• Title/Summary/Keyword: 중량 관리

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Initial Imperfection and Axial Strength of Struts with Octagonal Hollow Section fabricated from HR Plate (열연강판 팔각강관 버팀보의 초기편심과 축방향 압축강도)

  • Jo, Jae Byung
    • Journal of Korean Society of Steel Construction
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    • v.27 no.1
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    • pp.23-30
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    • 2015
  • Developed in this study were Octagonal-hollow-section(OHS) struts, whose compressive strengths against flexural and local buckling is higher than H-shape or rectangular-hollow-section(RHS) struts with the same unit weight. OHS members are also advantageous in handling and storing compared to circular hollow sections(CHS). OHS members were fabricated from HR Plates by cold forming and fillet welding. 5 numbers of 20m long OHS struts were assembled, each of which consist of two 9.6m long OHS member and two end connection elements made of cast iron. The compressive strength of the OHS strut was evaluated by comparing the test results, design codes and FEM analysis each other. Test results show that all of the struts have almost same or larger compressive strength than Korean Road Bridge Design Code(KRBDC) (2012). The initial imperfections can be estimated by using measured strains and are turned out to be less than L/450 for all the struts tested. The results of FEM analysis show that the variation of initial imperfection has less effects on the compressive strength for struts with vertical surcharge than for those with self-weight only, while the strength decreases as the initial imperfection increases. As the result of this study, the allowable initial imperfection for 20m long OHS struts is recommended to be less than L/350 on job sites.

Performance Estimation of Hexagonal Rockfall Protection Net by Numerical Analysis (수치해석을 이용한 육각 낙석방지망의 성능 평가)

  • Oh, Sewook;Park, Soobeom;Kwon, Youngcheul
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.11
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    • pp.53-59
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    • 2014
  • It has been generally recognized that the conventional rockfall protection nets have several problems to actual field application in the aspect of shock absorption, lack of pullout bearing capacities, and net damages. Because of the recognition, authors have tried to develop a new rockfall protection system consisted of shock absorption parts and hexagonal net configuration. In the previous research by the authors, the performance of the newly developed rockfall protection system has been investigated through the laboratory tests and the full-scale testing. In this study, subsequently, numerical analysis program is organized to make a confirmation of the structural stability and performance. For the correct design procedure of the hexagonal net system, it is essential to understand the various mechanical behavior of the entire system. It is also important to be reproduced the systematic characteristics of the system acquired by laboratory and full-scale testing by numerical analysis in order to carry out the numerical experiment to understand various mechanical behavior of the system. As a conclusion, the hexagonal net has better performance in mechanical and physical behavior compared with that of the rectangular net. Furthermore, due to the hexagonal net shows a good performance in aspect of the load distribution, it gives a good alternative in long-term management of the rockfall protection net.

A Study on Securing a Stable GM for Each Ship Type Considering the Ship's Operating Status (선박의 운항 상태를 고려한 선종별 안정적인 GM 운용에 관한 연구)

  • Kim, Hong-Beom;Kim, Jong-Kwan;Lee, Yun-Sok
    • Journal of Navigation and Port Research
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    • v.44 no.4
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    • pp.275-282
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    • 2020
  • Recently, the occurrence of a ship capsizing was analyzed as the main cause of the lack of stability or loss because of the improper management of the center of gravity, the movement of cargo or heavy weight when excessive steering occurs or when navigating during bad weather. Thus, to prevent a ship from capsizing, it is necessary to secure stability to enable the ship's return to its upright position, even if a dangerous heel occurs. The GM is a crucial evaluation factor regarding stability, which the navigation officer uses to preserve stability. In this study, based on the stability data collected from the operating of ships for five years, The GM by ship's type according to the operating status was analyzed specifically such as a ship's length, breadth, and gross tonnage. The feature of the GM distribution according to a ship's length was confirmed, and after performing the correlation analysis between the breadth and the GM, the ratio of the GM to breadth was calculated, and the result was compared with the previous ratio. Additionally, a simple approximation formula and minimum GM for the estimation of the GM by ship type were proposed by the regression analysis of the GM using the gross tonnage (GT)/breadth (B) to reflect the trend of larger ships being built. The results of this study are expected to be used as data for the review of securing a stable GM on ships.

