• 대한금속재료학회지
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• 제48권8호
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• pp.741-748
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• 2010

We studied the corrosion and oxidation properties of Fe-18Cr-0.4Nb-(0.1~0.6)Ti-(1~3)Si-(0.5~2)Mo stainless steel. The resistance to general and pitting corrosion was evaluated and the results were analyzed by Response Surface Methodology (RSM) as a function of alloy composition. The effects of alloy composition and heat treatment on the oxidation resistance were also examined. Mo increased both general corrosion resistance and pitting corrosion resistance. Si improved the resistance of the alloys to pitting corrosion. Si was also beneficial for general corrosion resistance of the alloys containing Mo at more than 1 wt.%. However, Mo was detrimental when its content was lower. Effects of Ti on general corrosion properties appeared to be weak and a high concentration of Ti appeared to deteriorate pitting resistance. The thickness of the oxidation scale increased and adhesion of the scale worsened as the temperature increased from $800^{\circ}C$ to $900^{\circ}C$. Weight gain of the alloys due to oxidation at $900^{\circ}C$ clearly showed that the resistance to oxidation is improved by annealing at $860^{\circ}C$ and an increase of Si content.

• 전기화학회지
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• 제3권4호
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• pp.211-218
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• 2000

마멸전극기법과 교류 임피던스법으로 스테인리스강의 합금원소, Cr, Mo, N가 합금의 재부동태 특성에 미치는 영향을 조사하였다. Fe-Cr, Fe-Cr-Mo, 304, 304LN, 316, 316LN등의 스테인리스강을 시편으로 사용하였으며 각 합금의 부동태 피막의 전기화학적 특성은 in-situ시험 기법인 d.c와 a.c전기화학적 기법을 각각 이용하였다 스테인리스강이 국부부식에 대하여 강한 저항성을 가지려면 부식 환경에서도 치밀한 부동태 피막을 유지해야 하고 피막의 파괴가 발생하더라도 재부동태 속도가 빨라야 하기 때문에 합금원소가 시간에 따른 재부동태 전류밀도와 재부동태 속도에 미치는 영향을 마멸 전극 시험법과 교류 임피던스 시험법으로 알아보았다. 부동태 피막의 안정성, 재부동태 속도 그리고 합금원소 사이의 관계를 규명하기 위하여 실험결과를 분석하였다.

• Korean Journal of Acupuncture
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• 제30권4호
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• pp.272-280
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• 2013

Objectives : The aim of this study was to observe effects of manual acupuncture(MA), electro-acupuncture(EA) and moxibustion (MO) on the rat with loperamide-induced constipation. Methods : This study measured small intestinal motility and number of fecal pellets in rats with loperamide induced constipation. MA and EA(intensity, 5 times muscle twitch threshold) was applied for 30 minutes and MO was treated on 5 times moxa cautery to the groups divided with age and sex. Results : The small intestinal motility was decreased by ST36 EA and ST37 EA in 5 weeks male group and ST37 EA in 7 weeks male and female groups, and ST36 MO in 7 weeks female group, but it was increased by ST39 EA in 7 weeks male group and ST37 MO and ST39 MO in 7 weeks male group. The number of fecal pellets was decreased by MA, EA, MO of ST36 in all group except 5, 7 weeks male groups only, and MA, EA of ST37 in 5, 7 weeks male group and ST37 MO in 7 weeks female group, and ST39 EA in 5 weeks male group and 7 weeks female group and ST39 MO in 7 weeks female group, but increased by ST37 EA in 5 weeks female group and ST39 EA in 7 weeks male group. Conclusions : Although these differences do not have a established tendency, it suggests that acupuncture and moxibustion are experimentally dependent upon the sex and age on intestinal motility in rats.

