• Title/Summary/Keyword: DO meter

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Effects of Civil Blasting on Noise, Vibration and Total Suspended Particles (토목 발파가 소음, 진동, 부유 분진에 미치는 영향)

  • Jeong, Jin Do;Jeong, Yeong Guk
    • Journal of Environmental Science International
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    • v.13 no.1
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    • pp.99-107
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    • 2004
  • This research is to determine the level of environmental pollution at a blasting construction area which is the origin of noise, vibration, and suspended particle, and to compare the results with other domestic and international standard data. This experiment is also to find out the effects resulting from blasting construction and to propose a plan that can decrease environmental pollution. The blasting construction area is a factory site which is about one and half million square meter and sewage disposal plant is about ninety thousand square meter. Both were selected as the areas for the tests to be conducted in determination test. The test to determine the level of noise, vibration, and total suspended particle was conducted thirty times around the blasting construction area by comparing measurement results and numerical analysis. However, as the test was not conducted in the laboratory but in the actual blasting construction area, it was not possible to do the test with the same exact conditions each true. Therefore, the test was not ideal as conditions could change from test to test. For the most part, the level of noise was below the standard level of 70dB. Every vibration test was under the standard limitation. For example, a house, 200m away was tested for noise and vibration and the level was found to be under the 0.2 cm/sec which is the standard for specialty designed cultural sites., i.e very low level. Also a buried oil pipeline that was 30m away also marked under 2.0cm/sec which is the norm for an industrial area. However, if there were an oil pipeline under the house, the amount of charging gunpowder per hole should be decreased compared to the amount used in the test. The test result for suspended particles under the standard limitation which is 24hour average 300$\mu\textrm{g}$/㎥ at a distance from blasting wavelength, but at detonator, total suspended particle from the blast origin exceeded the standard limitation. If explosion occurs when it detonates in the hole, most of the energy would be absorbed in the crushing of rocks, but some remaining energy would make noises and vibration inevitable. So the important thing is how to minimize the environmental pollution from the blasting. There should be regulations in order that the standard limitation is not exceeded, and to decrease the environmental pollution from the blasting.

THE INDIVIDUAL PRODUCTION RATE OF PLECOGLOSSUS ALTIVELIS IN GANGJEONG STREAM, JEJU-DO IN SUMMER (강정천산 은어, Plecoglossus altivelis의 하계개체생산속도에 대하여)

  • KIM Eul-Bae
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.7 no.4
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    • pp.195-203
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    • 1974
  • The individual production rate of Plecoglossus altivelis was studied from the 18th of June to the 25th of September (99 days) 1973, when the fish grow best at Gangjeong Stream, Jeju Do, as one of the ways to find out the reasons why the size of P. altivelis of Jeju Island is smaller than that of other places. The results obtained are as follows : 1) The indivudual production rate of the fish in the Gangjeong Stream during the summer 1973, was estimated as shown in Table 6. 2) The individual production rate of the fish and standing crop of algae on stones in the Gang-jeon Stream were no more than $7.2\%$ and $6.2\%$ respectively, when compared with those of the Ukawa River (which is located in Japan), thus the individual production rate of the fish at Gang-jeong Stream being very poor. 3) Population density was 5.2 individuals average per square meter during the research period. This is beyond the estimated density limit, i. e., 4.8 individuals per square meter, for the standing crop of algae on stones. 4) The period that the individual production rate of the fish was the most brisk during the summer in this stream was from August to September in 1973. 5) The poor individual production rate is primarily regarded due to insufficient gross ingestion. The reasons seemed to be insufficeient productivity of algae on the bottom stones, over-population density of the fish, and the lowered activity of ingestion due to low water temperature in daytime as compared with other places. Thus, the production rate of Plecoglossus altivelis in the Gangjeong Stream during the summer was greatly influenced by these factors.

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A Study on the Status of Supply-Demand and Procurement of the Timber for Wooden Cultural Properties (문화재용(文化財用) 목재(木材)의 수급(需給) 및 유통(流通) 실태(實態))

  • Bae, Jae Soo;Kim, Wae Jung;Park, Kyung Seok;Baik, Eul Sun
    • Journal of Korean Society of Forest Science
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    • v.89 no.1
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    • pp.126-134
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    • 2000
  • The purpose of this study is to examine the status of supply-demand and procurement of the timber used for wooden cultural properties. Because people require the high quality pine timber with cultural assurance and public function for cultural properties, it is priced far higher than ordinary construction timber. The timber consumption was estimated at 18 thousand cubic meter in 1998, of which the large sized log(LSL) with the small end diameter over 30cm consisted of 35.5%, equivalent to 6,300 cubic meter. Majority of the timber was supplied from private forest located in Kangwon-do and national forest, accounting for 65.7% and 16.7%, respectively. Recently the supply more and more relied on timber logged in Kangwon-do. Owing to lack of domestic supply of LSL class timber, part of the volume has been substituted by import log. Most of carpenters working on cultural properties thought that supply of LSL timber would hardly meet the increasing demand for uses of wooden cultural properties. Finally, in order to uphold the tradition of wooden cultural properties, it is necessary to establish a forest management plan which aim at producing large size high quality pine timber.