Monitoring of the mortalities and medications in the inland farms of olive flounder, Paralichthys olivaceus, in South Korea (양식 넙치 폐사피해 및 수산생물용 의약품 사용량 모니터링)

  • Jee, Bo Young;Shin, Ki Won;Lee, Dae Wook;Kim, Young Jae;Lee, Mu Kun
    • Journal of fish pathology
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    • v.27 no.1
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    • pp.77-83
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    • 2014
  • The monitoring was performed to survey the mortalities and medications occurred in the inland aquaculture farms of olive flounder in South Korea from May to October, 2012. Both of the indirect inquiry for entire inland farms and the sample survey for selected farms were carried out. The aquatic organism disease inspectors, who have the national licenses for the diagnosis and prevention of aquatic organism diseases and have close relationship with the farms, investigated the rates and causes of mortalities according to the standard manual. The cumulative mortalities rate by the indirect inquiry on 565 farms, was calculated to 27.18%, and the mortalities rate by infectious diseases was 22.64%. Otherwise, the mortalities rate by sample survey on 60 farms was 25.50%, 19.33% of them were caused by infectious diseases. The high mortality rates were recorded by scuticociliatosis, non-infectious loss, streptococcosis, VHS, artificial eliminations, vibriosis and gliding bacterial disease. Streptococcosis and non-infectious mortality caused to serious loss in productivity and economy of the farms, because of their outbreaks in the flounder groups over 600 g. The monitoring of medications in the selected farms revealed that formalin for the treatment of external parasites, such as scuticociliates, was the most commonly used drugs in the farms. As the antibiotic medications, amoxicillin and florfenicol for streptococcosis, and oxytetracycline and neomycin expecting wide antibacterial spectrum, were frequently prescribed.

Phosphorus and Nitrogen Rate Effects to a Newly Seeded Kentucky Bluegrass (질소와 인산의 시비량이 새로 조성된 Kentucky Bluegrass에 성장에 미치는 영향)

  • Lee, Sang-Kook
    • Asian Journal of Turfgrass Science
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    • v.25 no.2
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    • pp.217-222
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    • 2011
  • Professional turfgrass applicators have reduced or eliminated phosphorus from their fertilization programs based on the assumption that soil phosphorus levels are supplying adequate amounts of phosphorus to the turfgrass. The previous researchers found that there were no P effects for turfgrass growth especially for mature turf. No effects may result from high P level in heavy thatch layer. The research was conducted for one year to investigate the effects of phosphorus fertilization programs on turfgrass performance, and monitor soil and plant tissue nutrient levels to determine the impact of the programs on a newly seeded Kentucky bluegrass. The nitrogen treatments were 20, 30 and $40g\;m^{-2}\;yr^{-1}$. The low, medium, and high nitrogen treatments were applied over 2, 4 and 6 applications, respectively. Nitrogen was applied using a formulation containing 30% of slow and 70% of fast release nitrogen sources that are representative of typical home lawn fertilizers. The phosphorus treatments were 0, 10 and $20g\;m^{-2}\;yr^{-1}$. Phosphorus was applied according to the application schedule for the nitrogen treatments. Kentucky bluegrass was seeded in May, 2010. The thickness of thatch layer was less than 1 cm and the first treatment was applied to Kentucky bluegrass in April, 2011. The low N rate treatment had acceptable color and quality ratings without high clipping yields. The high N rate treatment consistently had the highest color and quality ratings but also had very high clipping yields in comparison to the low and medium N rate treatments. Although there are significant differences in tissue P, Overall, there was no effect of phosphorus on color, quality, or clipping weights.

A Study on the Quantitative Measurement of Oil Carry-over in Natural Gas Vehicle fueling Station Using A Gravimetric Method (무게측정법을 이용한 천연가스 자동차 충전소 오일전이 정량 분석에 대한 연구)

  • Hwang, Sung-Soo;Oh, Jun-Seok;Kim, Ki-Dong;Oh, Young-Sam;Choi, Kyung-Sik;Kim, Hack-Eun
    • Journal of the Korean Institute of Gas
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    • v.19 no.1
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    • pp.12-17
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    • 2015
  • The core of the CNG fueling station is the compressor and most of CNG compressors in Korea require lubrication. Lubrication oil of CNG compressor that can be transferred into the pressure regulators and the engines of fueling system can cause a negative effect on NGV(Nature Gas Vehicle) performance during refueling due to oil Carry-over. In order to avoid the problem, it is necessary to enhance the quality of the compressed natural gas by measuring quantitatively the amount of the transferred oil. In this research, a sampling device and sampling tube were developed, which can be used with a gravimetric method of detection to measure CNG oil Carry-over. In addition, CNG samples were taken at 6 pre-selected CNG fueling stations and analysed for their trace oil Carry-over. The measured total oil Carry-over ranged from 2.569 to 6.509 ppm. This test measurements were compared with those of previous studies to verify the results.

