• Title/Summary/Keyword: 개량효과 확인

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A study on the residual stress at the weld joint of 2.25Cr-1.6W heat resistant steel (보일러용 배관재 2.25Cr-1.6W계 내열강의 용접부 응력 해석)

  • Lee, Y.S.;Lee, K.W.;Lee, J.B.;Kim, Y.D.;Kong, B.W.;Ryu, S.H.;Kim, J.T.;Kim, B.S.;Jang, J.C.
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.62-62
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    • 2009
  • 석탄화력발전소의 CO2배출량 감소와 고효율, 대용량화로 인해 초초임계압(USC:Ultra Super Critical) 화력발전소의 건설이 증가하고 있다. USC 발전소는 효율향상을 위한 증기온도와 압력의 상승 때문에 보일러 고온고압부에 기존의 소재에 비해 고온강도와 내산화성의 재료물성이 향상된 신소재 적용이 불가피하다. 특히 사용된 신소재 중에서 보일러 본체를 구성하는 수냉벽관(Water wall), 과열기와, 재열기용 튜브 및 후육부인 헤더와 배관재로 기존의 2.25Cr-1Mo강을 개량한 2.25Cr-1.6W계 내열강이 적용되고 있다. 2.25Cr-1.6W강은 SMI와 MHI가 공동개발한 소재로 1995년 튜브제품이, 1999년에 단조, 파이프재, 플레이트제품이 ASME code case로 등재되었고, 2009년 ASME code case 2199-4로 개정되어 사용 중이다. 이 소재는 2.25Cr-1Mo강에 고온강도 개선을 위해 석출강화효과가 있는 V과 Nb을 첨가하였고, 탄화물의 열적안정성과 고용강화효과 증대를 위해 W을 첨가하였다. 그리고 제작성과 용접성 및 재료의 인성 향상을 위해 B첨가와 C함량을 낮추었다. 합금성분의 첨가와 조정에 의해 고온강도는 개선되었지만, 보일러 설치 및 보수를 위한 용접과정에서 용접금속과 CGHAZ(Coarse Grain HAZ)에서 용접균열이 발생하였다. 대부분의 용접균열은 용접결함이나 고온 혹은 저온균열이 아닌 2.25Cr-1.6W계강의 강도 개선을 위해 첨가한 V과 Nb이 용접후열처리 도중 입내에 MX형태의 미세석출로 입내를 강화시킴으로서 발생한 재열균열 민감성 증대에 기인된 것으로 판단된다. 이에 본 연구에서 용접 및 후열처리 과정에서 용접금속과 HAZ에서 발생하는 용접금속의 응력분포를 전산해석을 통해 확인하고 실제 후육파이프 용접부에서 잔류응력을 측정해 비교하였다. 용접부 응력분포는 SYSWELD 프로그램을 사용해 해석을 수행하였고, 발전소 실배관재의 용접부 응력측정은 수평부 측정이 용이하도록 지그를 부착한 Potable 잔류응력측정기를 사용해 Hole Drilling Method(HDM)를 적용하여 잔류응력을 측정하였다. 해석 결과 CGHAZ부위의 잔류응력이 용접금속과 기타 부위에 비해 높은 응력분포를 나타냈으며, 이는 CGHAZ와 용접용융선 부근에서 균열이 발생하는 실제값과 일치하는 결과를 보였다. 실제 배관재 용접부에서 측정한 잔류응력값은 항복응력의 약 50% 이하 응력값을 나타냈다. 배관 구조에 기인한 시스템응력의 영향을 제거하기 위해 배관재 용접부를 중심으로 양끝단을 절단 후 용접부에서 측정한 응력은 항복응력 대비 25%수준의 낮은값을 보였다. 그러나 배관재가 장기간 고온환경에 노출되었고 용접금속 내부의 균열이 발생한 상태에서 측정하였기 때문에 용접잔류응력은 상당부분 해소되어 상대적으로 낮은 응력값이 얻어진 것으로 판단된다.

