendly construction. The results are summarized as follows. 1. Most of the plants germinated after 10~14 days. Woody plants germinated more slowly than wild flowers and herbaceous plants because of the hard seed. 2. Most of the plants showed the highest percentage of the germination rates under $15/25^{\circ}C$ temperature. The next was in order of under the $20/30^{\circ}C$ temperature, normal temperature(October) and $25/35^{\circ}C$ temperature. 3. At the chamber experiment, the Sorbaria sorbifolia var. stellipila showed the highest germination rates. Most of the native wild flowers germinated well and showed high germination rates under the various temperature. 4. As the field germination experiments, the seeding at August shows higher germination rates than that of the seeding at September, but showed lower surviving percentage of the germinated seedlings and lower ground coverage percentage than those of the seeding at September. After one year, Chionanthus retusus, Acer palmatum, Albizzia julibrissin are germinated and showed 10% coverage rates. So, they can be used as revegetation plants for the restoration works. 5. As seed mixture experiment, it was not effective only to increase the proportion of the ratio of the tree seeds, relatively high price, for making woody vegetation. It would be more successful to make vegetation structure by natural competition among wild flowers, shrubs and trees. 6. The excessive dominance of trees in revegetation works may destroy the lower layer of vegetation and it will be undesirable on the species diversity. It is more important to recover the species diversity of the plant community by seed mixture with the considering the germination, the growth characteristics and the correlation effect among revegetation plants. 7. To recover the manmade slopes quickly, increasing the ratio of the wild flower was recommended.

Application of Cyclone to Removal of Hot Particulate in Hot Cell (Hot Cell 내의 고방사능 분진 제거를 위한 사이클론 적용 실험)

  • Kim Gye Nam;Lee Sung Yeol;Won Hui Jun;Jung Chong Hun;Oh Won Zin
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.3 no.1
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    • pp.67-75
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    • 2005
  • The size and main ingredient of hot particulate generated during the nuclide experiment in hot cells of nuclear facilities were 0.5300 $\mu$m and UO$\_2$. A cyclone filter equipment which consists of a cyclone and Bag/HEPA filter was devised to remove hot particulate generated during the nuclide experiment in hot cells of nuclear facilities. The experimental conditions to maximize the collection efficiency of hot particulate were suggested through experiments done with the cyclone filter equipment. With the large size of simulated particulate, the collection efficiency of the particulate was high. When the size of simulated particulate was more than 5 $\mu$m, the collection efficiency of the particulate was more than $80\%$ and when the size of simulated particulate was less than 1.0 urn, the collection efficiency decreased by less than $70\%$. If the inflow velocity of simulated particulate was increased, the collection efficiency of the particulate was also increased. When the inflow velocity of simulated particulate was more than 12m/sec, the collection efficiency was higher than $70\%$, but after 17 m/sec inflow velocity, no change observed. The collection efficiency of the simulated particulate can be enhanced with the length of vortex finder inside the chamber. With the length of vortex finder, 7.2cm, the observed collection efficiency of the particulate was the maximum. Moreover, when the sub-cone was attached under the cyclone, the collection efficiency of cyclone increased $2\%$. It was found that effect by attachment of sub-cone was not serious.

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Combined Effect of Vibration Intensity, Grip Temperature, Noise and Pushing Power on Grip Forces and Skin Temperatures of Fingers (수지진동에서의 진동강도, 손잡이온도, 소음 및 미는 힘의 복합효과에 따른 악력 및 지단피부온의 변화)

  • Koh, Kyung-Sim;Griefahn, B.;Fritz, M.;Brode, P.
    • Journal of Preventive Medicine and Public Health
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    • v.27 no.4 s.48
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    • pp.763-776
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    • 1994
  • Recent studies reveal that grip forces during the hand-arm vibration are most significant for the genesis of vibration-induced white linger syndrome. Therefore, exerted grip forces and skin temperatures of fingers were regarded as dependent variables in experiments and the effects of grip temperature, noise, pushing force, vibration and the combined effect of vibration and pushing force were studied. The objectives of the present study were, first, to varify and compare the changes of grip force affected by grip temperature, noise, pushing force, vibration and the combined effect of vibration and pushing force and, second, to observe the reaction of finger skin temperature affected by above factors. Forty-six healthy male students ($25.07{\pm}2.85$) participated in five systematically permuted trials, which endured 4 minutes each other. Experiments were executed in a special chamber with an air temperature of 21C. In each experiments, the subjects were exposed to five experiment types: (1) grip force of 25N only, (2) pushing force of 50N, (3) acceleration of vibration $7.1m/sec^2(z-direction)$, (4) pink noise of 95 dB (A) and (5) combination of pushing force 50N and acceleration of vibration $7.1m/sec^2$. A repeated-measures analysis of variance (ANOVA) was performed on the grip force to test whether it was affected by noise, pushing force, vibration and pushing force. The present results show that vibration was significantly related to the increase of grip force, but the other factors, such as pushing force, noise and grip temperature had no signigicant influence on the increase of grip force, and that the reaction of finger skin temperature were significantly affected by the skin temperature at start of experiment and grip temperature, not grip force and other experimental conditions. Therefore, we suggest that the management for decreasing the grip force is meaningful to prevent the occurrence of Hand-arm vibration syndrome (HAVS).

