• 열처리공학회지
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• 제7권3호
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• pp.184-189
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• 1994

The heat treatment charaterristic of SCM 440 and B 16 steels has been investigated in various condition(A, B and C) to the effect of heat treatment on mechanical properties, and the following results were obtained. 1. We are obtained a good nitriding characteristic in bainitic structure than other heat treatment cycle in our experiment. 2. Fatigue characteristic has shown in order of B)C)A condition as heat treatment cycle. 3. The effective hardening depth and fatigue characteristic has been excellented in B 16 than SCM 440 after the nitriding and Q. T for Band C condition. 4. Nitriding depth has been increased in addition of Cr, V and the nitriding efficiency is increased as easiness of banite formation to wide range of cooling rate by addition of Mo. 5. The depth of compound layer in parallel surface, notched slop plane and notched bottom has been varied to the nitriding depth of 5, 4 and 3 ${\mu}$ in relatively uniform pattern after 10h nitriding treatment for SCM 440 into A condition.

• 약학회지
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• 제38권5호
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• pp.614-620
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• 1994

Following the study on the fermentation conditions influencing the production of vitamin $B_{12}$ by Propionibacterium shermanii(Korean J Biotechnol. Bioeng. 7,126-131, 1992), the effects of some factors supplemented in the medium on the production of vitamin $B_{12}$ were studied. Maximum production of vitamin $B_{12}$ was observed when $Co^{+2}$ was supplemented at the concentration of 2-4 ppm in the fermentation medium. Increase of the supplemented $Co^{+2}$ to 12 ppm did not inhibit the growth of the organism, but it accelerated the lysis of the organism. In the literature, peptone was reported to activate the biosynthesis of vitamin $B_{12}$. Examination of the effect of peptone on the growth and the production of vitamin $B_{12}$ showed that at early stage more vitamin$B_{12}$ was observed in the supplemented medium, but no difference was observed in the later stage of fermentation. Examination of the time for addition and the amount of 5,6-dimethylbenzimidazole, a precursor known to influence the production of vitamin $B_{12}$, showed that a maximum yield of vitamin $B_{12}$ was observed when 15 mg/L was added to the fermentation medium after 2 days' incubation. The effect was comparable with the increase of the production of vitamin $B_{12}$ when the fermentation condition was changed to aerobic condition after 2 days' culture under anaerobic condition.

• East Asian mathematical journal
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• 제33권1호
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• pp.103-113
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• 2017

We provide quantitative two weight estimates for the commutator of the Hilbert transform under certain conditions on a pair of weights (u, v) and b in $Carl_{u,v}$. In [10] and [11], Bloom's inequality is shown in a modern setting, and the boundedness of the commutators is provided by assuming both weights u, v are $A_2$ and $b{\in}BMO_{\rho}$. In the present paper we show that the condition on b can be replaced by $Carl_{u,v}$ by using the joint $A^d_2$ condition.

• 대한기계학회논문집B
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• 제23권6호
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• pp.761-768
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• 1999

This paper is studied to find the optimum condition of double-inlet Sirocco fan installed in an indoor PAC for low noise operation by the Taguchi method. The goal of this study is to obtain the best combination of each control factor which results in a desired flowrate of Sirocco fan with minimum variability. In this study, the parameter design of the Taguchi method is adopted for robust design by the dynamic characteristic analysis using orthogonal arrays and S/N ratios. The flowrate measurements are conducted by using a multiple-nozzle-type fan tester according to the orthogonal array L9($3^4$). The results of this study can be summarized as follows ; (i) The optimum condition of control factor is a set of where A is an inner to outer diameter ratio($D_1/D_2$), B is a width to outer diameter ratio($L/D_2$), C is a blade attachment angle(${\theta}$) and D is a number of blade(Z), (ii) The flowrate under the optimum condition satisfies the equation $y=0.0384{\cdot}M$ where M is a signal factor, namely number of revolution. The flowrate performance improves about 7.3% more largely as compared with the current condition, which results in about 35RPM reduction of number of revolution for the target flowrate $18.5m^3/min$, and (iii) The sensitivity analysis shows that the major factors in contribution to flowrate performance are A, B, and D ; the percentage contributions of each control factor are 44.01%(Z), 26.77%($D_1/D_2$) and 20.42%($L/D_2$).

• 대한기계학회논문집B
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• 제26권7호
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• pp.937-944
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• 2002

An experimental study has been conducted to investigate the heat/mass transfer characteristics within a square film cooling hole with asymmetric inlet now condition. The asymmetric inlet now condition is achieved by making distances between side walls of the secondary now duct and the film cooling hole different; one side wall is $2D_h$ apart from the center of the film cooling hole, while the other side wall is $1.5D_h$ apart from the center of the film cooling hole. The heat/mass transfer experiments for this study have been performed using a naphthalene sublimation method and the now field has been analyzed by numerical calculation using a commercial code. Swirl now is generated at the inlet region and the heat/mass transfer pattem with the asymmetric inlet now condition is changed significantly from that with the symmetric condition. In the exit region, the effect of mainstream on the inside hole now is reduced with the asymmetric condition. The average heat/mass transfer coefficient is higher than that with the symmetric condition due to the swirl now generated by the asymmetric inlet condition.

