• 산업기술연구
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• 제21권B호
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• pp.341-348
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• 2001

The effect of initial ${\alpha}^{\prime}$ in STS 304 Stainless Steel on fatigue resistance, and fatigue crack propagation behavior was studied with using C-T specimens. Higher ${\Delta}K_{th}$ was observed in the specimens with the content of 0% initial ${\alpha}^{\prime}$ than in the contents of 2% and 33% initial ${\alpha}^{\prime}$. The difference of da/dN at the same level of ${\Delta}K$ was distinctive in low and intermediate level of ${\Delta}K$ however became less different as the level of ${\Delta}K$ increased. It is because the formation of strain induced martensite occurred readily in lower ${\alpha}^{\prime}$ at the vicinity of the fatigue crack tip, which causes compressive residual stresses resulting in the enhancement of crack closure. In general fatigue cracks propagated transgranular mode and many segments of ridges were observed on the fracture surfaces. At the higher contents of initial ${\alpha}^{\prime}$ appeared the smaller size of ridge segments. Slips in austenite were blocked more frequently by the martensite colonies formed in austenite.

• Journal of Welding and Joining
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• 제31권4호
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• pp.54-61
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• 2013

This paper reports mild steel(SPHC) and stainless steel(STS304) sheets commonly used for railroad cars or commercial vehicles such as in the automobile and shipbuilding industries. The sheets are used in these applications, which are mainly fabricated using the shielded metal arc welding(SMAW) of dissimilar materials. It also reports an interesting application of Laser Induced Breakdown Spectroscopy(LIBS) in order to determine the elemental composition diffusion of SPHC and STS304. Arc blow produced by magnetic force during the electric arc welding prevents the formation from a sound weldment. In particular, the mechanical properties of the joint are influenced by not only by geometrical and mechanical factors but also the welding conditions for the arc welded joint. Therefore, the mechanical properties and performance are evaluated by performing a physicochemical component analysis. And they increase in accordance with content of elements and microstructure in mild steel. As results, appropriate range for magnetic fields could be achieved. Therefore, the effect of magnetic force in a butt weld of mild steel plates was investigated by comparing to the measured data.

• 대한지구과학교육학회지
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• 제9권3호
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• pp.269-275
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• 2016

본 연구는 우리나라의 과학과 교육과정 중 과학적 소양이 교육의 목표로 제시된 7차 교육과정부터 2015 개정 교육과정까지 '과학' 과목의 지구과학영역 내용 변화를 과학적 소양의 측면에서 알아보기 위해 실시되었다. 지구과학 영역을 천문, 지질, 기상, 해양 내용으로 구분하여 과학적 소양의 요소 중에서 STS적인 요소에 초점을 두고 내용을 분석하였다. 천문과 기상 내용 영역에서는 7차부터 2015 개정 교육과정까지 모든 시기에서 과학적 소양의 측면이 나타났으며, 지질 영역에서는 2007 개정 교육과정, 해양 영역에서는 7차 교육과정을 제외하고 모든 시기에서 과학적 소양의 측면이 나타났다. 천문 내용 영역에서는 과학과 기술의 유용성이 강조되었고, 지질과 기상 내용 영역에서는 일상생활에서의 과학의 이용이 강조되었다. 해양 내용영역에서는 자원부족과 환경오염 등 과학관련 사회적 이슈가 강조됨을 알 수 있었다. 이 연구는 우리나라 과학과 교육과정을 과학적 소양이라는 새로운 측면에서 살펴보려는 시도로 차후 지구과학의 다른 영역 및 물리, 화학, 생물 과목으로 확대하여 내용을 살펴볼 수 있을 것이며, 더 나아가 기존의 물리, 화학, 생물, 지구과학이라는 과목의 테두리에서 벗어나 통합된 학문의 관점에서 과학적 소양을 알아볼 것을 제안한다.

• 원예과학기술지
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• 제35권4호
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• pp.465-479
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• 2017

