• 대한화장품학회지
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• 제23권3호
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• pp.24-38
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• 1997

Using the all-trans-retinol which is double-capsulated with matrix, we investigated its stability and the change of the epidermal thickness. The proprietary MDC comprise two steps of capsulation of retinol, i.e., primary microcapsulation with collagen and then secondary capsulation with gellan gum. We compared the activity of all-trans-retinol in various forms such as (1) simply in O/W, (2) in W/O emulsion, (3) in primary capsulted form in O/W emulsion, or (4) in MDC in O/W emulsion. After storage at 45$^{\circ}C$ for 4 weeks, retinol in MDC in O/W emulsion retained 92% of the activity compared to the standard material upon HPLC analysis, whereas the primary capsule gave 70%, the O/W emulsion form 47% and the W/O emulsion 78%. The retinol in MDC in O/W induced the siginificant increase in epidermal thickness compared to the vehicle.

• 대한수학회보
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• 제51권6호
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• pp.1851-1861
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• 2014

We introduce the concept of w-zero-divisor (w-ZD) rings and study its related rings. In particular it is shown that an integral domain R is an SM domain if and only if R is a w-locally Noetherian w-ZD ring and that a commutative ring R is w-Noetherian if and only if the polynomial ring in one indeterminate R[X] is a w-ZD ring. Finally we characterize universally zero divisor rings in terms of w-ZD modules.

• 제어로봇시스템학회논문지
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• 제6권10호
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• pp.888-893
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• 2000

This paper deals with the development of an automatic design software for DC servo motor control, which provides good performance with rapid response and velocity control accuracy. In the proposed method, the design is automatically executed using Matlab, and iterative learning control algorithms are used in the design process. We applied this method to 50W, 100W, 200W, 300W, 500W, 750W, 1.8kW and 4.5kW DC servo motors which are widely used in the industry. We compare the results of the manual tuning design method with that of the automatic design method presented in this paper. From the experimental results, we can find that the performance of the proposed method is better than that of the manual tuning design method.

• 전기전자학회논문지
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• 제21권3호
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• pp.252-255
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• 2017

고온자전합성과 후열처리 공정으로 $Mo_xW_{1-x}Si_2$ 발열체를 제조하였다. $Mo_xW_{1-x}Si_2$ 발열체의 신뢰성을 검증하기 위해 가속수명시험을 수행하였으며, 수명시간을 Minitab 프로그램으로 추정하였다. 또한, 가속수명시험 후의 $Mo_xW_{1-x}Si_2$ 발열체의 고장분석을 전기적과 구조적 특성으로부터 수행하였다. 그 결과, $Mo_xW_{1-x}Si_2$ 발열체의 지배적인 고장 유형은 발열체 내부의 크랙 형성과 $SiO_2$ 보호층의 박리임을 확인하였다.

• 원자력산업
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• 제5권10호통권32호
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• pp.58-64
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• 1985

일본원자력산업회의가 1985년6월말 현재 세계에서 운전중, 건설중, 계획중인 원자력발전소를 조사한 결과에 따르면 운전중인 원전은 336기, 2억3,658만1,000kW이고, 건설중이 184기, 1억7,769만1,000kW, 계획중이 132기, 1억 3,310만9,000kW로서 합계 652기, 총용량 5억 4,738만1,000kW(Gross전기출력)이다.

• Journal of applied mathematics & informatics
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• 제20권1_2호
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• pp.35-59
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• 2006

In this paper, we generalized the results of [23, 26], and get the results of the condition number of the W-weighted Drazin-inverse solution of linear system W AW\chi=b, where A is an $m{\times}n$ rank-deficient matrix and the index of A W is $k_1$, the index of W A is $k_2$, b is a real vector of size n in the range of $(WA)^{k_2}$, $\chi$ is a real vector of size m in the range of $(AW)^{k_1}$. Let $\alpha$ and $\beta$ be two positive real numbers, when we consider the weighted Frobenius norm $\|[{\alpha}W\;AW,\;{\beta}b]\|$(equation omitted) on the data we get the formula of condition number of the W-weighted Drazin-inverse solution of linear system. For the normwise condition number, the sensitivity of the relative condition number itself is studied, and the componentwise perturbation is also investigated.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.105-109
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• 2004

This study was conducted to investigate the potential origin of Weissella species, which were found in ingredients of kimchi, such as salted Chinese cabbage, radish, green onion, red pepper powder, pickled shrimps, garlic, and ginger. Ten strains of Weissella species (Weissella thailandensis, W. kimchii, W. koreensis, W. minor, W. halotolerans, W. hellenica, W. kandleri, W. confusa, W. viridescens, and W. paramesenteroides) and lactic acid bacteria isolated from ingredients of kimchi were analyzed by SDS-PAGE of whole-cell proteins. Several strains with patterns identical to those of Weissella kimchii were isolated from green onion. On the basis of biochemical characteristics and 16S rDNA sequence comparisons, these strains were identified as Weissella kimchii, suggesting green onion as a major origin of Weissella kimchii found in kimchi.

