• Title/Summary/Keyword: Air spring

Search Result 840, Processing Time 0.03 seconds

Reproductive Dynamics of the Gold-spotted Pond Frog (Rana plancyi chosenica) Population Located at Cheongwon, Korea (청원군에 소재한 금개구리(Rana plancyi chosenica) 개체군의 번식동태)

  • Sung, Ha-Cheol;Ra, Nam-Yong;Cheong, Seok-Wan;Kim, Soo-Kyeong;Cha, Sang-Min;Park, Dae-Sik
    • Korean Journal of Environmental Biology
    • /
    • v.27 no.1
    • /
    • pp.20-30
    • /
    • 2009
  • To study reproductive dynamics of a Gold-spotted pond frog (Rana chosenica) population located at Gangnae, Cheongwon, Chungbuk, Korea, we monitored the population over 207 days between April 17$^{th}$ 2007 and December 18$^{th}$ 2008 using a drift fence accompanied with 20 pitfall traps. The population was located in an agricultural wetland, compromising three small ponds. Gold-spotted pond frogs immigrated into the wetland between April 16$^{th}$ and June 17$^{th}$ and emigrated from the wetland between September 21$^{st}$ and November 12$^{th}$. Precipitation showed a positive correlation with the number of migrated frogs in Autumn 2007 and Spring 2008, but other environmental factors such as air and water temperatures and relative humidity did not show any significant relationships. In general, small frogs first migrated into and from the wetland, but the trend was not strong. Female gold-spotted pond frogs were bigger than males. During the autumn migration, small frogs of which snout-vent length was smaller than 20 mm were found, indicating that successful breeding occurred in the population. Our results could be useful to conserve this endangered species in Korea.

Ionic composition comparison of atmospheric aerosols at coastal and mountainous sites of jeju island (제주도 해안과 산간 지역 대기 에어러솔의 이온조성 비교)

  • Hong, Sang-Bum;Jung, Duk-Sang;Lee, Soon-Bong;Lee, Dong-Eun;Shin, Seung-Hee;Kang, Chang-Hee
    • Analytical Science and Technology
    • /
    • v.24 no.1
    • /
    • pp.24-37
    • /
    • 2011
  • The ionic compositions of atmospheric aerosols were investigated and characterized in coastal and mountainous sites of Jeju Island, which were Gosan and Mt. Halla-1100 sites respectively. It was found that the concentrations of nss-$SO_4^{2-}$ (non-sea salt sulfate) and $NH_4^+$ at two measurement sites were almost similar and they showed high concentrations in June at the same time. The concentration of soil-originated nss-$Ca^{2+}$ (non-sea salt calcium) was generally associated with that of anthropogenic $NO_3^-$ and its concentration was increased during spring season. From the comparison of time-series variation and regression analysis of ionic species between two measurement sites, TSP (total suspended particulate) in Gosan site was directly influenced by sea salt particles and the concentration levels of nss-$SO_4^{2-}$, $NH_4^+$, nss-$Ca^{2+}$, $K^+$, and $NO_3^-$ were mainly related with long-range transported air pollutants rather than local pollution sources.

Kinetic Analysis of the Salto Side-Ward Tucked on the Balance Beam (평균대 옆공중돌기 동작의 운동역학적 분석)

  • Yeo, Hong-Chal;Chang, Jae-Kwan
    • Korean Journal of Applied Biomechanics
    • /
    • v.18 no.3
    • /
    • pp.61-69
    • /
    • 2008
  • The purpose of this study is to examine the success or failure on the balance beam in element group requirements posture which is bending salto side-ward tucked through kinetic analysis. The national team players were participated. The goal was to present training methods to coaches and athletes so as to provide scientifically useful information. The results from this study were summarized as below. When the performance was successful, the features of the body's center of gravity during the side somersault motion showed to spread from the center of the balance beam and the center of the gravity moved to the direction of the body's rotation. In the spring sections - event2 and 3, when the performance was successful, up/down fluctuation became more wider and increased air time. It supported the result that the projecting variable was higher than in failure trial. In addition, the right side hip joint angles and speed, and angular velocity as jumping up for a leap were larger than in failure trial. Those variables showed the optimal conditions for a leap. By increasing the speed of the upper limb from the shoulder and the speed of the shoulder joint angular velocity, the momentum was increased. Especially the right side shoulder joint angular velocity increased dramatically because the right leg was held. As to the side somersault motion, the angular momentum of successful trial with respect to x-axis was bigger than failed trial. It indicated that the increasing angular momentum with respect to x-axis was an important factor in flying motion. Besides, as to side somersault, the appropriate proportion of angular momentum with respect to y-axis and z-axis was a key to successful trails.

