• 제목/요약/키워드: Air gun

검색결과 486건 처리시간 0.036초

CFD분석을 통한 기류식 분쇄기 날개부의 최적설계 (Optimum Design for an Air Current Pulverizing Blade Using the Computational Fluid Dynamics)

  • 김건회;김한빛
    • 한국기계가공학회지
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    • 제19권8호
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    • pp.8-14
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    • 2020
  • In the air current pulverizing type grinding method, the blade wings fitted inside a casing are rotated at a high speed to generate a cornering air current, which facilitates the collision of materials with one another, leading to the pulverizing phenomenon. In contrast to mechanical grinding, grit pulverizing leads to fine grinding and less acid waste and degeneration of the material. Moreover, this approach prevents the loss of nutritional value, while allowing the milling grain to have an excellent texture. However, the existing air current pulverizing type machines consist of prefabricated blades, which cannot be rotated at a speed higher than 5,000 rpm. Consequently, the grinding process becomes time consuming with a low productivity. To overcome these problems, in this study, the shape and structure of the air current pulverizing type wings were optimized to allow rapid grinding at more than 8,000 rpm. Moreover, the optimal design for the ripening parts for the air current pulverizing type device was determined by performing a computational fluid dynamics analysis based on airflow analyses to produce machinery that can grinding materials to the order of micrometers.

착색단고추 세척기 개발 (Development of a Washing Machine for Paprika)

  • 김영근;윤홍선;최중섭;이영희
    • Journal of Biosystems Engineering
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    • 제36권5호
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    • pp.361-368
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    • 2011
  • The amount of export of paprika has been increased rapidly in recent years. Therefore, its cultivation area has greatly increased in Korea according to current consumer's attraction. Moreover, it becomes one of the major exporting products while it recorded 53 million dollars, in 2009 resulting in 40% of the total vegetables export. Most of the products are exported to Japan, but it is necessary to prolong the quality preservation periods to export paprika to nations like U.S.A. or EU. However, to encourage an export to many countries, washing and disinfection became more important to deal with longer transportation and medical inspection. The non-chemical use is very important due to stronger regulation of safety to agricultural production. Accordingly, this study was performed to determine the optimum conditions and develop a prototype washing machine, hot water washing of paprika. The results were as follows : The working performance of the prototype was 938 kg/hr, and which was 1.5 times higher than the conventional air gun type washing machine. The operation cost of prototype was 30 won/kg, and 56% of the cost was reduced when compared with air gun type washing machine.

풍수(風嗽)의 원인(原因) 증상(症狀) 치법(治法) 치방(治方)에 관(關)한 문헌적(文獻的) 고찰(考察) (The bibliographical study on causing symptom and treatment of wind-coughing ( 風嗽 ))

  • 김락기;오태환;정승기;이형구
    • 대한한방내과학회지
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    • 제12권2호
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    • pp.129-137
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    • 1991
  • This study has been carried out to investigate the cause symptom and treatment of wind-coughing ( 風嗽 ) by referring to 38 literatures. The results were obtained as follows; 1. The factors causing wind-coughing ( 風嗽 ) is wind-air. The 1st factors are mistaking of transport lung-air ( 肺氣不宣 ) and cleaning lung (肺失淸肅). 2. The symptom of wind-coughing ( 風嗽 ) is as follows. Bi Saek Sung Jung ( 鼻塞聲重 ), Gu Gun Hu Yang ( 口乾喉痒 ), A Mi Kung I Hae ( 語未竟而咳 ), Maek Bu ( 脈浮 ), Jeang Han Jang Yul ( 憎寒壯熱 ), Ja Han OU Pung ( 自汗惡風 ), Bun Jo ( 煩躁 ), Bi Ryu Chung Chae ( 鼻流淸?), Ya Jung 11 Jyung ( 夜重日輕 ). 3. The treatment-method of wind-coughing ( 風嗽 ) is as follow. Bal San Bul Ga Ha ( 發散 不可下 ), So Pung San Han ( 疏風散寒 ), Chung Yul ( 淸熱 ), Sun Pae Ji Hae ( 宣肺止咳 ). 4. The treatment-herbs of wind-coughing ( 風嗽 ) is as follow. Kwan Dong Hwa San ( 款冬花散 ), Gun Bi Cho San ( 金沸草散 ), Sam Yo Tang ( 三拗湯 ), Ji Hae San ( 止嗽散 ), Hang So San ( 杏蘇散), Sang Kuk Yeam ( 桑菊飮).