Analysis of the Drying Characteristic of Wastewater Sludge by Microwave to Make Energy Resources (하수슬러지의 에너지 자원화를 위한 마이크로파 건조특성 분석)

  • Lee, Seongmin;Lee, Yoonsik
    • Journal of the Korean GEO-environmental Society
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    • v.10 no.7
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    • pp.125-133
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    • 2009
  • Wastewater sludge had normally filled up in land before revising the law of waste material management in 2003, which does not permit landfill of organic sludge in Korea. After the law, most sludge has been littered in the ocean up to now. However, due to the London Convention 96 Protocol, littering sludge in the ocean will also be prohibited after 2011. This Protocol makes countries find out new methods to treat wastewater sludge. There is no exception in Korea too. Many researchers have urgently try to find out better ways to treat sludge. One of ways is to make sludge recycle energy and the success of it depends on drying method. Specifically, it really depends how to make sludge dry ecologic friendly and economic efficiently. Therefore, wastewater sludge produced in Youngdong was analyzed to make it energy resources in this study. The sludge was tested to analyze the drying and chemical characteristics of it by irradiating microwave. In the result, it is sure that the sludge has little heavy metals as like as others in country side. High calories, 3370 Kcal, shows that it has good potential to be recycle energy. Moreover, weight deduction of the sludge vs. time shows long S-curve and has same deduction ratio. Specifically, S-curve can be divided by three sections based on the curvature points. There are steady state reduction ratio of weight and approximately 80% of weight duction in the second section. This results can be used to estimate the amount of sludge reduction in the full-scale microwave dryer. Drying capacity of microwave shows approximately 1.0 kg/kw/hr. It makes sure that sludge recycle energy has the potential of economic efficiency too.

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Measurement and Analysis of Low Flow in the Cheonggecheon Watershed (청계천 유역 갈수량 측정 및 분석)

  • Noh, Seong Jin;Kim, Hyeon Jun;Jang, Cheol Hee;Kim, Dong Pil;Hong, Il Pyo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2004.05b
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    • pp.1067-1071
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    • 2004
  • 도시 유역의 물순환 특성을 종합적으로 이해하기 위해서는 갈수량 자료의 구축이 필수적이다. 하지만 지금까지의 인구는 주로 치수분야에 한정되어 대부분의 자료 또한 홍수기에 대해서만 자료가 구축되어 있으며 상대적으로 갈수기에 내한 자료와 관련 연구는 부족한 편이다. 본 연구에서는 청계천 유역의 기존 수문자료를 이용하여 유역의 유출 특성을 분석하고 갈수량을 측정하여 청계천 유역의 물순환 특성을 파악하기 위한 기초자료를 구축하였다. 청계천은 서울의 서북쪽에 위치한 인왕산과 북한산의 남쪽 기슭, 남산의 북쪽 기슭에서 시작하여 서에서 동으로 종로, 세운상가, 동대문 등 서울의 도심부를 흐르는 유로연장 13.75 km, 유역 면적 $50.96 km^2$의 도시하천으로 중량천의 제1지류인 지방2급 하천이며, 정릉친, 성북천을 제1지류, 월곡천을 제2지류로 포함한다. 청계천은 도시화로 인해 1950년대부터 1970년대까지 점차 복개되었다가 2003년 7월부터 5.9 km의 본류구간에 대한 복원공사가 진행 중이다. 청계천은 홍수기 이후 유량이 급격히 줄어 11월 이후에는 다음 홍수기까지 강바닥이 완전히 들어나는 일종의 간헐천으로 홍수기를 제외한 시기의 자료는 전무한 실정이다. 본 연구에서는 유역내 8개의 모니터링 지점을 선정하여 2003년 9월 이후, 월 2회 이상 갈수량 자료를 현장 측정${\cdot}$분석하였다. 청계천 유역은 복원공사 완공 후에는 유역의 물순환 특성이 대폭 바뀔 것이 예상되는 지역으로 본 연구에서 구축된 갈수량 자료는 청계천 유역의 물순환계 변화를 분석하고 건전한 물순환 체계의 유지${\cdot}$관리를 위한 기본 자료가 될 것으로 판단된다., 바늘꽃과, 속새과, 십자화과, 장미과, 사초과, 삼과, 현삼과, 닭의장풀과가 각 1종씩 조사되었으며, 조사지점(II)인 1km지점에서는 15과 26종으로, 벼과가 4종, 마디풀과, 국화과가 3종, 버드나무과, 십자화과, 콩과가 2종씩, 바늘꽃과, 속새과, 자라풀과, 장미과, 사초과, 백합과, 현삼과, 골풀과, 닭의장풀과가 각 1종씩으로, 조사지점( I )보다 좀 더 많은 종이 분포하는 것으로 조사되었다. 또한 어류는 조사지점( I )에서 3회에 걸쳐 총 396개체가 채집되어 3목 8과 21종이었다. 이 중 한국 고유종은 11종이었고, 외래 어종은 검정우럭과 2종이 조사되었으며, Zacco platypus(피라미), Zacco temmincki(갈겨니), Acheilongnathus koreanus(칼납자루), Odontobutis platycephala(동사리), Coreoleuciscus splendidus(쉬리) 순으로 분포하고 있었고, Acheilognathus signifer(묵납자루)는 댐 건설 전에는 많이 분포하였으나 현장조사에서 서식을 확인 할 수 언어 개체수의 큰 감소내지 멸종된 것으로 추정되었다.에서 동시에 시행하였다. 수술 후 1년 내 시행한 심초음파에서 모든 환아에서 단지 경등도 이하의 승모판 폐쇄 부전 소견을 보였다. 수술 후 조기 사망은 없었으며, 합병증으로는 유미흉이 한 명에서 있었다. 술 후 10개월째 허혈성 확장성 심근증이 호전되지 않아 Dor 술식을 시행한 후 사망한 예를 제외한 나머지 6명은 특이 증상 없이 정상 생활 중이다 결론: 좌관상동맥 페동맥이상 기시증은 드물기는 하나, 영유아기에 심근경색 및 허혈성 심근증 또는 선천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다