Introduction of Spring Cultivation of Onions by Adapting the Plug Seedling System in the Middle Region of Korean Peninsula (중부지방에서 플러그 육묘에 의한 양파의 춘파재배 가능성)

  • Lee, Jung-Soo;Seong, Ki-Cheol;Sin, Young-An;Ro, Hee-Myong;Um, Young-Cheol
    • Horticultural Science & Technology
    • /
    • v.18 no.1
    • /
    • pp.9-13
    • /
    • 2000
  • Cultivation of onions in Korean peninsula is so restricted to Southern region, mainly due to inadequate air temperature for the growth of onions in this region. This sometimes resulted in unstable supply of onions. The fluctuation of market prices mainly results from the limited production of onions in such restricted areas. Onions are usually transplanted at the end of fall and cultivated until the beginning of next summer. This study was designed to examine the possibility of extending production region of onions by adopting the plug seedling system, and the effects of plug seedling age, transplanting date, plug cell volume, and variety on the yield of onions were investigated. Transplanting date (Mar. 15 or Apr. 15) did not affect the yield of onions. However, 60-day-old seedlings produced significantly greater bulb yield (107.2 ton/ha) than those of 30- or 90- day-old seedlings. Bulb yields of seedlings raised in 128 and 72 cell trays were 125.0 and 120.8 ton/ha, which were significantly greater than those in other cell trays. Yield of seedlings raised in 406 cell trays was the lowest. Seedlings of mid-late 'Chenjuwhang' yielded 130.5 Ton/ha, which was significantly higher than those of other varieties. Considering the rainy season during early summer, we suggest that seedlings of onions raised for 60 days and transplanted on Mar. 15 should be advantageous in producing of marketable bulbs and that an early 'Yongbongwhang' should be the best variety.

  • PDF

Postharvest Handling and Marketing Management for Making High Salability of Sweetpotatoes (상품성 제고를 위한 고구마 수확 후 관리 및 출하기술)

  • Jeong, Byeong-Choon
    • Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
    • /
    • 2001.06a
    • /
    • pp.51-64
    • /
    • 2001
  • The qualities including taste of sweetpotato stored during the winter which can display in the spring market in Korea are affected by availability of storage for the roots. In order to make high storage availability of sweetpotato, the postharvest handlings should be done thoroughly from the moment of harvest until shipping them to the market. A lot of procedures that must be handled carefully for improving postharvest management are as follows; digging, trimming, gathering, putting in storage containers, carrying them from field to house, curing, storing, washing, drying, selecting marketable roots, packing and shipping to the market, etc.. Sweetpotatoes have a high moisture content, and a relatively thin and delicate skin, and are sensitive to chilling, so careless postharvest handling can lead to both quantitative and qualitative losses which may be extremely high in some circumstances. From now on research has concentrated on the improvement of postharvest conditions to increase yield and lower disease rates. Storage, which makes sweetpotatoes available through out the year, benefits both the producer and the consumer. Seven very important points must be needed in order to get the best quality marketable roots in the storing of sweetpotatos : $\circled1$The storage house must be clean and sanitary, $\circled2$The crop must be harvested before the first frost to avoid low-temperature injury, $\circled3$Particular care must be taken to avoid cutting, bruising, or other injuries of the sweetpotatoes during digging, picking up, grading, placing in containers, and moving to the storage house, $\circled4$Select sound, disease-free roots for storage $\circled5$Sweetpotatoes should be stored in properly stacked containers $\circled6$Cure immediately after harvest, preferably at 32∼33$^{\circ}C$ and 90 to 95 percent relative humidity for 4 to 7 days, After curing the temperature should be reduced to 13$^{\circ}C$ to 16$^{\circ}C$ by ventilating the storage with outside air. $\circled7$Store at 12$^{\circ}C$ to 14$^{\circ}C$ and a relative humidity of 80 to 85 percent. Storage houses should be located on suitable sites and should be tightly constructed and insulated so that temperature and humidity will be uniform. Sweetpotatoes are usually not washed and graded, and lately sometimes washed, graded, waxed, before being shipped to market. Consumer packaging of sweetpotatoes in paper boxes(10-15kg) or film bags is done mainly to aid marketing. The shelf life of washed roots in consumer packs in only 1 to 2 weeks. Weight loss of roots during marketing is much less in perforated film bags than in mesh and paper bags. Perforation of 0.8 to 1kg polyethylene bags with about six 6mm holes is essential ; to lower the internal relative humidity and avoid excessive sprouting, rooting, and dampness. Development and use of better postharvest handling with good storage facilities or marketing methods can minimize sweetpotate losses and has an effect of indirectly increasing productivity and farmer’s income.