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Sod Production in South Korea (한국의 잔디 생산 현황)

  • Choi, Joon-Soo;Yang, Geun-Mo
    • Asian Journal of Turfgrass Science
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    • v.20 no.2
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    • pp.237-251
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    • 2006
  • This study was carried out to provide data on current sod production in South Korea. Fifteen items were surveyed including production acreage, species and cultivars, experience on farming, production cost and the others during April to October in 2006. To estimate production acreage, 73 turfgrass growers were interviewed. Estimated acreage for turfgrass production was 2,947 ha. Acreages by province were 1,417 ha in Jeollanam-do(48%), 442 ha in Jeollabuk-do(14.9%), 344 ha in Gyeonggi-do(11.6%), 248 ha in Gyeongsangnam-do(8.4%), and 240 ha in Chungcheongnam-do(8.1%), respectively. The major sod producing regions were Jangseong-gun, Hampyeong-gun, Yeonggwang-gun, Gochang-gun, Sacheon city, Iksan city, Yeoju city, Yeoncheon-gun. Percentage of turf growers over 50 years old was 72.4 percent, which means production was carried out mainly by old farmers. Grower's career over 10 years was 84.8%. Cultivated species and varieties were 'Junggi'(55.5%) of fine-textured Korean lawngrass, common Korean lawngrass(37.4%), Kentucky bluegrass(3.8%), and new zoysiagrass cultivars(0.1%), respectively. Sod size were variable. Sod size of $18{\times}18cm $ was 43.5 percent. Sales route was mainly through sod distributor(40.5%). Sod producing cost was $2,160{\sim}2,730$ won per square meter at Jeolla-do areas.

PERFORMANCE OF THE TRAO 13.7-M TELESCOPE WITH NEW SYSTEMS

  • Jeong, Il-Gyo;Kang, Hyunwoo;Jung, Jaehoon;Lee, Changhoon;Byun, Do-Young;Je, Do-Heung;Kang, Sung-Ju;Lee, Youngung;Lee, Chang Won
    • Journal of The Korean Astronomical Society
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    • v.52 no.6
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    • pp.227-233
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    • 2019
  • We report the performance of the 13.7-meter Taeduk Radio Astronomy Observatory (TRAO) radio telescope. The telescope has been equipped with a new receiver, SEQUOIA-TRAO, a new backend system, FFT2G, and a new VxWorks operating system. The receiver system features a 16-pixel focal plane array using high-performance MMIC preamplifiers; it shows very low system noise levels, with system noise temperatures from 150 K to 450 K at frequencies from 86 to 115 GHz. With the new backend system, we can simultaneously obtain 32 spectra, each with a velocity coverage of 163 km s-1 and a resolution of 0.04 km s-1 at 115 GHz. The new operating system, VxWorks, has successfully handled the LMTMC-TRAO observing software. The main observing method is the on-the-fly (OTF) mapping mode; a position-switching mode is available for small-area observations. Remote observing is provided. The antenna surface has been newly adjusted using digital photogrammetry, achieving a rms surface accuracy better than 130 ㎛. The pointing uncertainty is found to be less than 5" over the entire sky. We tested the new receiver system with multi-frequency observations in OTF mode. The aperture efficiencies are 43±1%, 42±1%, 37±1%, and 33±1%, the beam efficiencies are 45±2%, 48±2%, 46±2%, and 41±2% at 86, 98, 110, and 115 GHz, respectively.

Design of Micro-meter Position Driver for X-Y Stage Using Linear Ultrasonic Motor (리니어 초음파 모터를 이용한 X-Y stage의 마이크로 미터급 위치 구동회로 설계)

  • Kim, Jeong-Do;Hong, Chul-Ho;Kim, Dong-Jin;Ham, Yu-Kyung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.6 no.2
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    • pp.165-171
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    • 2005
  • The ultrasonic piezo motor is a new type motor that has an excellent performance and many useful features that electromagnetic motors do not have. But, it suffers from severe system non-linearities and parameter variations especially during speed control. Therefore, it is difficult to accomplish satisfactory control performance by using the conventional PID controller. In this paper, to achieve the precise control for linear type ultrasonic motor was analyzed as a function of response time and change with a driving time. Also, we propose controller that combines STEP controller and PD controller that have error of ${\mu}m$ about liner type ultrasonic motor.