• Nutrition Research and Practice
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• 제13권6호
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• pp.529-534
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• 2019

BACKGROUND/OBJECTIVES: The leaves of Moringa oleifera (MO) and Moringa stenopetala (MS) commonly grown in Ethiopia possess potential nutritional and medicinal value. The aim of this study was to evaluate the nutritional and functional characteristics of the dried leaf powder from two Moringa species to develop sustainable nutritional supplements for Ethiopians from locally grown plant sources. MATERIALS/METHODS: Freshly harvested and air-dried MO and MS leaves were authenticated and the nutritional contents, such as protein, ash, lipids, and selected vitamins and minerals, were analyzed using standard analytical procedures. Amino acid compositions were also determined by an amino acid analyzer. Nine-week-old mice were randomly divided into four groups to investigate the anti-obesity effects of Moringa. The first group was fed a basal diet, the second group a high-fat diet, and the others were fed a high-fat diet containing 0.1% Moringa leaf powder from each species. After seven weeks, serum indices related to lipid profiles from each mouse were analyzed. RESULTS: The present study revealed high protein (28-29%) and ash (7-11%) contents. Glutamic acid, aspartic acid, proline, and leucine were the most abundantly found amino acids in both species. The predominant minerals in the leaf powder were calcium (826-1,530 mg/100 g), potassium (794-904 mg/100 g), and magnesium (286-431 mg/100 g). Pyridoxine (475.06 mg/100 g) and vitamin E (34.2 mg/100 g) were found only in MS. Niacin was found only in MO at 32.21 mg/100 g, whereas ascorbic acid was found in both species (3.89 and 6.19 mg/100 g dry weight for MO and MS, respectively). The results of the animal study showed that mice on a high-fat diet containing 0.1% MO leaf powder alleviated the elevation of cholesterol, triglycerides, and low-density lipoprotein cholesterol induced by the high fat diet. MO was more effective than MS in preventing hypercholesterolemia and fat deposition. CONCLUSION: The findings in this work confirmed that Moringa leaves of both MO and MS possessed high nutritional value but MO was better at preventing the harmful effects of the high-fat diet than MS.

• 한국주조공학회지
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• 제16권2호
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• pp.141-148
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• 1996

In high chromium cast iron, the control of matrix microstructure as well as carbide structure is important to the performance as a wear resistant material. In this study, 3.0% C-24.0% Cr white cast irons with various molybdenum contents(residual, 1.0%, 3.0% and 5.0%) were solidified conventionally and unidirectionally for studying their effects on the microstructure and hardness. In the conventional casting, two sets of castings were poured from each melt. One set of the castings consisted of cylindrical bars of 10 and 20mm by 155mm long. The second set of the castings was a cylindrical bar of 30mm by 200mm long. On the other hand, a pep-set mold set on the Cu plate was employed to make the solidification unidirectionally. X-ray diffraction method was used to observe retained austenite and carbides in the high chromium cast iron. The morphology of eutectic $M_7C_3$ carbides changed from needle-like type to nodular type with the increase of Mo content. And, the presence of $M_2C$ carbides was identified in the sample where Mo was added over 3.0 %. Primary and eutectic carbides appeared as rod type and corngrain type, respectively in the unidirectionally solidified samples which were cut to parallel to the solidification direction. In the EDX analysis, Cr concentration was higher in the primary and eutectic $M_7C_3$ carbides, Mo in the $M_2C$ carbides, and Fe in the matrix.

• 한국초지조사료학회지
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• 제23권4호
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• pp.237-246
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• 2003