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A Study on the Stormwater Drainage Method of Overflow Type for the Prevention of Urban Flood due to Abnormal Precipitation (이상강우 발생시 도시침수 방지를 위한 월류형 우수배수방법 연구)

  • Seo, Se Deok;Park, Hyung Keun;Kim, Tae Hyun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.5
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    • pp.569-577
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    • 2019
  • Urban flooding has been a frequent phenomenon in recent years caused by the increase in maximum stormwater runoff arising from abnormal rainfall due to global warming, urban development, and development of lowlands according to population inflows. In order to respond positively against abnormal precipition in the city, it is necessary to check the GWI (Green Water Infra) effect and effectively utilize the existing stormwater detention tanks and treat stormwater to prevent local flooding. In this study, Overflow Type stormwater drainage methods are evaluated as a method of preventing urban flooding in abnormal precipitation using the Dynamic Wave Analysis SWMM (Storm Water Management Model) provided by the United States Environmental Protection Agency. Comparing and analyzing the Upward Watergate Type and Overflow Type, it was analyzed that the Overflow Type reduces the maximum flood discharge by 61 % and the total flood volume by 56 % in the rainfall of Typhoon Kong-rey. The application of the Overflow Type and the natural-pneumatic drainage method to the rainfall of Typhoon Soulik resulted in a 20 % reduction in maximum flood runoff and a 67 % reduction in total flood quantity. Therefore, as a solution to the abnormal rain fall, it is possible to improve the existing stormwater detection tank and install additional facilities. It is expected to be economically possible to strom drainage under limited conditions.

Determination of Antifungal Activity on Pepper Anthracnose and Plant Growth Promoting Activity of Pleurospermum camtschaticum Root Extract (누리대 뿌리 추출물의 고추 탄저병에 대한 항균 및 생장 촉진 활성 검정)

  • Inkyu Lee;Young Sun Baek;Youn Su Lee
    • Research in Plant Disease
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    • v.29 no.3
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    • pp.268-275
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    • 2023
  • This study was conducted to confirm the utilization of Pleurospermum camtschaticum root extract as an organic agricultural material. Antioxidant activity of P. camtschaticum root extract, closely related to antibacterial activity, increased in a dose-dependent manner. In mycelial growth inhibitory activity, 100% P. camtschaticum root extract supressed over 70% for Colletotrichum coccodes and over 68% for Colletotrichum dematium. In the pepper fruit anthracnose development test, the size of the lesion decreased in a dose-dependent manner, which showed the same tendency as the previous results in inhibitory activity on mycelial growth. In the pepper seed germination and red pepper growth promotion test of P. camtschaticum root extract, oposite results was confirmed. The lower the concentration, the more the seed germination and growth promotion effects were shown. The phenol content of pepper leaves was also measured after pepper growth promotion test have been completed. The phenol content related to antibacterial activity increased in all treated groups compared to the untreated group. Therefore, the results of this study showed the possibility of development as an organic material.

Research of Statistical Model for Genetic Evaluation of Hanwoo Carcass Traits (한우 도체형질의 유전능력평가를 위한 통계모형 탐색)

  • Koo, Yang-Mo;Kim, Si-Dong;Kim, Jung-Il;Song, Chi-Eun;Lee, Ki-Hwan;Jeoung, Yeoung-Ho;Lee, Jae-Youn;Jang, Hyun-Gi;Park, Byoung-Ho;Choi, Te-Jong;Cho, Kwang-Hyun;Lee, Seung-Soo;Lee, Jung-Gyu;Kim, Hyo-Sun
    • Journal of Animal Science and Technology
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    • v.53 no.4
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    • pp.283-288
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    • 2011
  • This study was conducted to study the environment effects on live weight, carcass weight, dressing percentage, eye muscle area, backfat thickness, and marbling score, which are the carcass traits of Hanwoo, based on the estimates and all the possible regression for the selection of variable and significance test for 231,382 heads that underwent the carcass measurements. The average and standard deviation for the live weight, carcass weight, dressing percentage, eye muscle area, backfat thickness, and marbling score were 654.79${\pm}$91.61 kg, 362.30${\pm}$67.15 kg, 59.52${\pm}$0.03%, 81.79${\pm}$12.21 $cm^2$, 11.39${\pm}$5.40 mm, 4.38${\pm}$2.29, respectively. The live weight, carcass weight, dressing percentage, eye muscle area, backfat thickness, and marbling score for cow were 532.79${\pm}$78.38 kg, 313.40${\pm}$44.90 kg, 56.50${\pm}$0.03%, 75.24${\pm}$10.69 $cm^2$, 11.82${\pm}$5.10 mm, 4.30${\pm}$2.06, respectively, while for bull were 619.74${\pm}$93.27 kg, 376.89${\pm}$48.62 kg, 58.61${\pm}$0.02%, 85.61${\pm}$10.46 $cm^2$, 5.64${\pm}$2.71 mm, 1.41${\pm}$0.83, respectively, and for steer were 681.78${\pm}$70.72 kg, 415.23${\pm}$49.43 kg, 60.19${\pm}$0.02%, 88.29${\pm}$10.27 $cm^2$, 12.71${\pm}$5.23 mm, 5.42${\pm}$1.99, respectively. In the environmental variables selection based on the variables selection method, the examination by carcass traits suggested that the most appropriate model could be determined when five variables were selected for the live weight, carcass weight, dressing percentage, eye muscle area, and four variables for backfat thickness, and marbling score. When they were considered at a time altogether based on multiple traits, it was deemed to be desirable to insert all five variables into the variables for analysis. In addition, high significance was found by carcass traits.