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차륜형 대공포 냉방장치 성능개선 연구 (Study on Improvement of Air Conditioning Units for Anti Aircraft Gun Wheeled Vehicle)

  • 전기현;이동희;이부환
    • 대한기계학회논문집B
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    • 제37권12호
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    • pp.1099-1103
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    • 2013
  • 과거의 무기체계는 체계의 목적과 비용 등의 문제로 운용환경에 대한 관심이 부족하였으며, 특히 냉방장치가 미탑제된 체계가 많이 개발되었다. 근래 개발되는 무기체계는 고도의 정밀조준 및 고감도 시스템으로 진화함에 따라 무기체계를 효과적으로 제어하기 위하여 운용자의 운용환경도 중요한 요소로 대두되고 있다. 현재의 무기개발자들은 대부분 통합형 환경제어장치를 장착하도록 설계하고 있다. 본 연구에서는 장갑차량의 운용환경 및 설계조건을 바탕으로 한국군의 운용환경에 적합한 냉방기 및 냉방 부하를 검토하고 시제품의 냉방성능 시험결과가 목표성능에 미달되어 이에 대해 개선내용 및 검토결과를 기술하였다.

Survey evaluation of thermal boundary condition in the inside and outside of double skin facade

  • Shin, Hyun-Cheol;Jang, Gun-Eik
    • KIEAE Journal
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    • 제15권4호
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    • pp.29-35
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    • 2015
  • Purpose: Double skin facade is a representative advantageous passive technology of building skin in the aspect of energy saving and environment improvement, reduces heat loss with buffer space in winter season and enhances indoor air and comfort of residents by activating natural ventilation in mid-season. However, in summer season, temperature increase in the intermediate space due to solar energy from exterior transparent skin could be a potential problem; also, relatively weak buoyancy of air caused by low density difference between double-skin facade could increase cooling load as air of intermediate space in high temperature hangs. However, proof data is insufficient to objectify such phenomenon. Method: In this study, researchers surveyed air temperature of intermediate space and airflow and diagnosed its cause targeting on applied multistory facade in the building which gives thermal uncomfort to residents. Also, the researchers produced Solar-air heat transfer coefficient meter, measured thermal boundary condition of double-skin facade, and presented the result of measurement as an objectified verification material regarding overheating phenomenon in the intermediate space of double-skin facade in summer season. Result: Inefficient condition was verified that total heat increases and overheating due to insufficient natural ventilation in multistory facade. In addition, logic behind preceding research was objectified and verified regarding high temperature phenomenon in the intermediate space which could increase cooling load in summer season.

학교 건물의 실내공기환경 실태조사 연구 (A Field Survey of Indoor Air Environment of Schools)

  • 정민희;정선미;김미연;김건우;박진철
    • 설비공학논문집
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    • 제19권12호
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    • pp.865-873
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    • 2007
  • Recently there has been more apprehensions about health and environment. Since the concern has been increased, it is realized that students need to study in comfort and clean environment, and plan to study in environmental friendly facilities. Hence it is needed for both indoor air quality performance evaluation and greening facilities in order to plan environmental friendly schools. Accordingly, this study analyzes the indoor air quality throughout field survey of schools to provide preliminary data to develop environmental friendly education facilities. This paper investigates and analyzes indoor environment standards and performances in schools. There will be included 15 existing schools and 5 newly built schools for survey in Seoul and Gyeonggi. Additionally, environmental problems are also investigated and analyzed by occupants' questionnaires through surveys.

ARIMA 시계열 모형을 이용한 제주도 인바운드 항공여객 증가율 예측 연구 - 제주지역 골프장 내장객 현황 데이터를 활용하여 - (Estimating the Growth Rate of Inbound Air Travelers to Jeju with ARIMA Time-Series - Using Golf Course Visitor Data -)

  • 손건희;김기웅;신리현;이수미
    • 한국항공운항학회지
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    • 제31권1호
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    • pp.92-98
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    • 2023
  • This paper used the golf course visitors' data in Jeju region to forecast the growth of inbound air traveler to Jeju. This is because the golf course visitors were proven to bring the highest economic and production inducement effect to the Jeju region. Based on such a data, this paper forecast the short-term growth rate of inbound air traveler using ARIMA to the Jeju until December 2025. According to ARIMA (0,1,0) (0,1,1) model, it was analyzed that the monthly number of golf course visitors to Jeju has been increasing steadily even since COVID-19 pandemic and the number is expected to grow until the end of 2025. Applying the same parameters of ARIMA (0,1,0) (0,1,1) to inbound air travel data, it was found the growth rate of inbound air travelers would be higher than the growth rate of 2019 shortly without moderate variation even though the monthly number of inbound travelers to Jeju had been dropped during COVID-19 pandemic.