• Nuclear Engineering and Technology
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• 제31권6호
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• pp.561-571
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• 1999

Microstructure and mechanical properties of five Cr-Mo steels for nuclear industry applications have been investigated. Transmission electron microscopy, energy dispersive spectrometer, differential scanning calorimeter, hardness, tensile, and impact test were used to evaluate the Cr and W effect on the microstructure and mechanical properties. Microstructures of Cr-Mo steels after tempering are classified into three types : bainitic 2.25Cr-lMo steel, martensitic Mod.9Cr-lMo, HT9M, and HT9W steels, and dual phase HT9 steel. The majority of the precipitates were found to be M$_{23}$C$_{6}$ carbides. As minor phases, fine needle-like V(C,N), spherical NbC, fine needle-like Cr-rich Cr$_2$N, and Cr-rich M$_{7}$C$_3$were also found. Addition of 2wt.% W in Cr-Mo steels retarded the formation of subgrain and dissolution of Cr$_2$N precipitates. Hardness and ultimate tensile strength increased with increasing Cr content. Though Cr content of HT9W steel was lower than that of HT9 steel, the hardness of HT9W was higher due to the higher W content. W added HT9W steel had the highest ultimate tensile strength above $600^{\circ}C$. But impact toughness of W added steel (HT9W) and high Cr steel (HT9) was low.w.w.

• 한국분말재료학회지
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• 제27권4호
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• pp.293-299
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• 2020

W₂C is synthesized through a reaction-sintering process from an ultrafine-W and WC powder mixture using spark plasma sintering (SPS). The effect of various parameters, such as W:WC molar ratio, sintering temperature, and sintering time, on the synthesis behavior of W₂C is investigated through X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) analysis of the microstructure, and final sintered density. Further, the etching properties of a W₂C specimen are analyzed. A W₂C sintered specimen with a particle size of 2.0 ㎛ and a relative density over 98% could be obtained from a W-WC powder mixture with 55 mol%, after SPS at 1700℃ for 20 min under a pressure of 50 MPa. The sample etching rate is similar to that of SiC. Based on X-ray photoelectron spectroscopy (XPS) analysis, it is confirmed that fluorocarbon-based layers such as C-F and C-F2 with lower etch rates are also formed.

• Journal of Pharmaceutical Investigation
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• 제35권1호
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• pp.33-38
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• 2005

Recently increasing attention has been focused on solid lipid nanoparticles (SLN) as a parenteral drug carrier due to its numerous advantages that can come from both polymeric particle and fat emulsions, together with the possibility of controlled release and increasing drug stability. Lipophilic drugs such as paclitaxel, cyclosporin A, and all-trans retinoic acid have been successfully entrapped in SLN but the incorporation of hydrophilic drugs in SLN is very limited because of their very low affinity to the lipid. Therefore, as a new approach to improve the loading of hydrophilic drugs, a w/o/w emulsion technique has been developed. The primary objective of the current study was to improve the loading efficiency of a model hydrophilic drug, glycine (Log P = -3.44) into SLN. The proposed preparation process is as follows: A heated aqueous phase consisting of 0.1 ml of glycine solution in water (100 mg/ml), and poloxamer 188 (5 mg) were then added to a molten oil phase containing precirol (100 mg) and lecithin (5 mg). This mixture was dispersed by sonicator, leading to a w/o emulsion. A double emulsion (w/o/w) was formed after the addition of 2% poloxamer solution to the above dispersed system. After cooling the double emulsion, solid lipid nanosuspensions were successfully formed. The lipid nanoparticles had the mean particle size of 441.25 nm, and the average zeta potential of -20.98 mV. The drug loading efficiency was measured to be 8.54% and the drug loading amount was measured to be 0.92%. The w/o/w emulsion method showed an increased loading efficiency compared to conventional o/w emulsion method.