• Reproductive and Developmental Biology
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• 제30권2호
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• pp.115-118
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• 2006

Cyclin B1 is known to reflect the M-phase promoting factor (MPF), a universal regulator of G2/M-phase transition, activity during the process of oocytes maturation. To investigate whether culture condition affects the maturation rate and the expression of cyclin B1 protein, bovine immature oocytes are stimulated and cultured according to the following protocols: Experiment 1: denuded oocytes (denude) only, COC only, denuded oocytes+granulosa cells (denude+GCs) and COC+GCs; Experiment 2: no-activation (control), 7% ethanol for 5 min and $10{\mu}l/ml$ ionomycin for 5 min at immediately before maturation. The maturation rates of denude and no-activation group were significantly lower in both experiments (P<0.05), respectively. Co-culture or stimulation method in bovine immature oocytes culture increases the cyclin B1 expression significantly in both experiments (P<0.05). Based on these results, culture condition affects the maturation rate and the expression of cyclin B1 protein during the first meiotic maturation in bovine immature oocytes.

• Korean Journal of Mathematics
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• 제26권3호
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• pp.459-465
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• 2018

Recently, Li et al proved that ${\Phi}$ which satisfies the following condition on factor von Neumann algebras $${\Phi}([[A,B]_*,C]_*)=[[{\Phi}(A),B]_*,C]_*+[[A,{\Phi}(B)]_*,C]_*+[[A,B]_*,{\Phi}(C)]_*$$ where $[A,B]_*=AB-BA^*$ for all $A,B{\in}{\mathcal{A}}$, is additive ${\ast}-derivation$. In this short note we show the additivity of ${\Phi}$ which satisfies the above condition on prime ${\ast}-algebras$.

• Kyungpook Mathematical Journal
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• 제47권3호
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• pp.311-322
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• 2007

This paper deals with space Beltrami system with three characteristic matrices in even dimensions, which can be regarded as a generalization of space Beltrami system with one and two characteristic matrices. It is transformed into a nonhomogeneous $p$-harmonic equation $d^*A(x,df^I)=d^*B(x,Df)$ by using the technique of out differential forms and exterior algebra of matrices. In the process, we only use the uniformly elliptic condition with respect to the characteristic matrices. The Lipschitz type condition, the monotonicity condition and the homogeneous condition of the operator A and the controlled growth condition of the operator B are derived.

• 한국응용과학기술학회지
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• 제41권1호
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• pp.69-82
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• 2024

본 연구의 목적은 640 nm LED 조사와 아로마테라피가 목 피부 상태에 미치는 영향을 체계적으로 평가하고 비교하는 것이다. 20명의 여성 참여자를 대상으로 A그룹(640 nm LED 조사 + 아로마테라피)와 B그룹(640 nm LED 조사만)으로 나뉘어, 주 2회씩, 총 8회의 실험을 진행하였다. 실험 결과, 수분 함량은 A그룹(p<0.01)과 B그룹(p<0.001) 모두 유의하게 나타났으며, 주름 지수는 A그룹(p<0.01)과 B그룹(p<0.05) 모두 유의하게 나타났다. 또한, 치밀도 변화는 A그룹(p<0.001)과 B그룹(p<0.05) 모두 유의하게 나타났으며, 탄력 변화는 A그룹(p<0.001)과 B그룹(p<0.001) 모두 유의하게 나타났다. 피부색 변화는 A그룹에서는 (p>0.05) 유의하지 않았고, B그룹에서는 (p<0.05) 유의하게 나타났다. 기미 및 색소 침착 변화는 A그룹에서 (p<0.05) 유의하게 나타났으며, B그룹에서는 (p>0.05) 유의하지 않았다. 이러한 결과는 아로마테라피와 640 nm LED 조사를 병행하는 것이 목 피부 상태를 향상시키는 데 높은 효과를 나타낼 수 있음을 시사한다.

• 한국주조공학회지
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• 제20권2호
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• pp.89-96
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• 2000

The effects of modification processing on the refinement of primary Si and the wear behavior of hyper-eutectic Al-Si alloys have been mainly investigated. Refining effects of primary Si in Al-17%Si alloy was more efficient than that of B.390 alloy. Optimum condition of getting the finest primary Si microstructure was when AlCuP modifier is added into the melt at $750^{\circ}C$ and held it at $700^{\circ}C$ for 30 minutes. Wear loss in the specimens of as-cast condition decreases as the size of primary Si decreases, in the order of B.390 alloy, B.390 alloy with AlCuP addition, Al-17%Si alloy and Al-17%Si alloy with AlCuP addition. Wear loss in the aged condition of Al-17%Si alloy, B.390 alloy and B.390 alloy with AlCuP addition decreased due to the increase of compressive residual stress in the matrix by the aging treatment. While, wear loss increased in the aged specimens of Al-17%Si alloy with AlCuP addition and Hepworth addition in which compressive residual stress decreases by the aging treatment. Therefore, it is assumed that higher compressive residual stress in the matrix can reduce the wear loss in composite materials such as hyper-eutectic Al-Si alloys.