비점성 유동을 가정한 포 발사 램제트 추진탄 설계 (Design of Gun Launched Ramjet Propelled Artillery Shell with Inviscid Flow Assumption)

  • 강신재;박철;정우석;권태수;박주현;권세진
    • 한국추진공학회지
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    • 제19권4호
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    • pp.52-60
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    • 2015
  • 최근 군 전력 개편에 따라 1개 군단이 담당해야할 작전 영역이 확대됨에 따라 155 mm 화포체계의 사거리 연장은 중요한 이슈가 되었다. 80 km 이상 155 mm 화포 체계의 사거리를 연장하기 위해 새로 운 시도가 필요하다. 램제트 기관은 공기흡입식 기관으로 고체 연료 로켓에 비해 몇 배 이상 높은 비추력을 제공할 수 있어 같은 연료 무게로 더 멀리 포탄을 투사하는 것을 가능하게 한다. 램제트 기관을 포로 발사할 경우 포구 초속이 약 Mach 3 이므로 추가적인 부스터가 필요치 않다. 특히 고체 연료 램제트 (Solid Fuel Ram Jet, SFRJ)는 어떠한 구동기관이 없어 발사 시 높은 충격을 받는 포탄에 적용하기에 적합하다. 본 연구에서는 155 mm 화포체계를 위한 포발사 램제트 추진탄을 설계하기 위해 비점성 유동을 가정하여 공기 흡입구, 연소실, 노즐을 설계하였다. 설계 변수를 변화시키며 80 km 이상 사거리를 가지며, 고폭탄 탑재 용적을 최대화 할 수 있도록 설계하였다.

대규모 도시개발사업에 대한 대기질 평가 사례 연구 (A Case Study on the Air Quality Impact Assessment for the Large Scale Urban Development)

  • 김상목;이상훈;박근형;우재균;구윤서;김성태;한진석
    • 환경영향평가
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    • 제16권6호
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    • pp.381-391
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    • 2007
  • The air quality modeling was carried out to assess the impact of air quality for large scale urban development. The site for the assessment is Multi-fuctional Administrative City which locates in Yeongi-gun, Chungcheongnam-do and estimated population in 2030 is 500,000. Two automatic weather monitoring stations were installed to monitor the meteorological variables for a year and upper air meteorological parameters were measured using radiosonde for 5 days with 4 hours interval in every season. The air quality of standard air pollutants were also measured for 5 days continuously in every season. The results of wind field analysis based on the site measurements and CALMET modeling showed that the valley and mountain winds were prevailed when the sypnotic wind was weak. It also showed that wind speed and directions were highly space-variable within the site basin. The variable wind characteristics implies that the Gaussian dispersion model such ISC3 and AERMOD are not appropriate and the unsteady-sate Lagrangian model such as CALPUFF is preferable. CALPUFF model was applied to assess air quality impact of new sources. The new sources were those for individual and group heating facilities as well as the traffic increases. The results showed that the estimated concentrations of CO and $SO_2$ pollutants by summing the impact concentration of new sources by the dispersion model and the ambient air concentrations by the site measurements were acceptable but those of PM-10 and $NO_2$ would violate ambient air quality standards at several locations due to high ambient air concentrations. It is recommended that the emission reductions near the site should be enforced to improve the ambient air quality.

주요 딸기주산지에서 이용되는 육묘배지 종류 및 이화학적 특성 (Types and Physicochemical Characteristics of the Nursery Media Used in Major Strawberry-Farming Regions)

  • 박갑순
    • 한국환경과학회지
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    • 제25권6호
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    • pp.889-895
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    • 2016
  • In Danseong-myeon (myeon is a subdivision of), Sancheong-gun, and Sugok-myeon, Jinju City, pot seedling culture was used at the rates of 100% and 62%, respectively. Root restriction seedling culture was used relatively more frequently than pot seedling culture in Yangchon-myeon, Nonsan City, Guryong-myeon, Buyeo-gun, and Wolsan-myeon, Damyang-gun. Open-field seedling culture was used at the rates of 80% and 54% in Samnangjin-eup (eup is a subdivision of a gun), Miryang City and Ssangnim-myeon, Goryeong-gun, respectively. In Danseong, Sancheong, and Sugok, Jinju, granite soil was used as the medium for pot seedling culture at the rates of 90% and 80%, respectively. In Yangchon, Nonsan, Wolsan, Damyang, and Ssangnim, Goryeong, commercial bed soil and coir dust were used for seedling culture at the rates of 73%, 64%, and 60%, respectively. At the main production sites, the use of granite soil for seedling culture, highest rate in 2000-2005, continued to decrease; in 2011-2013, granite soil was used at the rate of 37%, while commercial bed soil and coir dust were used at the rates of 32% and 14%, respectively. The bulk density of commercial bed soil, expanded rice hulls, and coir dust was $0.11-0.16g/cm^{-3}$. Coir dust was the lightest material but had the highest and, 36.7% and 21.8%, respectively. In sandy loam soil and granite soil was low. The pH of all growth media was between 5.4 and 7.0, and the values were in the range of $0.15-0.66dS{\cdot}m^{-1}$. However it was necessary, to adjust the pH levels and enhance the of expanded rice hulls, sandy loam soil, and granite soil. Similarly, the fertilizer concentration and air permeability of coir dust need to be adjusted.