• 한국해양공학회지
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• 제9권1호
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• pp.92-100
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• 1995

The effect of different anisotropy and stress ratio on fatigue crack propagation behavior was investigated under various stress ratio(R=-0.4, -0.2, 0.2, 0.2, 0.4) using pure titanium sheet used in aerospace, chemical and food industry. The rack closure behavior under constant load amplitude fatigue crack propagation test was examined. Fatigue crack propagation rate da/dN was estimated in terms of effective stress intensity factor range, $\Delta$K$_{eff}$, regardless of various stress ratio but was influenced by anisotropy. Also, it was found that the effect of anisotropy was considerably decreased but still not negligible when he da/dN was evaluated by a conventional parameter, $\Delta$$K_{eff}$/E and when the modified da/dN.$\sqrt{\varepsilon}_f$ was evaluated by $\Delta$$K_{eff}$/E. On the other hand, da/dN could be evaluated uniquely by effective new parameter, $\Delta$K$_{eff}$/$sigma_{ys}$, regardless of anisotropy, as int he following equation da/dN=C''[\frac{{\Delta}K_{eff}}{{\sigma}_{ys}}]^{n''}. And effective stress intensity factor range ratio, U was estimated by the following equation with respect to the ratio of reversed plastic zone size, $\Delta r_{p}$ to monotonic plastic zone size, $r_p$ regardless of stress ratio and anisotropy. U=-4.45$(\Delta r_{p}/r_{p})^{2}$+4.1$(\Delta r_{p}/r_{p})$+0.245_{p})$+0.245

• 한국가금학회지
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• 제34권3호
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• pp.181-185
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• 2007

본 연구는 델타-이미노레블린산(ALA)의 급여가 산란계의 생산성 및 계란 품질에 미치는 영향에 대해 알아보기 위하여 시험을 실시하였다. 사양 시험은 30주령 ISA Brown 144수를 공시하였으며 28일간 실시하였다. 시험 설계는 1) CON (기초 사료), 2) 0.05(기초 사료 + ALA 0.05%) 3) 0.1(기초 사료 + ALA 0.1%) 및 4) 0.2(기초 사료 + ALA 0.2%)로 4개 처리를 하여 처리당 4반복, 반복당 12수씩 완전 임의 배치하였다. 전체 사양 시험 기간 동안, 델타-아미노레블린산의 첨가 수준이 증가함에 따라 산란율의 감소가 나타났으나, 0.2% 첨가 수준에서 다시 증가하는 경향을 나타내었다(quadratic effect, P=0.01). 난중은 델타-아미노레블린산의 첨가 수준이 증가함에 따라 무게가 증가하였다(linear effect, P=0.01; quadratic effect, P=0.01). 난황색은 전체 사양 시험 기간 동안, 0.1% 첨가 수준까지 난황색이 높아지다가 0.2% 첨가 수준에서 낮아지는 경향을 나타내었다(quadratic effect, P=0.03). 델타-아미노레블린산의 첨가 수준이 증가함에 따라 혈액 내 hemoglobin 농도가 유의적으로 증가하였다(linear effect, P= 0.01). 결론적으로, 산란계에 델타-아미노레블린산의 급여는 난중 및 난황색 그리고 혈액 내 hemoglobin 농도를 증가시키는 것으로 사료된다.

• Steel and Composite Structures
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• 제13권6호
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• pp.501-519
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• 2012

As an alternative to current conventional force-based assessment methods, the energy-based seismic performance of a code-designed 20-storey high-rise steel building is evaluated in this paper. Using 3D nonlinear dynamic time-history method with consideration of additional material damping effect, the influences of different restoring force models and P-${\Delta}/{\delta}$ effects on energy components are investigated. By combining equivalent viscous damping and hysteretic damping ratios of the structure subjected to strong ground motions, a new damping model, which is amplitude-dependent, is discussed in detail. According to the analytical results, all energy components are affected to various extents by P-${\Delta}/{\delta}$ effects and a difference of less than 10% is observed; the energy values of the structure without consideration of P-${\Delta}/{\delta}$ effects are larger, while the restoring force models have a minor effect on seismic input energy with a difference of less than 5%, but they have a certain effect on both viscous damping energy and hysteretic energy with a difference of about 5~15%. The paper shows that the use of the hysteretic energy at its ultimate state as a seismic design parameter has more advantages than seismic input energy since it presents a more stable value. The total damping ratio of a structure consists of viscous damping ratio and hysteretic damping ratio and it is found that the equivalent viscous damping ratio is a constant for the structure, while the equivalent hysteretic damping ratio approximately increases linearly with structural response in elasto-plastic stage.

