• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.303-304
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• 2005

Add $Li_2CO_3$ to $(Ba_{0.6}Sr_{0.4})$ $TiO_3$ powder to lower sitering temperature in this research, made thick film by tape casting method. Investigated about sitering temperature and physical properties that added $Li_2CO_3$ Even if lower sitering temperature about $200^{\circ}C$ adding $Li_2CO_3$ 10wt.%, density was near to 5.7$g/cm^3$ that is theoretical values, and crystal structure examined as perobeuseukaiteu senior after sintering.

• 대한수학회지
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• 제48권2호
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• pp.301-309
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• 2011

Let R = $Mat_2(F)$ be the ring of all 2 by 2 matrices over a finite field F, X the set of all nonzero, nonunits of R and G the group of all units of R. After investigating some properties of orbits under the left (and right) regular action on X by G, we show that the graph automorphisms group of $\Gamma(R)$ (the zero-divisor graph of R) is isomorphic to the symmetric group $S_{|F|+1}$ of degree |F|+1.

• Bulletin of the Korean Chemical Society
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• 제16권12호
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• pp.1203-1208
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• 1995

Theoretical studies of the effect of the nonleaving group (RY) on the breakdown mechanism of the tetrahedral anionic intermediate, T-, formed by the addition of a less basic phenoxide nucleophile (X) to phenyl benzoates with a more basic phenoxide leaving group (Z) have been carried out using the PM3 MO method. The identity acyl transfer reactions (X=Z) are facilitated by an electron-withdrawing RY whereas they are inhibited by an electron-donating RY group. The results of non-identity acyl transfer reactions indicate that a more electron-donating RY group leads to a greater lowering of the higher barrier, TS2, with a greater degree of bond cleavage, and a greater negative charge development on the phenoxide oxygen atom, whereas the opposite is true for a more electron-withdrawing RY group, i.e., leads to a greater lowering of the lower barrier, TS1. The results provide theoretical basis for the signs of ρXY(>0) and ρYZ(<0) observations.

• 한국작물학회지
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• 제38권1호
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• pp.8-14
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• 1993

가공 적성면에서 가장 중요한 품질요인인 단백질의 양과 질을 육종 목표로 했을 때 잡종 후기 세대에서의 선발 효과를 보기 위하여 조광 x Lancota, 수원 210호 x Atlas 66의 두 조합의 후대를 공시하여 단백질함량, 심전가, Mixogram pattern, 제빵 특성을 검토하였다. 1. F4 세대에서 선발된 고단백 집단의 단백질함량은 저단백 집단에 비해 F5 세대에서는 유의성 있게 높은 값을 보였으나 F6 에서는 유의성 있는 차이를 보이지 않았다. 2. 심전가 고단백은 경질 Group과 저단백 연질 Group간에서만 차이가 인정되었다. 3. F6 세대에서 개체별로 수확하여 단백질함량과 심전가를 분석한 결과, 분포영역은 저단백 연질, 저단백 경질, 고단백 연질, 고단백 경질 Group의 순서로 단백질 함량 및 심전가 높은 쪽으로 이동되었으며 이러한 경향은 수원 210호 x Atlas 66 조합에서 더욱 뚜렷하였다. 4. 밀가루 반죽의 특성을 나타내는 Mixogram pattern은 각 특성 Group별로 고유의 형태를 보여 선발의 효과를 볼 수 있었다. 5. F6 세대의 제빵 특성은, 수원 210호 x Atlas 66 조합은 고단백 경질 Group이 저단백 연질 Group에 비해 빵의 부피가 큰 것으로 나타났으나 조광 x Lancoa 조합은 유의성 있는 차이를 보이지 않았다.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3743-3747
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• 2011

Kinetic studies on the reactions of Y-S-aryl phenyl phosphonochloridothioates with X-pyridines have been carried out in MeCN at $55.0^{\circ}C$. The Hammett and Bronsted plots for substituent X variations in the nucleophiles are biphasic concave upwards with a break point at X = H. The Hammett plots for substituent Y variations in the substrates are biphasic concave upwards with a break point at Y = H, and the sign of ${\rho}_Y$ is changed from unusual negative (${\rho}_Y$ < 0) with the weaker electrophiles to positive (${\rho}_Y$ > 0) with the stronger electrophiles. The stepwise mechanism is proposed on the basis of the ${\rho}_X$, ${\beta}_X$, and ${\rho}_{XY}$ values as follows: a ratelimiting leaving group departure from the intermediate involving a frontside attack and product-like TS for the stronger nucleophiles and weaker electrophiles; a rate-limiting leaving group departure from the intermediate involving a backside attack and product-like TS for the weaker nucleophiles and electrophiles; a rate-limiting bond formation involving a frontside attack for the stronger nucleophiles and electrophiles; a rate-limiting bond formation involving a backside attack for the weaker nucleophiles and stronger electrophiles. The substituent effects of X and Y on the pyridinolysis mechanisms of $R_1R_2P$(=S)Cl-type substrates are discussed.