Temporal and Spatial Distribution of Ambient Sulfur Dioxide Concentration in Forest Areas, Korea (우리나라 산림지역에서의 이산화황 농도의 시.공간적 분포)

  • Seung-Woo, Lee;Lee, Choong-Hwa;Ji, Dong-Hun;Youn, Hee-Jung
    • Korean Journal of Soil Science and Fertilizer
    • /
    • v.43 no.6
    • /
    • pp.1035-1039
    • /
    • 2010
  • For 65 national forest areas in 1993 to 2008, the ambient sulfur dioxide ($SO_2$) concentrations were measured monthly using passive samplers and compared to the those of urban areas in order to investigate the characteristics of temporal and spatial distribution. In the forest areas, annual average concentration of sulfur dioxide gradually decreased from the beginning year of monitoring to 1997 and then had no significant change, such as the annual trend in urban areas monitored by Ministry of Environment. For the monitoring term, average concentration of sulfur dioxide in the forest areas was 5.6ppb, which was lower than the 10.1ppb in the urban areas and the EC ecological standard level (7.6 ppb). Seasonally, both in forest areas and urban areas the monthly average concentrations were much higher in winter and spring due to much more heating fuel consumption, and lowest in summer. Regional comparison to other regions of Gyeongbuk and Gyeonggi province showed that the concentration of sulfur dioxide was the highest during year. A significant positive correlation between sulfur oxides' emissions and sulfur dioxide concentration by province was observed, reflecting that the size and proximity of sources of atmospheric sulfur oxides could be important factors in determination.

A Study on the Ride Quality Enhancement of the High-speed Electric Multiple Unit (동력분산형 고속열차의 승차감 개선에 관한 연구)

  • Jeon, Chang-Sung;Kim, Sang-Soo;Kim, Seog-Won
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.19 no.11
    • /
    • pp.561-567
    • /
    • 2018
  • This study was carried out to improve the ride quality of high-speed electric multiple unit. Through dynamic analysis of the HEMU-430X, the range of the equivalent conicity with a critical speed of 300 km/h was between 0.05 and 0.25. The initial adopted wheel profile of HEMU-430X was S1002. The equivalent conicity of S1002 with the mileage of more than 40,000 km was about 0.033 and it was confirmed that XP55 is more suitable for stable operation because XP55 has the equivalent conicity of over 0.061. In order to improve ride quality of high-speed electric multiple unit, the change of installation angle of the yaw damper was suggested from $7.35^{\circ}$ to $0^{\circ}$. From sensitivity analysis and optimization, the air spring lateral and vertical stiffness was suggested to be reduced by 30% and the secondary vertical and lateral damper damping coefficient was increased by 50%. By applying this, it was expected that the car body acceleration could be improved by about 20% on average. The HEMU-430X's yaw damper installation angle was changed to $0^{\circ}$ and the damping coefficient of the lateral damper was increased by 30%. When the test run was carried out at the speed of 300 km/h on the Kyungbu high-speed line, the vehicle lateral acceleration had improved by 34.3%. The effect of additional improvement measures proposed in this paper will be tested in the on track test. The riding quality improvement process used in this study can be used to solve ride quality problems that can occur in commercial operation of high-speed electric multiple unit in the future.

