• 시스템엔지니어링학술지
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• 제15권1호
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• pp.43-50
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• 2019

Statistical hypothesis tests are important for quantifying answers to questions about samples of data. The Step Process of Statistical Hypothesis Testing; state the null hypothesis, State the alternate hypothesis, State the alpha level, Find the z-score associated with alpha level, Find the test statistic using this formula, If the calculated t distribution value from the data is larger than the t distribution value of alpha level, then you are in the Rejection region and you can reject the Null Hypothesis with ($1-{\alpha}$) level of confidence.

• 대한수학회보
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• 제56권5호
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• pp.1297-1314
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• 2019

In this work, we investigate the following fractional boundary value problems $$\{_tD^{\alpha}_T({\mid}_0D^{\alpha}_t(u(t)){\mid}^{p-2}_0D^{\alpha}_tu(t))\\={\nabla}W(t,u(t))+{\lambda}g(t){\mid}u(t){\mid}^{q-2}u(t),\;t{\in}(0,T),\\u(0)=u(T)=0,$$ where ${\nabla}W(t,u)$ is the gradient of W(t, u) at u and $W{\in}C([0,T]{\times}{\mathbb{R}}^n,{\mathbb{R}})$ is homogeneous of degree r, ${\lambda}$ is a positive parameter, $g{\in}C([0,T])$, 1 < r < p < q and ${\frac{1}{p}}<{\alpha}<1$. Using the Fibering map and Nehari manifold, for some positive constant ${\lambda}_0$ such that $0<{\lambda}<{\lambda}_0$, we prove the existence of at least two non-trivial solutions

• 한국해양공학회지
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• 제8권1호
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• pp.114-122
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• 1994

X-ray stress constant, K, was determined for the diffraction line of (211)plane by using Cr-K$\alpha$ radiation. K was -340.87 MPa/deg. Fatigue crack propagation tests of SS41 steel were conducted under stress ratios of 0.1, 0.3 and 0.5. The half-value breadth of X-ray diffraction profile was measured at and beneath the fracture surface. The half-value breadth, B, on the fracture surface was found to increase with increasing $K_max$. The value of B was influenced by stress ratio in SS41 steel. The half-value breadth took the maximum value at the borden of reversed plastic zone, while it approached to the initial (pre-fatigue) value near the boundary of monotonic plastic zone. The maximum depth of the plasticzone was evaluated on the basis of the half-value breadth distribution. The depth $\omega$$_y$ is related to $K_max$by the following equation : $\omega$$_y$ = $\alpha$($K_max$/$\sigma$$_y$$)^2$ where .sigma.$\sigma$$_y$ is the yield strength obtength obtained in tension test .alpha.is 0.136 for SS41 steel.

• 한국정밀공학회지
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• 제1권1호
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• pp.50-58
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• 1984

In the present paper are calculated and compared the stresses on the normal tools and the restricted tools which have three various rake angles by Least Square Method. The results obtained are summerized as follows. The tool displacement at rake angle .alpha. = 12 .deg. and .alpha. = 0 .deg. is positive value in the principal cutting direction and negative value in the feed direction. At rake angle .alpha. = -12 .deg. the displacement is negative value in both of directions. The principal stress of the restricted and normal tool is maximum at the tip of the tool, the shear stress is maximum after a certain distance from the tip. The result of FEM and P.E method shows that in the range of rapid decreasing of normal stress of the tool edge, the shear stress is maintaining a certain value. This is due to the friction characteristic of the chip.

• 한국응용과학기술학회지
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• 제9권1호
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• pp.47-54
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• 1992

The natural antioxidant such as e-tocopherol and synthetic antioxidant BHT were used to compare antioxidative effects of those antioxidants from the physico-chemical properties and fatty acid composition changes in the soybean oil due to number of frying. The composition of frying oil were consisted of a group(Fresh oil), B gorup(Fresh oil added with 0.05% ${\alpha}$-tocopherol), C group(Fresh oil added with 0.2% ${\alpha}$-tocopherol), D group(Fresh oil added with 0.1% BHT), E group(Tocopherol removed oil from oil by active alumina column chromatography The results obtained were as follws : 1. The color was determined by the Lovibond colorimeter color intensity increased number of frying oil. 2, The acid value, TBA value and Carbonyl value were increased number of frying oil. 3. Natural antioxidants less effective than BHT but effect of ${\alpha}$-tocopherol was very similar to that of BHT. 4. The order of antioxidative effect was 0.1% BHT, 0.2% ${\alpha}$-tocopherol, 0.05% ${\alpha}$-tocopherol, fresh oil, tocopherol remove oil.

• 대한기계학회논문집
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• 제9권5호
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• pp.548-554
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• 1985

본 논문에서는 디이젤기관의 연소소음의 저감을 최종목표로 하여 Wiebe의 연 소함수에 의해 근사시킨 열발생속도의 변화가 디이젤기관의 연소소음 및 도시열효율에 미치는 영향에 관하여 수치실험을 통하여 해석검토하였다.