The identification of non-synonymous SNP in the Enoyl-CoA delta isomerase 2 (ECI2) gene and its Association with Meat Quality Traits in Berkshire pigs (버크셔 돼지 육질 형질과 Enoyl-CoA delta isomerase 2 (ECI2) 유전자 nsSNP의 연관성 분석)

  • Hwang, Jung Hye;An, Sang Mi;Park, Da Hye;Kang, Deok Gyeong;Kim, Tae Wan;Park, Hwa Chun;Ha, Jeongim;Kim, Chul Wook
    • Journal of the Korean Society of International Agriculture
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    • v.30 no.4
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    • pp.277-284
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    • 2018
  • Meat quality has always been one of the most important factors that controls the choice of pork consumers and is of great interest in the pig industry. In this study, we identified a single nucleotide polymorphism (SNP) in the enoyl-CoA delta isomerase 2 (ECI2) gene in Berkshire pigs (n = 430) by analyzed the association between the SNP and meat quality traits. The non-synonymous SNP in the ECI2 gene is located at c.608 C > G and resulted in an amino acid change from threonine to serine. Significant associations between the SNP and meat quality traits, such as redness (CIE a), and the $pH_{24hr}$, were revealed in both the dominant and co-dominant models, whereas carcass weight, drip loss, and fat content and moisture content were significantly associated only with the dominant model. In barrow, the SNP was significantly associated with CIE a, drip loss, and $pH_{24hr}$, whereas in gilt, only a significant relationship with moisture content was observed. GG genotype pigs had a higher $pH_{24hr}$ and lower drip loss. Because $pH_{24hr}$ and drip loss are considered the most important meat quality traits, GG genotype pork is high-quality meat compared to that from other genotypes. In conclusion, the SNP in the ECI2 gene is significantly associated with several meat quality traits. These traits and could be as genetic markers in molecular breeding programs for improving meat quality.

An experimental study on the improving reliability of grouting by using p-q-t chart analyzing technique (P-q-t chart 분석기법을 이용한 그라무팅 신뢰성 향상 방안에 관한 실험적 연구)

  • Chon, Byung-Sik;Choi, Dong-Chan;Kim, Jin-Chun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.10 no.4
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    • pp.383-395
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    • 2008
  • The grouting is one of the improved techniques which is aim to decrease the permeability and to strengthen the soft ground. But The grouting method has many problems about a suitability of grouting procedure and an effectiveness of grouting after grouting work because of a technical characteristic operated inside the soil. The grouting $p{\sim}q{\sim}t$ chart of a typical index about grouting rate and time alteration of grouting pressure is one method to estimate the suitability of grouting factor with monitoring during grouting procedure. This study is automatic grouting system (AGS) which can control the testing and grouting procedures. It can make the detailed $p{\sim}q{\sim}t$ chart and analyze the grouting characters of the ground by comparing the detailed pattern of $p{\sim}q{\sim}t$ chart with standard pattern. If using the $p{\sim}q{\sim}t$ chart derived from AGS in the grouting work, it is an objective standard estimating the suitability of grouting factor with grouting materials, grouting method, grouting rate and grouting pressure, as results it expects successfully to improve reliability of the grouting work.

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Genetic Mapping of QTLs that Control Grain Characteristics in Rice (Oryza sativa L.) (벼의 낱알 특성에 관여하는 양적형질유전자좌 분석)

  • Wacera, Home Regina;Safitri, Fika Ayu;Lee, Hyun-Suk;Yun, Byung-Wook;Kim, Kyung-Min
    • Journal of Life Science
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    • v.25 no.8
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    • pp.925-931
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    • 2015
  • We performed a molecular marker-based analysis of quantitative trait loci (QTLs) for traits that determine the quality of the appearance of grains, using 120 doubled-haploid (DH) lines developed by another culture from the F1 cross between ‘Cheongcheong’ (Oryza sativa L. ssp. Indica) and ‘Nagdong’ (Oryza sativa L. ssp. Japonica). The traits studied included length, width, and thickness of the grains, as well as length-to-width ratio and 1,000-grain weight. The objective of this study was to determine the genetic control of these traits in order to formulate a strategy for improving the appearance of this hybrid. Within the DH population, five traits exhibited wide variation, with mean values occurring within the range of the two parents. Three QTLs were identified for grain length on chromosomes 2, 5, and 7. Three QTLs were mapped for grain width on chromosome 2: qGW2-1, qGW2-2, and qGW2-3. Six chromosomes were identified for the grain length-to-width ratio; four of these were on chromosome 2, whereas the other two were on chromosomes 7 and 12. One QTL influencing 1,000-grain weight was identified and located on chromosome 8. The results presented in the present study should facilitate rice-breeding, especially for improved hybrid-rice quality.