• Journal of Periodontal and Implant Science
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• 제46권6호
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• pp.415-425
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• 2016

Purpose: The present study investigated the impact of 2 different suture techniques, the conventional crossed mattress suture (X suture) and the novel hidden X suture, for alveolar ridge preservation (ARP) with an open healing approach. Methods: This study was a prospective randomized controlled clinical trial. Fourteen patients requiring extraction of the maxillary or mandibular posterior teeth were enrolled and allocated into 2 groups. After extraction, demineralized bovine bone matrix mixed with 10% collagen (DBBM-C) was grafted and the socket was covered by porcine collagen membrane in a double-layer fashion. No attempt to obtain primary closure was made. The hidden X suture and conventional X suture techniques were performed in the test and control groups, respectively. Cone-beam computed tomographic (CBCT) images were taken immediately after the graft procedure and before implant surgery 4 months later. Additionally, the change in the mucogingival junction (MGJ) position was measured and was compared after extraction, after suturing, and 4 months after the operation. Results: All sites healed without any complications. Clinical evaluations showed that the MGJ line shifted to the lingual side immediately after the application of the X suture by $1.56{\pm}0.90mm$ in the control group, while the application of the hidden X suture rather pushed the MGJ line slightly to the buccal side by $0.25{\pm}0.66mm$. It was demonstrated that the amount of keratinized tissue (KT) preserved on the buccal side was significantly greater in the hidden X suture group 4 months after the procedure (P<0.05). Radiographic analysis showed that the hidden X suture had a significant effect in preserving horizontal width and minimizing vertical reduction in comparison to X suture (P<0.05). Conclusions: Our study provided clinical and radiographic verification of the efficacy of the hidden X suture in preserving the width of KT and the dimensions of the alveolar ridge after ARP.

• 대한임상독성학회지
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• 제11권2호
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• pp.101-105
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• 2013

Purpose: This study was conducted in order to determine the relationship between the number of portable X-rays and the radiation exposure dose for emergency medical service providers working in the emergency department (ED). Methods: A prospective study was conducted from February 15, 2013 to May 15, 2013 in the ED in an urban hospital. Six residents, seven emergency medical technicians (EMT), and 24 nurses were enrolled. They wore a personal radiation dosimeter on their upper chest while working in the ED, and they stayed away from the portable X-ray unit at a distance of at least 1.8 m when the X-ray beam was generated. Results: The total number of portable x-rays was 2089. The average total radiation exposure dose of emergency medical service providers was $0.504{\pm}0.037$ mSv, and it was highest in the EMT group, 0.85(0.58-1.08) mSv. The average of the total number of portable X-rays was highest in the doctor group, 728.5(657.25-809). The relationship between the number of portable X-rays and the radiation exposure dose was not statistically significant(-0.186, p=0.269). Conclusion: Under the condition of staying away from the portable X-ray unit at a distance of least 1.8 m, the relationship between the number of portable X-rays and the radiation exposure dose was not statistically significant.

• Journal of Biosystems Engineering
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• 제39권1호
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• pp.11-20
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• 2014

Purpose: Walking type cultivator used for weeding generated excessive handle vibration as well as bouncing motion depending on the weeding speed. This research was conducted to define a design factor of the rotary weeding blades for reducing soil reaction forces as well as hand vibration. Methods: The motion and forces acting on the rotary blades were reviewed to find out the most influencing parameter on hand vibration. The installation angle (IA) of the blade was selected and analyzed to determine the condition of no reaction force less. For removing the unnecessary upward soil reaction, the design factor theory of weeding blade was suggested based on geometrics and dynamics. For evaluation of design factor theory, the experiment in situ was performed base on ISO 5349:1. The vibration $a_{hv}$ and theoretical value $X_{MF}$ were compared with two groups that one was positive group ($X_{MF}$ > 0) and the other was negative group ($X_{MF}$ < 0). Results: $X_{MF}$ was derived from rotational velocity, forward velocity, disk diameter, weeding depth, blade's width and IA of blade. Two groups had significant difference (p < 0.05). In aspect of the group mean total exposure duration, positive group was 17.53% bigger than negative group. When disk radius 100, 150 and 200 mm, minimum IAs were $4{\sim}27^{\circ}$, $3{\sim}15^{\circ}$ and $2{\sim}10^{\circ}$, respectively. A spread sheet program which calculated XMF was developed by Excel 2013. Conclusions: According to this result, minimum IA of weeding blade for soil reaction reduction could be obtained. For reduction hand-arm vibration and power consumption, minimum IA is needed.

• Nuclear Engineering and Technology
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• 제49권8호
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• pp.1610-1616
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• 2017

To validate the new Evaluated Nuclear Data File $(ENDF)/B-VIII.0{\beta}4$ library, 31 different critical cores were selected and used for a benchmark test of the important parameter keff. The four utilized libraries are processed using Nuclear Data Processing Code (NJOY2016). The results obtained with the $ENDF/B-VIII.0{\beta}4$ library were compared against those calculated with ENDF/B-VI.8, ENDF/B-VII.0, and ENDF/B-VII.1 libraries using the Monte Carlo N-Particle (MCNP(X)) code. All the MCNP(X) calculations of keff values with these four libraries were compared with the experimentally measured results, which are available in the International Critically Safety Benchmark Evaluation Project. The obtained results are discussed and analyzed in this paper.

• 호남수학학술지
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• 제10권1호
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• pp.11-21
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• 1988