• Korean Journal of Acupuncture
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• 제23권1호
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• pp.37-44
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• 2006

Objective : To investigate the effects of Poncirus trifoliata Pharmacopuncture on lowering lipid and contents of serum tumor necrosis $factor-{\alpha}$ $(TNF-{\alpha})$ and interleukin-6 (IL-6) in hyperlipidemic rats. Methods : Triglyceride, total cholesterol, $TNF-{\alpha}$, and IL-6 levels in Poncirus trifoliata Pharmacopuncture groups were compared with those in the control group. Results : Concentration of triglyceride and total cholesterol in plasma was decreased in the Poncirus trifoliata Pharmacopuncture groups. In Poncirus trifoliata Pharmacopuncre groups, plasma LDL-cholesterol showed a lower value and HDL-cholesterol showed a higher value than those of the control group. Contents of $TNF-{\alpha}$ was decreased in the Poncirus trifoliata Pharmacopuncture groups. Contents of IL-6, however, were not significantly different. Conclusions : The results suggest that Poncirus trifoliata Pharmacopuncture may have an impact on lipid metabolism to potentially prevent development of diabetes mellitus and accompanying cerebrovascular diseases.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권5호
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• pp.241-247
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• 2004

The composites were fabricated 61 vol.%$\alpha$-$\alpha$-SiC and 39vol.% WC powders with the liquid forming additives of 12wt% $Al_2$O$_3$＋Y$_2$O$_3$ by pressureless annealing at 1700, 1800, 190$0^{\circ}C$ for 4 hours. The result of phase analysis of composites by XRD revealed $\alpha$-SiC(2H), WC, and YAG(Al$_{5}$ Y$_3$O$_{12}$ ) crystal phase. The relative density, the flexural strength, fracture toughness and Young's modulus showed respectively the highest value of 99.4%, 375.76㎫, 5.79㎫ㆍm$\frac{1}{2}$, and 106.43㎬ for composite by pressureless annealing temperature 190$0^{\circ}C$ at room temperature. The electrical resistivity showed the lowest value of 1.47${\times}$10$^{-3}$ $\Omega$$.$cm for composite by pressureless annealing temperature 190$0^{\circ}C$ at $25^{\circ}C$. The electrical resistivity of the $\alpha$-SiC-WC composites was all positive temperature cofficient resistance (PTCR) in the temperature ranges from $25^{\circ}C$ to 50$0^{\circ}C$.

• 한국임상수의학회지
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• 제19권3호
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• pp.342-349
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• 2002

Vitamin D is one of important factors involved in the regulation of bone metabolism. In osteoporosis, the therapeutic effect of vitamin D on the healing process has still been controversial. To conform the effect of $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ on osteoporosis, the change of serum calcium, serum phosphorus, serum alkaline phosphatase, bone mineral density and bone mineral content of osteoporotic tibia were examined comparatively in normal control group(positive control), CFA control(negative control), CFA+$1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.01 ug/kg group and CFA+$1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group after osteoporosis was induced by single injection of complete Freund's adjuvant(CFA) in rats. In change of serum calcium. the significantly increased value was shown on 2nd and 5th week(P< 0.05) after treatment in $1{\alpha}$, 25 dihydroxy-vitamin D$_3$ 0.01 ug/kg group and on 3rd week(P<0.05) after treatment in $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group than CFA control. In change of serum phosphorus, the significantly increased value was shown on 2nd week(P<0.05) after treatment in $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.01 ug/kg group and on 3rd and 4th week(P<0.05) after treatment in $1{\alpha}$, ,25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group than CFA control. The value of bone mineral density and bone mineral content of tibia was increased in both $1{\alpha}$,25 dihydroxy-vitamin $D_3$ 0.01 ug/kg group and $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group than CFA control, and the increase rate of that was higher in $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.1 ug/kg group than $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ 0.01 ug/kg group. Considering above findings collectively, it was considered that $1{\alpha}$, 25 dihydroxy-vitamin $D_3$ was effective in preventing the complete Freund's adjuvant-induced osteoporotic decrease of bone mass.

• Elastomers and Composites
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• 제47권1호
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• pp.18-22
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• 2012

실란처리된 실리카가 천연고무 복합소재 내에서 실리카 간의 구조 발달 상수 ${\alpha}_F$에 미치는 영향을 비교하였다. 기존의 질량분율로 표시하던 Wolff의 방법을 본 실험에서는 부피분율을 사용하여 Wolff의 값과 비교하였다. 두 표현방식 모두 실리카의 함량이 증가할수록 ${\alpha}_F$값이 증가하는 경향을 보였다. 또한 부피분율로 표현하였을 시 ${\alpha}_F$값 간의 차이가 더욱 커지는 것을 관찰하였다. 따라서 부피분율로 표현하는 것이 ${\alpha}_F$값의 차이를 관찰하는데 있어서 기존에 질량분율을 사용하는 Wolff의 방법 보다는 차이를 뚜렷하게 나타낼 수 있다는 것을 관찰하였다. 또한 촉진제의 양을 변화시켜 관찰한 ${\alpha}_F$값의 변화와 비교하였다.