Changes in the Reproductive Population Size of the Huanren Brown Frog (Rana huanrenensis) and Wonsan Salamander (Hynobius leechii), which Breeding in Mountain Valleys, According to Climate Change (기후변화에 따른 산간계곡에 번식하는 계곡산개구리 (Rana huanrenensis)와 도롱뇽 (Hynobius leechii) 번식개체군 크기의 변동)

  • Choi, Woo-Jin;Park, Daesik;Kim, Ja-Kyeong;Lee, Jung-Hyun;Kim, Dae-In;Kim, Il-Hun
    • Korean Journal of Environment and Ecology
    • /
    • v.32 no.6
    • /
    • pp.582-590
    • /
    • 2018
  • Although there are many studies of the effect of climate change on the breeding phenology and community diversity of amphibians, the studies of variations in reproductive population size of individual species according to climate change are still lacking. We examined the effect of climate change on the reproductive population size of Rana huanrenensis and Hynobius leechii, which bred in mountain valleys, by surveying the reproductive population of the two species between 2005 and 2012 and analyzing the correlation between the variation of the outdoor population and the surrounding climate change factors, obtained from a meteorological observatory located at 5.6 km from the study site. The size of the reproductive population of the two species commonly fluctuated with aan pproximately 3.5-year cycle. That of H. leechii, in particular, decreased significantly over eight years. The air temperature tended to more closely relate with the reproductive population size of R. huanrenensis as was the case of the precipitation with that of H. leechii. The yearly mean highest temperature and spring mean temperature variation consistently decreased over the eight years, and the latter was related with the significantly decreased size of H. leechii reproductive population. These results showed that recent climate change directly could affect the reproductive population size of amphibians, particularly H. leechii, which breeds in mountain valleys.

Prediction and Analysis of PM2.5 Concentration in Seoul Using Ensemble-based Model (앙상블 기반 모델을 이용한 서울시 PM2.5 농도 예측 및 분석)

  • Ryu, Minji;Son, Sanghun;Kim, Jinsoo
    • Korean Journal of Remote Sensing
    • /
    • v.38 no.6_1
    • /
    • pp.1191-1205
    • /
    • 2022
  • Particulate matter(PM) among air pollutants with complex and widespread causes is classified according to particle size. Among them, PM2.5 is very small in size and can cause diseases in the human respiratory tract or cardiovascular system if inhaled by humans. In order to prepare for these risks, state-centered management and preventable monitoring and forecasting are important. This study tried to predict PM2.5 in Seoul, where high concentrations of fine dust occur frequently, using two ensemble models, random forest (RF) and extreme gradient boosting (XGB) using 15 local data assimilation and prediction system (LDAPS) weather-related factors, aerosol optical depth (AOD) and 4 chemical factors as independent variables. Performance evaluation and factor importance evaluation of the two models used for prediction were performed, and seasonal model analysis was also performed. As a result of prediction accuracy, RF showed high prediction accuracy of R2 = 0.85 and XGB R2 = 0.91, and it was confirmed that XGB was a more suitable model for PM2.5 prediction than RF. As a result of the seasonal model analysis, it can be said that the prediction performance was good compared to the observed values with high concentrations in spring. In this study, PM2.5 of Seoul was predicted using various factors, and an ensemble-based PM2.5 prediction model showing good performance was constructed.

Changes in Light Transmittance of Greenhouse Covering Materials and Cucumber Growth as Affected by Particulate Matter (미세먼지 발생에 의한 온실 피복재의 광투과율 감소 및 오이 생육 변화)

  • Inseo Hong;Yoomin Ha;Yurina Kwack
    • Journal of Bio-Environment Control
    • /
    • v.32 no.4
    • /
    • pp.312-318
    • /
    • 2023
  • In recent years, fine and yellow dust pollution has become serious in Korea and has negatively affected crop production. Particulate matter (PM) adheres to greenhouse coverings, and it reduces the amount of solar radiation transmitted into a greenhouse. A reduction in light transmittance can have a direct effect on crop photosynthesis and an indirect effect on air temperature in a greenhouse, which can lead to differences in crop yield. The objectives of this study were to investigate the changes in light transmittance of different cover materials by PM and to determine the changes in cucumber growth in a greenhouse due to reduced light transmittance. We measured the changes in light transmittance of polyethylene (PE) and polyolefin (PO) films in the PM generation chambers. Also, cucumber plants were cultivated in a greenhouse with four different light reduction treatments (0, 10, 20, and 30% reduction of light transmittance). The initial light transmittance of PO film was higher than that of PE film and the decrease in light transmittance of PO film due to PM was less than that of PE film. The vegetative growth of cucumber was promoted under the reduced light transmittance treatments; however, the yield of cucumber was highest in the control (0% reduction of light transmittance). From the results, we confirmed that PO film was less PM adhesion and that cucumber yield during the spring season can be reduced by the reduction in light transmittance due to PM.