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Sediments and Design Considerations in the Forebay of Stormwater Wetland (강우유출수 처리목적 인공습지 침강지의 퇴적물 특성 및 설계 적정성에 관한연구)

  • Park, Kisoo;Cheng, Jing;Kim, Youngchul
    • Journal of Wetlands Research
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    • v.14 no.2
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    • pp.223-235
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    • 2012
  • In this paper, field study results about accumulation of sediments and its property in the forebay of wetland aiming at stormwater from rural area wherein intensive cow feeding lots are operated are provided. In addition, some design aspects are discussed. Amount of sediment generation in the longitudinal direction of forebay was found to be affected by hydrological factors such as rainfall depth and intensity. Nutrient contents in the sediments of this wetland were 10 times higher than those in stormwater wetland in rural area without animal-feeding lot. Total-Pb and As contents show similar level to values from the soils of surrounding watershed, but Total-Cu content was higher due to the animal feeding lots. Yearly amount of sediment generation, its depth and volume were estimated to 13tons, 23cm, and $65m^3$. Based on these results and recommended guideline by Korean Ministry of Environment, dredging frequency was found to be about 2.7years. The shape of forebay has to be carefully designed to deal with a great change in flow rate. According to the results of sediment depth analysis, instead of the present rectangular, wedge-shape forebay is more desirable in handling scouring caused by high flows.

Changes in Palatability of Cooked Rice by Blending High Quality Rice or Glutinous Rice to Low Quality Rice and by Blending Rice of Different Varieties (불량식미쌀에 대한 우량식미쌀 및 찹쌀의 혼합과 쌀의 품종간 혼합이 밥맛에 미치는 영향)

  • Yong-Woong Kwon;Je-Cheon Chae;Jeon-Woo Bang
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.36 no.4
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    • pp.351-359
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    • 1991
  • Demand for the rice of better eating quality is ever increasing in recent years. However. the rice is presently handled by the government and merchants as mixture of the rice of different varieties from the purchase of the rough rice to storing and milling. It is well known that the eating quality of rice varies significantly by variety. The present study aimed at evaluation of the effect of blending different rices on the change in palatability of low and high eating quality rices. The eating quality of a low quality japonica rice was improved significantly on sensory panel test by blending it with the Dongjin rice. one of the highest eating quality. only when the Dongjin was blended to 80 percent by weight. and also it was same for blending an ordinary quality rice of mixed varieties which has been stored by a governmental storehouse with a top class rice on free market. The eating quality of aged Tongil type rice. produce of 1987 and 1989 and a mixture of varieties, was improved significantly by blending it with a high quality glutinous rice on market to 20 per cent by weight. But Samgang rice. a high eating quality Tongil type variety. and an ordinary quality rice of Japonica varieties were not significantly improved by blending them with the glutinous rice by 20 per cent. Blending rices of the variety Nagdong. ordinary quality among varieties and low quality among Japonicas, Chucheong, a high quality rice among Japonicas. and Dongjin. one of the best eating quality rice among Japonicas, each other in different ratios did not affect significantly the sensory scores.

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