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Effects of Temperature, Seed Water Content and Osmoconditioning on Germination and Seedling Elongation of Soybeans (온도.종자수분함량 및 삼투처리가 콩의 발아 및 묘신장에 미치는 영향)

  • Rak Chun, Seong;Many C., Minor;Eun Hi, Hong
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.31 no.4
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    • pp.447-453
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    • 1986
  • Germination and seedling elongation of soybeans [cult. ‘Williams’] were measured at two temperatures (15 and 3$0^{\circ}C$), three seed water contents (30, 50, and 70%), and with and without polyethylene glycol-8000 (PEG) treatments. A split-plot design was used with four replications. Observations were made from two hours to eight days for each treatment combination. Seeds were soaked with 30% PEG solution with 0.2% thiram at 15 C for six days, rinsed with deionized water and dried at 25.5$^{\circ}C$ for three days. Ten treated or untreated seeds were placed on Whatman No. I (9 cm) filter paper in plastic petridishes to which sufficient deionized water was added to adjust seed moisture content to the desired level. The dishes were then sealed with parafilm and placed in a continuous programmed temperature chamber under dark condition. Seedling growth did not occur at either temperature when moisture content was 50 percent or less. Osmo-conditioning with PEG showed positive effects on seedling moisture uptake and seedling growth at 15$^{\circ}C$ but little effect at 3$0^{\circ}C$. Seedling moisture content increased rapidly early in the germination period and reached 60% at 15 C for 56 hours and at 3$0^{\circ}C$ for 28 hours. Seedling growth started when seed moisture reached a critical point of 60% at 15$^{\circ}C$, however, growth started after 20 hours of germination at 3$0^{\circ}C$. Seedlings of soybeans elongated more than four times faster at 3$0^{\circ}C$ than at 15$^{\circ}C$. Water uptake during germination was characterized by two phases in this experiment.

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Lithoautotrophic Nitrogen Removal from Ammonium-rich Wastewater in Aerobic Upflow Sludge Bed(AUSB) Reactor (호기성 상향류 슬러지상 반응조를 이용한 고농도 암모늄 함유폐수의 독립영양 질소제거)

  • Ahn, Young-Ho;Choi, Hoon-Chang
    • Journal of Korean Society of Environmental Engineers
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    • v.28 no.8
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    • pp.852-859
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    • 2006
  • The novel microbial process such as Anammox(anaerobic ammonium oxidation) and Canon(completely autotrophic nitrogen removal over nitrite) processes is promising biotechnology to remove nitrogen from ammonium-rich wastewater like anaerobic sludge digester liquid. In this research, a new Canon-type nitrogen removal process adopting upflow granular sludge bed type configuration was investigated on its feasibility and process performance, using synthetic wastewater and sludge digester liquids. Air as an oxygen source was provided in an external aeration chamber with flow recirculation. In the first experiment using the synthetic wastewater(up to 110 mg $NH_4$-N $L^{-1}$), the ammonium removal was about 95%(92% for T-N) at effective hydraulic retention time(HRT) for 3.8 days. In the second experiment using the sludge digester liquids($438{\pm}26$ mg $NH_4$-N $L^{-1}$), the total nitrogen removal was $94{\pm}1.7%$ at HRT for 5.4 days and $76{\pm}1.5%$ at HRT for 3.8 days, respectively. Little nitrite and nitrate were observed in the effluent of both experiments. The process revealed quite a lower oxygen($0.29{\sim}0.59$ g $O_2$ $g^{-1}N$) and less alkalinity($3.1{\sim}3.4$ g $CaCO_3$ $g^{-1}N$) consumption as compared to other new technology in microbial nitrogen removal. The process also offers the economical compact reactor configuration with excellent biomass retention, resulting in lower cost for investment and maintenance.

Preliminary study on absorption characteristic of a human body according to the amount of clothing worn for developing standard test dummy (표준더미 개발을 위한 착의량에 따른 인체의 흡음특성 기초연구)

  • Kim, Yong-Hee;Lee, Sung-Chan
    • The Journal of the Acoustical Society of Korea
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    • v.36 no.4
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    • pp.254-260
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    • 2017
  • The purpose of this study is to evaluate the sound absorption characteristics of a human body according to the amount of clothing worn by using reverberation method measurement method for developing standard test dummy, which can be used for testing absorption of occupied audience chair. Test method was based on the previous study (Conti et al., 2004), each experiment is conducted in the reverberation room and a subject wearing clothes is standing in that chamber. In this experiment, the sound absorption area of each frequency band according to the wearing of various material clothing was measured. As a result of measurements, the average sound absorption area of the whole frequency band was $0.25m^2-0.48m^2$ in case of a subject not wearing outer clothes, and $0.38m^2-0.98m^2$ in case of wearing of outerwear. Polyester tops by showing the maximum value, the highest characteristics in the 800 Hz to 1 kHz band among the rest of fiber materials. The outer jacket made of the wool and cotton materials show a higher absorption area as the frequency increases to the higher frequency band. The change of the sound absorption area according to the clothing amount was divided by the thermal resistance (clo) of the worn clothes and the weight per body surface area.