• 대한화학회지
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• 제25권3호
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• pp.152-159
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• 1981

p-니트로벤질클로라이드의 가용매분해 반응속도를 50 와 $60{\circ}C$에서 압력을 1∼1200bar로 변화시키고 에탄올-물 혼합용매의 조성이 0.0∼0.5인 에탄올 몰분율의 범위내에서 전기전도도법으로 측정하였다. 반응의 속도상수로부터 활성화 파라미터, ${\Delta}V_\0^{\neq},\ {\Delta}H^{\neq}$ 및 ${\Delta}S^{\neq}$를 구한결과 ${\Delta}V_\0^{\neq}$는 혼합용매의 몰분율이 0.3부근에서 extremum을 나타내었고 ${\Delta}H^{\neq}$ 와 ${\Delta}S^{\neq}$는 0.1 부근에서 extremum을 나타내었다. 이러한 현상은 용매구조의 변화에 의하여 검토되었고 ${\Delta}V^{\neq}$의 압력의존성도 고찰하였다. ${\Delta}H^{\neq}$와 ${\Delta}S^{\neq}$이 압력의존성은 그 부호에 있어서 고전열역학계에 대한 Maxwell관계의 식과 일치함을 보여주었다.

• 항공우주시스템공학회지
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• 제12권5호
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• pp.32-39
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• 2018

본 논문에서는 소형 압전유압펌프에 적용된 박판 스프링 형 체크밸브의 변형에 의한 이론적인 압력전달 비율을 계산하였다. 박판 체크밸브는 외력에 의해 변형이 발생하는 유연체이며, 체크밸브의 변형은 챔버 압력이 부하 압력으로 전달되는 비율에 영향을 미친다. 박판 체크밸브를 강체로 가정하였을 때와 유연체 모델일 때의 차이를 비교하기 위해 각각의 모델에 대한 이론적인 압력 전달 비율을 계산하였고, 유연체 체크밸브 모델의 압력 전달 비율 계산을 위해 P-delta 효과를 고려하였다. 또한, 유연체 체크밸브 모델의 변형을 고려하여 계산된 압력 전달 비율의 검증 실험을 수행하였다. 실험에는 박판 스프링 형의 체크밸브와 볼-박판 스프링 형의 체크밸브를 각각 적용하여 부하 압력을 측정하였다. 실험을 통해 얻어진 각각의 부하 압력을 이용하여 실험적인 압력 전달 비율을 계산하였다. 실험으로 얻어진 결과를 이론적으로 계산된 압력 전달 비율과 비교하여 P-delta 효과를 고려한 박판형 체크밸브 압력전달 해석의 타당성을 검증하였다.

• 대한치과기공학회지
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• 제23권1호
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• pp.85-93
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• 2001

The purpose of this study was to evaluate the effects of commercial home-tooth bleaching agents on the color of tooth. Twenty five sound extracted teeth were randomly divided into five groups. The color differences between before and after treatment with five types of tooth bleaching agents (7.5% hydrogen peroxide Nite White $Excel^{(R)}$, 10% carbamide peroxide Nite White $Excel^{(R)}$, 16% carbamide peroxide Nite White $Excel^{(R)}$, 10% carbamide peroxide Insta-BriteTM, 20% carbamide peroxide Insta-$Brite^{TM}$) were evaluated. The results were as follows: 1. By 2 week home tooth bleaching agent applications, the values ($L^*$) of bovine teeth increased as high as 4.38 $\sim$ 8.80 when comparing to those of the samples before treatment, and the color difference (${\Delta}E^*$) showed as high as 10.16 $\sim$ 15.04. 2. 16% carbamide peroxide Nite White Excel induced significantly greater ${\Delta}L^*$ than other test edgroups except for 7.5% hydrogen peroxide Day White Excel, and significantly greater ${\Delta}E^*$ than other tested groups by 2 week bleaching agent treatments (p<0.01). 3. 16% carbamide peroxide Nite White Excel(${\Delta}L^*$=8.80, ${\Delta}E^*$=15.04) induced significantly greater ${\Delta}L^*$ and ${\Delta}E^*$ than 10% carbamide peroxide Nite White Excel(${\Delta}L^*$=5.01, ${\Delta}E^*$=10.16)(p<0.01), but significant difference between 10% carbamide peroxide Insta-Brite(${\Delta}L^*$=4.38, ${\Delta}E^*$=10.51) and 20% carbamide peroxide Insta-Brite(${\Delta}L^*$=5.63, ${\Delta}E^*$=11.23) was not shown in ${\Delta}L^*$ and ${\Delta}E^*$(p>0.01). 4. 16% carbamide peroxide Nite White Excel(${\Delta}L^*$=8.80, ${\Delta}E^*$=15.04) which were applied in night time induced significantly greater ${\Delta}L^*$ and ${\Delta}E^*$ than 7.5% hydrogen peroxide Day White Excel(${\Delta}L^*$=8.47, ${\Delta}E^*$=12.75) which were applied in day time. Conclusions: These results demonstrate that all the commercial home-tooth bleaching agents have appreciable bleaching effect on teeth, and the effects of home-tooth bleaching agents which are used during night time are affected by content of carbamide peroxide. Especially the whitening effect of home tooth bleaching agents that are used through night time is greater than that of short time-applying tooth bleaching agent.