Centrifuge Model Test on the Bearing Capacity and Failure Mechanism of Composit Ground Improved with Slag Compaction Piles (슬래그 다짐말뚝으로 개량된 복합지반의 지지력 및 파괴메카니즘에 관한 원심모형실험)

  • Yoo Nam-Jae;Park Byung-Soo;Jeong Gil-Soo;Koh Kyung-Hwan;Kim Ji-Sung
    • Journal of the Korean Geotechnical Society
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    • v.21 no.1
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    • pp.59-67
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    • 2005
  • This paper presents experimental and numerical research results of centrifuge model tests performed to investigate the geotechnical engineering behavior of slag compaction pile as a substitute of sand compaction pile. For centrifuge model tests, bearing capacity of composit soil improved with slag compaction piles, stress concentrations in-between pile and soft clay, settlement characteristics, and failure modes were investigated with slags differing in their relative density. A slag was found to be a good substitute for a sand since the slag compaction pile model showed a greater yield stress intensity up to $30\%$ than the sand compaction pile model under the identical testing conditions. Stress concentration ratio tended to increase with the relative density of slag pile and the clear shear lines in the piles were observed at the depth of $2D{\sim}2.5D$ (D=dia. of model pile) from the top of the piles after loading tests. Numerical analysis with a software of CRISP, implemented with the modified Cam-clay model, was carried out to simulate the results of centrifuge model test. Test results about characteristics of load-settlement curves and stress concentration ratio are in relatively good agreements with numerical estimations.

Development of Sumulation Model for Breeding Schemes of Hanwoo(Korean Cattle) (한우의 개량 체계 모의실험을 위한 모형 개발)

  • Ju, J.C.;Kim, N.S.
    • Journal of Animal Science and Technology
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    • v.44 no.5
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    • pp.507-518
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    • 2002
  • A multiple-trait stochastic computer simulation model was constructed to predict the breeding schemes and selection methods on Hanwoo(Korean cattle). The model could be used four kinds of selection criteria (random, phenotype and true or estimated breeding values). At the test run in various population size for 20 years, all estimated parameters of the each simulated populations were resulted similar to input parameters. The deviations between input and output values of parameter in the large population were smaller than in the small population. The simulated results obtained from ten small populations consisted with one sire and ten dams in each population for 500 years were as follows; Inbreeding coefficients of population were similar to theoretical estimating function. Mean values of each traits selected were randomly drifted by generation, but they were converged into a value when inbreeding coefficients came close to one. Additive genetic variances within each population were reduced by generation, and they were converged into zero when inbreeding coefficients came close to one. These results indicated that the simulated populations hold to statistical properties of input parameters.

Evaluation of Flexural Strength of Wide Sleepers with Reinforcing Bars for Quick-Hardened Concrete Track (보강철근이 적용된 급속경화궤도용 광폭침목의 보유 휨 내력 평가)

  • Bae, Young-Hoon;Lee, Il-Wha
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.2
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    • pp.702-709
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    • 2018
  • A quick-hardened concrete track was developed to improve the aged ballasted track to a concrete track, and applied to earthworks and tunnels of main and urban railways. Rebars for reinforcement are not generally applied to prestressed concrete sleepers. On the other hand, many cracked sleepers have been observed in railroad sites. A wide sleeper, which is one of the main components of quick-hardened concrete track, should be structurally safe and crack-resistant in a ballasted and concrete track to avoid this problem. In particular, a wide sleeper manufactured by a post-tension method must have reinforcing bars applied to the rail-seat section. In this paper, static tests, dynamic tests, and fatigue tests were carried out to compare the flexural strength and crack resistance performance of a wide sleeper with and without reinforcing bars for a quick-hardened concrete track. As a result of the test, if some reinforcing bars are applied appropriately to the rail-seat section of a wide sleeper, it will be possible to prevent the occurrence of cracks, delay the expansion of the crack width, and the flexural fracture.