Studies on The Reduced Pressure Storage of Fruits( I ) -Comparision of The Reduced Pressure Storage to The Other Storages for The American Summer Pairman- (과실의 감압저장법에 관한 연구( I ) -감압저장과 타 저장과의 비교(축)-)

  • Kim, K.S.;Park, Y.T.;Hong, S.Y.;Sohn, T.H.
    • Applied Biological Chemistry
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    • v.11
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    • pp.67-76
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    • 1969
  • The reduced pressure storage of apple, American Summer Pairman, was investigated comparing with the other storage methods and the following results were obtained. 1. The reduced pressure storage was better to extend the storage life and freshness of apples than the controlled atomoshere storage. 2. Decreasing the pressure of chamber atmosphere to about 20 cmHg showed the best result among several pressure conditions. 3. As for the surface treatment of the apples, poly-ethylene film wrapping showed to be the most favorable method in a short-term experiment. In a long-term experiment, however, poly-ethylene film wrapping seemed to cause apples rot. Poly-vinyl acetate coating seemed to keep the apples from color changing, but it caused an unpleasant odor and a peculiar taste. No significant effect was observed in Gibberellin. 4. Total sugar and reduced sugar of apples were decreased after a certain period of increasing. Acid and Vitamin C, however, gradually decreased from the beginning of storage.

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A Study on the Evaluation Method of Soil Treatment Termiticide (흰개미 토양처리제 효과 평가 및 시험방안 연구)

  • Im, Ik Gyun;Jeong, Seon Hye;Chung, Yong Jae
    • Journal of Conservation Science
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    • v.35 no.2
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    • pp.177-186
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    • 2019
  • A Termiticide that is applied to the soil treatment method, one of the methods for preventing termites in Korea's wooden cultural properties, will be subjected to the leaching of the effective ingredient in treated soil by the moisture behavior of rain. As a result, termiticide is deteriorated and needs to be reprocessed, but the standards and evaluation methods are nonexistent in korea. Accordingly, a basic indoor evaluation measure was proposed for the evaluation of the effectiveness of the termiticide chamber and the calculation of the reprocessing period. First, avoidance and contact toxicity were assessed at two concentrations of the same termiticide as a method for assessing termiticide suitability. The evaluation of mortality revealed that the soil termiticide used in this experiment was non-repellent, and that death from contact was confirmed. Afterwards, artificial rainfall and soil penetration tests were conducted to determine efficacy of termiticide in soil and the approximate reprocessing period was calculated by comparing the weather data. Persistence evaluation revealed perforation by termites after continuous water exposure of more than about 160 to 170mm of water injection condition. Based on the results, compared with weather data for the last five years, the termiticide of concentration used in this experiment is expected to remain effective for about one year if treated after September. The purpose of this study was to provide basic data for the establishment of a manual for the selection of termiticide for soil treatment by calculating the efficacy for termite mortality and the duration of the leaching effectiveness by water behavior in soil.

Improvement in flow and noise performance of backward centrifugal fan by redesigning airfoil geometry (익형 형상 재설계를 통한 후향익 원심팬의 유동 및 소음성능 개선)

  • Jung, Minseung;Choi, Jinho;Ryu, Seo-Yoon;Cheong, Cheolung;Kim, Tae-hoon;Koo, Junhyo
    • The Journal of the Acoustical Society of Korea
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    • v.40 no.6
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    • pp.555-565
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    • 2021
  • The goal of this study is to improve flow and noise performances of existing backward-curved blade centrifugal fan system used for circulating cold air in a refrigerator freezer by optimally designing airfoil shape. The unique characteristics of the system is to drive cold airflow with two volute tongues in combination with duct system in a back side of a refrigerator without scroll housing generally used in a typical centrifugal fan system. First, flow and noise performances of existing fan system were evaluated experimentally. A P-Q curve was obtained using a fan performance tester in the flow experiment, and noise spectrum was measured in an anechoic chamber in the noise experiment. Then, flow characteristics were numerically analyzed by solving the three-dimensional unsteady Navier-Stokes equations and noise analysis was performed by solving the Ffowcs Williams and Hawkins equation with input from the flow simulation results. The validity of numerical results was confirmed by comparing them with the measured ones. Based on the verified numerical method, blade inlet and outlet angles were optimized for maximum flow rate using the two-factor central composite design of the response surface method. Finally, the flow and noise performances of a prototype manufactured with the optimum design were experimentally evaluated, which showed the improvement in flow and noise performance.