• 대한화학회지
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• 제25권1호
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• pp.1-6
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• 1981

o-, m- 및 p-크실렌계와 요오드사이에 형성되는 전하이동착물을 사염화탄소용액에서 자외선분광광도법을 사용하여 연구한 결과$ C_6H_4(CH_3)_2{\cdot}I_2 $형의 1:1 분자착물이 형성됨을 알았다. 이들 착물생성에 대한 흡수최대는 온도가 상승함에 따라 blue shift되므로 이를 고려하여 각 온도에서의 평형정수를 구했다. 이 값으로부터 이들 착물생성에 대한 $ {\Delta}$H, $ {\Delta}$G 및 $ {\Delta}$S의 열역학적 파라미터를 산출하였다. 이 결과와 전 연구결과를 종합하면 폴리메틸벤젠과 요오드와의 착물의 상대적 안정도가 다음 순서로 증가함을 알 수 있었다. Benzene < Toluene < o-Xylene < m-Xylene < p-Xylene 이 결과는 positive inductive effect에 의한 전자밀도증가와 steric hindrance effect에 의한 영향때문인 것으로 설명할 수 있다.

• 멤브레인
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• 제28권5호
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• pp.320-325
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• 2018

FASs (fluoroalkylsilanes)로 표면 개질한 소수성 막에 대한 부탄올/물, 이소프로판올/물 용액의 수착(sorption)량을 측정하였으며 이들 수착 특성을 Hansen 용해도 파라미터를 이용하여 해석하였다. 부탄올의 수착량이 이소프토판올보다 많았으며, 이는 부탄올의 용해도 파라미터(${\delta}_t=20.4$)와 FASs 소수성 막의 용해도 파라미터(${\delta}_t=16.9$)와의 차이가 이소프로판올 (${\delta}_t=24.6$)과의 차이보다 작기 때문인 것으로 설명할 수 있다. 극성력(${\delta}_p$) 측면에서 살펴보면, FASs 극성력(${\delta}_p=4.6$)과 부탄올의 극성력(${\delta}_p=6.3$)과의 차이가 FASs 극성력(${\delta}_p=4.6$)과 이소프로판올의 극성력(${\delta}_p=9.0$)과의 차이보다 작다. 이는 부탄올-FASs 간의 극성력 차이가 이소프로판올-FASs 간의 극성력 차이보다 작아서 부탄올-FASs 간의 상호인력이 크다는 것을 의미하며, 수착량이 크게 나타나는 결과를 설명할 수 있다. 본 실험결과로부터 막에 대한 알코올의 수착특성, 용매에 대한 용질의 용해도 등을 분석하는데 용해도 파라미터를 이용할 수 있음을 알 수 있다.

• Earthquakes and Structures
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• 제8권1호
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• pp.253-273
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• 2015

The current investigation has been conducted to examine the effect of gravity loads on the seismic responses of the doubly asymmetric, three-dimensional structures comprising walls and frames. The proposed model includes the P-${\Delta}$ effects induced by the building weight. Based on the variational approach, a 3D finite element with two nodes and six DOF per node including P-${\Delta}$ effects is formulated. Dynamic and static governing equations are derived for dynamic and buckling analyzes of buildings braced by wall-frame systems. The influences of P-${\Delta}$ effects and height of the building on tip displacements under Hachinohe earthquake record are investigated through many structural examples.

• 대한약침학회지
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• 제21권4호
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• pp.249-257
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• 2018

Objectives: The hepatotoxicity induced by Acetaminophen (AAP) mostly mediated by effect on oxidative stress parameters. The Zataria multiflora (Z.M) is an herbal medicine with well-known antioxidant effect. The aim of this study is investigation of preventive effects of Z.M and Carvacrol (CAR) on AAP-induced hepatotoxicity in rats. Methods: Rats were randomly divided into four groups including: 1) Control, 2) Acetaminophen (AAP), 3) and 4) CAR. The saline, Z.M (200 mg/kg) and CAR (20 mg/kg) were administrated orally for 6 days, after that AAP (600 mg/kg) was administrated in the $7^{th}$ day. Blood sampling was performed on the first and last days. Also, the liver tissue was removed for evaluation of Malondyaldehide (MDA), Thiol content, Superoxide dismutase (SOD) and Catalase (CAT). Total Protein (tPro), Glutamic Oxaloacetic Transaminase (GOT), Glutamic Pyruvic Transaminase (GPT) and Alkaline Phosphatase (ALP) in liver tissue were evaluated. The changes (${\Delta}$) of enzymes activities were presented. Results: The ${\Delta}GOT$, ${\Delta}GPT$ and ${\Delta}ALP$ in CAR group significantly decreased compared to AAP group (P < 0.01 to P < 0.001) and ${\Delta}GPT$ in Z.M group was significantly reduced in comparison with AAP group (P < 0.05). Also, MDA, Thiol, SOD and CAT levels in treated groups were attenuated compared to AAP group (P < 0.05 to P < 0.001). Conclusion: Z.M and CAR have a powerful hepatoprotective effect. CAR is more effective than Z.M. Based on the results. Z.M and CAR could be potent supplementary agents against hepatotoxicity of AAP in patients.