Orchardgrass 및 white clover의 단파 및 혼파재배조건에서 미량요소 Fe, Mn, Cu, Zn, Mo 및 B의 조합시비가 목초의 생육, 개화, 수량, 양분 함량 및 식생구성비율 등에 미치는 영향을 구명하였다. 다량료소 양분을 동일 량 시비한 조건에서 7 수준의 미량요소 조합시비는 T$_1$; 대조구, T$_2$; Fe, T$_3$; Fe+Mn, T$_4$； Fe＋Mn＋Cu, T$_{5}$; Fe+Mn+Cu＋Zn, T$_{6}$；Fe+Mn+Cu＋Zn+Mo 및 T$_{7}$； Fe+Mn+Cu+Zn+Mo+B로 하였다. 본 II집에서는 조합시비가 목초의 건물수량 및 식생구 성비율/경합지수 특성 등에 미치는 영향을 검토하였다. 1. 조합시비가 수량에 미치는 효과는 초정, 재배방법(단파/혼파), 추파(특히 N) 및 예취 회수에 따라서 차이를 보였다. 조합시비의 효과가 orchardgrass보다 white clover(특히 혼파재배)에서 더 크게 나타났다. 두 목초 공히 T$_{7}$ 에서 가장 높은 수량을 보였으며 붕소(B)가 상대적으로 중요한 조정자 역할을 한 것으로 보였다. 2. 단파재배에서 두 목초의 수량은 T$_{7}$과 T$_2$에서 높았으며 그리고 T$_3$와 T$_{6}$ 에서 낮았다. Fe/Mn/Cu/Zn, Fe/Mo, Mo/B 및 ∑양이온/∑음이온간 비율이 상대적으로 조화된 T$_{7}$에서 수량이 가장 양호하였다. 그리고 Fe${\times}$Mn${\times}$Mo${\times}$B 간다종 교호작용이 있으며 이 때 B의 조정자 역할이 큰 것으로 보였다. white clover에 대한 이러한 효과는 추파 시보다 무추파(특히 N) 시에 더 크게 나타났다. 3. 혼파재배에서는 조화된 조합시비는 white clover의 식생구성비율과 수량제고에 상대적으로 더 긍정적 이였다. 반면에 orchardgrass는 반대적인 경향을 보였고(특히 무추비 시), 단지 T$_{7}$에서만 대조구(T$_1$)와 비슷한 수량을 보였다.다.한 수량을 보였다.

• Journal of Electrochemical Science and Technology
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• 제13권1호
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• pp.120-127
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• 2022

Molybdenum disulfide (MoS₂) has been widely used as a catalyst for the bifunctional activities of hydrogen and oxygen evolution reactions (HER and OER). Here, we investigated size dependent HER and OER performance of MoS₂. The smallest size (90 nm) of MoS₂ exhibits the lowest overpotential of -0.28 V at -10 mAcm^-2 and 1.52 V at 300 mAcm^-2 with the smallest Tafel slopes of 151 and 176 mVdec^-1 for HER and OER, respectively, compared to bigger sizes (2 ㎛ and 6 ㎛) of MoS₂. The better HER and OER performance is attributed to high electrochemical active surface area (6 × 10^-4 cm²) with edge sites and low charge transfer resistance (18.1 Ω), confirming that the smaller MoS₂ nanosheets have the better catalytic behavior.

• Tribology and Lubricants
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• 제12권1호
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• pp.15-21
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• 1996

Friction and wear properties of MoS$_2$ bonded films were studied using the Falex testing machine, and their properties were evaluated in terms of the life and the load carrying capacity of the films. MoS$_2$ bonded films were formulated from the mixtures of MoS$_2$ solid particles and epoxyphenol resin, and they were applied onto AISI 4130 steel surface by dipping method to form lubricating bonded films. The results of the life and the load carrying capacity of the films showed that films were mainly affected by the surface temperature arisen from the frictional heat at the contact surface. To obtain enhanced tribological properties of the films, various combinations of solid lubricants and additives with a basic polymer resin were attempted and evaluated. The effects of surface pretreatment, such as sand blast or Zn-phosphating, were also investigated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.637-642
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• 2003

The Modified 9Cr-1Mo steel identified as T91, P91 and F91 in the ASME specification has been widely used for the construction of modern power plants. The available data on the influence of process parameters during manufacturing and fabrication on its properties are not sufficient. In this study, the influence of various thermal cycles on the hardness and the creep rupture strength was analyzed in the base metal and the weldments made in tube and pipe of a Mod.9Cr-1Mo steel. The low hardness, 155Hv, showed low creep rupture strength below the allowable stresses of T91 base metal in the ASME specification. This low value was attributed to the fully recovered dislocation structure and the weakening of precipitation hardening associated with the abnormal thermal cycles.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.231-236
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• 2001

A newly developed Advanced Indentation System (AIS), which is a portable and nondestructive system for evaluating tensile properties, was used to measure mechanical behavior of materials used under high temperature and pressure conditions. This test measures indentation load-depth curve during indentation and analyzes the mechanical properties related to deformation and fracture. Aging effects of Cr-Mo and Cr-Mo-V steel at high temperature were simulated. Tensile properties including yield strength and tensile strength at various temperature are obtained from the test. For all test materials and conditions, the AIS-derived results were in good agreement with those from conventional standard test method. Examples of the test results ate given and potential applications of the AIS to assess the integrity of aging structures are briefly discussed.