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Biological Control of Bradysia difformis using the Predatory Mite (Hypoaspis aculeifer) in Hydroponically Cultivated Strawberry (수경재배 딸기에서 포식성 천적, 아큐레이퍼응애를 이용한 작은뿌리파리의 생물적 방제)

  • Kim, Hyeong-Hwan;Yoon, Jung-Beom;Kim, Dong-Hwan;Yang, Chang-Yeol;Kang, Taek-Jun
    • Korean journal of applied entomology
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    • v.55 no.4
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    • pp.489-494
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    • 2016
  • Biological control of the fungus gnat Bradysia difformis by the predatory mite Hypoaspis aculeifer was examined in hydroponic systems of strawberries in Namwon and Hapcheon varieties of Jeollabuk-do and Gyeongsangbuk-do provinces, respectively, from 2012 to 2013. The damage to strawberries caused by B. difformis was examined in seedling stages and during cultivation periods. To achieve environment-friendly management of B. difformis, 60.6 individuals of H. aculeifer were released per square-meter three and four times during cultivations periods of the Namwon and Hapcheon strawberry varieties, respectively. H. aculeifer had better control efficiency against of B. difformis than that observed with conventional cultural practices. Wilt symptoms and damage of strawberries due to B. difformis were decreased by approximately 7.4-10.4%.

양식참굴의 PAHs 노출에 대한 생리적 적응

  • 서종환;조상만;정우건
    • Proceedings of the Korean Aquaculture Society Conference
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    • 2003.10a
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    • pp.46-146
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    • 2003
  • 해양환경의 대표적 오염물질인 PAHs가 양식굴의 생리대사에 미치는 영향을 파악하고자, 서로 다른 PAHs 농도에 노출된 굴의 여수율, 호흡율, 배설율 및 동화율의 변화를 조사하였다. 부착생물을 깨끗하게 제거한 굴을 실험실로 옮겨 3일정도 순치시키고, 이후 각각의 0, 50, 100, 200ppb의 농도별로 약 10일간 미리 노출시켰다. 이후 각 개체별로 2L 들이 2$0^{\circ}C$항온수조에서 0.2$\mu\textrm{m}$ 여과해수를 사용하여 실험하였다. 여수율은 Chaetoceros simplex를 지표생물로 하여 수조내 시간당 감소율을 구하여 Kim(1995)의 식에 의해 구하였다. 호흡율은 유동파라핀으로 외부와의 공기접촉을 단절시키고, 수조내 단위시간당 DO meter로 산소변화를 측정하여 Widdows and Johnson(1988)의 식을 변형하여 계산하였다. 배설율은 단위시간동안 수조내 NH$_4$-N 농도 증가량으로 조사하였고, NH$_4$-N은 HACH Inc.에서 제공하는 측정법을 따랐다. 여수율은 500ppb에서 다소 영향을 받아 증가하였다. 호흡율과 배설율은 노출농도가 증가함에 따라 증가하였지만, 50ppb와 100ppb에서는 다소 차이가 없었다. 따라서 양식굴이 PAHs와 같은 오염물질에 노출되었을 경우, 초기에는 여수율의 변화는 없고 배설율과 호흡율이 상승하여 체내 에너지 요구량이 증가하는 것으로 생각된다.

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Analysis of Temperature and Total Heat of Heated Glass through Experimental Measurement and Three-Dimensional Steady-State Heat Transfer Analysis (실측실험과 3차원 정상상태 열전달 해석을 통한 발열유리의 온도 및 전열량 분석)

  • Lee, Do-Hyung;Yoon, Jong-Ho;Oh, Myeong-Hwan
    • KIEAE Journal
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    • v.15 no.1
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    • pp.111-116
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    • 2015
  • Heat loss from windows and condensation occuring on its surface due to its lower insulation value causes much discomfort to occupants. In this study, Heated glass was used to make a basic study on prevention of condensation on glass surface for its heating functionality through experimental measurement and simulation analysis of total heat flux on the interior and exterior surface of glass. Error between experimental results and three dimensional steady-state heat transfer analysis were caused firstly, beacuse in the experimental chambers, cold chamber and steady temperature and humidity chamber, air temperature setting was not constant but rather ON/OFF control, and secondly, due to error rate in heat flux meter due to heat flux direction even in stable conditions.

Effects of nitrogen fertigation on cucumber growth and nitrate in Soil under plastic film house (시설재배지에 질소관비 농도가 오이생육과 질산태 질소에 미치는 영향)

  • Kang, Seong Soo;Kim, Myung Sook;Kong, Myung Seok;Kim, Yoo Hak;Oh, Taek-Keun;Lee, Chang Hoon
    • Korean Journal of Agricultural Science
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    • v.41 no.4
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    • pp.385-390
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    • 2014
  • To evaluate the impact of nitrogen fertigation on crop growth and $NO_3$-N concentration in the soil solution, field experiment for cucumber cultivation during spring and fall season were carried out in on-farm located in Byeongcheon-myeon, Chunan-si, Chungcheonnam-do. Supplying nitrogen of 120-150 mg/L by fertigation device into soil per week reached to maximum yields of cucumber fruits. However, cucumber growth did not show any significant difference between nitrogen levels. Nitrogen supply of 400 mg/L, highest N levels, did not affect cucumber growth. Difference between green values of cucumber leaves using RGB scores were closely related with cucumber yields, and therefore, this results suggests that green values of cucumber leaves could be used as a way of determining the application rates of nitrogen for cucumber cultivation period under fertigation system.