Chili pepper (Capsicum annuum L.) is an economically important horticultural crop in Korea; however, various diseases, including Phytophthora root rot, anthracnose, powdery mildew, Cucumber mosaic virus (CMV), Pepper mild mottle virus (PMMoV), and Pepper mottle virus (PepMoV), severely affect their productivity and quality. Therefore, pepper varieties with resistance to multiple diseases are highly desired. In this study, we developed 20 SNP type assays for three pepper populations using Fluidigm nanofluidic dynamic arrays. A total of 4,608 data points can be produced with a 192.24 dynamic array consisting of 192 samples and 24 SNP markers. The assays were converted from previously developed sequence-tagged-site (STS) markers and included markers for resistance to Phytophthora root rot (M3-2 and M3-3), anthracnose (CcR9, CA09g12180, CA09g19170, CA12g17210, and CA12g19240), powdery mildew (Ltr4.1-40344, Ltr4.2-56301, and Ltr4.2-585119), bacterial spot (Bs2), CMV (Cmr1-2), PMMoV (L4), and PepMoV (pvr1 and pvr2-123457), as well as for capsaicinoids content (qcap3.1-40134, qcap6.1-299931, qcap6.1-589160, qdhc2.1-1335057, and qdhc2.2-43829). In addition, 11 assays were validated through a comparison with the corresponding data of the STS markers. Furthermore, we successfully applied the assays to commercial $F_1$ cultivars and to our breeding lines. These 20 SNP type assays will be very useful for developing new superior pepper varieties with resistance to multiple diseases and a higher content of capsaicinoids for increased pungency.

• 대한화학회지
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• 제47권4호
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• pp.391-400
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• 2003

본 연구는 제6차 교육과정에서 강조한 탐구활동을 탐구내용, 탐구과정, 탐구상황의 3차원 분석틀을 이용하여 화학II 교과서를 분석하였다. 그 결과, 탐구활동의 탐구내용을 보면, 각 교과서마다 탐구활동이 관찰, 실험, 측정, 토의, 자료해석, 기본조작 등의 다양한 용어로 분류되어 있으며, 교과서마다 분류 기준에 다소 차이가 있었다. 각 교과서의 탐구내용에 수록된 탐구활동의 수는, 7개 교과서 모두 25개에서 35개 정도로 수록되어 있었다. 각 교과서의 탐구내용에 있는 탐구활동의 평균수는 각 단원에서 적게는 10${\%}$에서 많게는 30${\%}$로 분포되어 있었다. 또한 탐구과정 영역은 평균적으로 ''관찰 및 측정''이 가장 많았고, 그 다음으로 ''자료해석 및 일반화'', ''문제발견 및 해결방안'', ''이론모델셩성, 검증 및 수정''의 순서로 나타났다. 그리고 탐구상황 영역은 과학적 상황요소가 90.5%로 가장 많은 부분을 차지하였고, 그 외에 개인적 상황요소, 사회적 상황요소, 기술적 상황요소가 약 5%를 차지하였다. 이러한 분석으로부터 볼 때, STS(과학-기술-사회)의 상호관련성을 강조한 내용이 아직은 매우 미흡한 것으로 나타났다.

• 한국축산식품학회지
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• 제30권4호
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• pp.582-589
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• 2010

The current study was designed to assess the effects of emulsified sausage supplemented with ginseng saponin on lipid metabolism by applying a rat model. Four groups of 8 rats (5 wk old) were each allocated one of 4 treatments: basal feed (C), and basal feed with 20% sausage powder containing 0% (S0), 2% (S2) and 4% (S4) ginseng saponin. The experiment was conducted for 4 wk. The results did not differ among the treatments with different amounts of sausage (ST), but daily feed intake (p<0.01) and feed conversion (p<0.001) were significantly increased in STs compared to C. Both total serum cholesterol and triglyceride concentrations were significantly (p<0.001) reduced, by 45 and 46%, and 48 and 46%, in S2 and S4, respectively, compared to S0. In the liver, the total cholesterol level was dramatically (p<0.05) decreased according to increasing sausage powder levels. In particular, S4 showed approximately 14% reduction compared to S0 (p<0.05). Liver triglyceride content also showed a similar tendency, where S2 and S4 resulted in 7% and 31% reduction. With regard to fatty acid composition in the liver tissues, palmitic acid (16:0), oleic acid (18:1), eicosanoic acid (20:1), and eicosatrienoic acid (20:3) did not differ among the STs, whereas both linoleic acid (18:2) (p<0.01) and linolenic acid (18:3) (p<0.001) showed significant increases in S2 compared to S0. The current data demonstrated that emulsified sausages supplemented with ginseng saponin effectively reduce total cholesterol and triglyceride concentrations in the serum and liver, and increase unsaturated and essential fatty acid in the liver. These data collectively imply that the sausage improved the overall lipid profile in a rat model, and can be further generalized to the result that emulsified sausage can improve lipid metabolism depending on the products' formula.

• 한국추진공학회지
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• 제23권2호
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• pp.118-125
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• 2019

산화제 과잉 예연소기는 고온/고압/산화제 과잉의 환경이며, 이러한 환경에 금속은 급격한 산화가 발생할 수 있다. 본 연구에서는 고온/고압/산화제 과잉의 환경을 모사할 수 있는 설비를 구축하고 여러 금속 재질에 대해 내산화성 평가를 진행하였다. 그 결과, 온도가 높고 압력이 높은 조건에서 금속재질의 변색, 표면 거칠기에 변화와 금속 표면의 박리 현상이 관찰되었고 무게 변화도 확인하였다. 모든 실험 결과를 종합하였을 때 산화제 과잉 예연소기는 금속 재질에 대한 내산화 코팅이 필수적으로 요구되며, 사용 금속으로는 Cr과 Ni의 함유량이 가장 높은 XM-19를 활용하는 것이 좀 더 구조적 안정성을 확보할 수 있을 것으로 판단한다.

• Fisheries and Aquatic Sciences
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• 제20권7호
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• pp.12.1-12.7
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• 2017

Soft tunic syndrome (STS) is a protozoal disease caused by Azumiobodo hoyamushi in the edible ascidian Halocynthia roretzi. Previous studies have proven that combined formalin-hydrogen peroxide ($H_2O_2$) bath is effective in reducing STS progress and mortality. To secure target animal safety for field applications, toxicity of the treatment needs to be evaluated. Healthy ascidians were bathed for 1 week, 1 h a day at various bathing concentrations. Bathing with 5- and 10-fold optimum concentration caused 100% mortality of ascidians, whereas mortality by 0.5- to 2.0-fold solutions was not different from that of control. Of the oxidative damage parameters, MDA levels did not change after 0.5- and 1.0-fold bathing. However, free radical scavenging ability and reducing power were significantly decreased even with the lower-than-optimal 0.5-fold concentration. Glycogen content tended to increase with 1-fold bathing without statistical significance. All changes induced by the 2-fold bathing were completely or partially restored to control levels 48 h post-bathing. Free amino acid analysis revealed a concentration-dependent decline in aspartic acid and cysteine levels. In contrast, alanine and valine levels increased after the 2-fold bath treatment. These data indicate that the currently established effective disinfectant regimen against the parasitic pathogen is generally safe, and the biochemical changes observed are transient, lasting approximately 48 h at most. Low levels of formalin and $H_2O_2$ were detectable 1 h post-bathing; however, the compounds were completely undetectable after 48 h of bathing. Formalin-$H_2O_2$ bathing is effective against STS; however, reasonable care is required in the treatment to avoid unwanted toxicity. Drug residues do not present a concern for consumer safety.

• 열처리공학회지
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• 제20권2호
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• pp.84-93
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• 2007

Microstructural changes during tempering at the temperature range of $300^{\circ}C{\sim}700^{\circ}C$ for the nitrogen-permeated STS 410 and 410L martensitic stainless steels has been investigated. After nitrogen permeation at temperature between 1050 and $1150^{\circ}C$, the surface layer appeared fine $Cr_2N$ of square and rod types in the martensite matrices. Hardness of the nitrogen-permeated surface layer represented 680Hv and 625Hv, respectively, for 410 and 410L steels. It is considered that the fine homogeneously dispersive effect of precipitates by nitrogen caused the increased hardness. Due to the counter current effect of carbon from interior to surface during nitrogen diffusion from surface to interior, the 0.1%C alloyed 410 steel showed the low nitrogen content of 0.025% compared with 0.045% of 410L steel at the distance of $100{\mu}m$ from the surface. Tempering of nitrogen-alloyed 410 and 410L showed the maximum hardness at $450^{\circ}C$. This maximum hardness was considered to be the secondary hardening effect of very fine carbide and nitride. The decrease in hardness at $700^{\circ}C$ was the softening effect of the matrix due to the precipitation of many needle-shaped $Cr_2N$ for 410 steel and the precipitation of coarse nitride of $Cr_2N$ in line with the spherical precipitates with directionality for 410L steel. For 410 steel, the corrosion resistance of nitrogen permeated surface in the solution of 1 N $H_2SO_4$ were nearly unchanged, however the superior corrosion resistance was obtained for nitrogen permeated 410L steel compared to the solution annealed condition.

• Corrosion Science and Technology
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• 제4권6호
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• pp.226-230
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• 2005

Si incorporated diamond-like carbon (Si-DLC) films ranging from 0 to 2 at.% contents were deposited on STS 316L substrates for orthopedic implants by means of r.f. plasma-assisted chemical vapor deposition (r.f. PACVD) technique, using mixtures of benzene ($C_6H_6$) and silane ($SiH_4$) as the precursor gases. This study provides the reliable and quantitative data for assessment of the effect of Si incorporation on corrosion property in the simulated body fluid environment through the electrochemical test. It was found that corrosion to resistance of Si-DLC coatings with increasing Si content are improved owing to high $sp^3$ bonding.