• 대한치과보철학회지
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• 제46권6호
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• pp.553-560
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• 2008

STATEMENT OF PROBLEM: Proximal contact plays an important role in the stability and maintenance of the integrity of the dental arches. However, it is difficult to evaluate quantitatively the tightness of proximal tooth contact (TPTC). PURPOSE: The aim of this study was to measure the TPTC in permanent dentition. MATERIAL AND METHODS: Ten young adult volunteers with healthy dentition participated in this experiment. The TPTC between the teeth of both the maxilla and the mandible was measured at rest state by a novel device which records the TPTC by pulling of a stainless steel strip (0.03 mm thick) using the electric motor. One-way ANOVA test was used to compare the values in all measured area. When a statistically significant difference was calculated, Bonferroni correction was applied. Independent samples t-test was used to compare the values in male and female. RESULTS: The lowest TPTC and the highest TPTC was measured between the lower central incisors (0.87 ${\pm}$ 0.20 N), and between the lower left first molar and second molar (1.99 ${\pm}$ 0.68 N), respectively. All TPTC per quadrant demonstrated a similar pattern of a continuous increased gradient in an anterior-posterior direction. There are no significant difference between the maxilla and mandible. CONCLUSION: The TPTC was measured quantitatively by a novel device and decreased progressively in a posterior-anterior direction.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.439-446
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• 2017

PURPOSE. To evaluate the effects of different surface treatments on the bond strength of novel CAD/CAM restorative materials to resin cement by four point bending test. MATERIALS AND METHODS. The CAD/CAM materials under investigation were e.max CAD, Mark II, Lava Ultimate, and Enamic. A total of 400 bar specimens ($4{\times}1.2{\times}12mm$) (n=10) milled from the CAD/CAM blocks underwent various pretreatments (no pretreatment (C), hydrofluoric acid (A), hydrofluoric acid + universal adhesive (Scotchbond) (AS), sandblasting (Sb), and sandblasting + universal adhesive (SbS)). The bars were luted end-to-end on the prepared surfaces with a dual curing adhesive resin cement (Variolink N, Ivoclar Vivadent) on the custom-made stainless steel mold. Ten test specimens for each treatment and material combination were performed with four point bending test method. Data were analyzed using ANOVA and Tukey's test. RESULTS. The surface treatment and type of CAD/CAM restorative material showed a significant effect on the four point bending strength (FPBS) (P<.001). For LDC, AS surface treatment showed the highest FPBS results ($100.31{\pm}10.7MPa$) and the lowest values were obtained in RNC ($23.63{\pm}9.0MPa$) for control group. SEM analyses showed that the surface topography of CAD/CAM restorative materials was modified after treatments. CONCLUSION. The surface treatment of sandblasting or HF acid etching in combination with a universal adhesive containing MDP can be suggested for the adhesive cementation of the novel CAD/CAM restorative materials.

• 대한치과보철학회지
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• 제45권3호
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• pp.295-302
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• 2007

Statement of problem. Fracture of the tooth-colored superstructure material is one of the main prosthetic complications in implant-supported prostheses. Purpose. The purpose of this in vitro study was to compare the fracture strength between the cement-retained implant-supported metal-ceramic crowns and the indirect composite resinveneered metal crowns under the vertical compressive load. Material and methods. Standard implants of external type (AVANA IFR 415 Pre-mount; Osstem Co., Busan, Korea) were embedded in stainless steel blocks perpendicular to their long axis. Customized abutments were fabricated using plastic UCLA abutments (Esthetic plastic cylinder; Osstem Co., Busan, Korea). Thirty standardized copings were cast with non-precious metal (Rexillium III, Pentron, Walling ford, Conn., USA). Copings were divided into two groups of 15 specimens each (n = 15). For Group I specimens, metal-ceramic crowns were fabricated. For Group II specimens, composite resin-veneered (Sinfony, 3M-ESPE, St. Paul, MN, USA) metal crowns (Sinfony-veneered crowns) were fabricated according to manufacturer's instructions. All crowns were temporary cemented and vertically loaded with an Instron universal testing machine (Instron 3366, Instron Corp., Norwood, MA, USA). The maximum load value (N) at the moment of complete failure was recorded and all data were statistically analyzed by independent sample t-test at the significance level of 0.05. The modes of failure were also investigated with visual analysis. Results. The fracture strength of Sinfony-veneered crowns ($2292.7{\pm}576.0N$) was significantly greater than that of metal-ceramic crowns ($1150.6{\pm}268.2N$) (P < 0.05). With regard to the failure mode, Sinfony-veneered crowns exhibited adhesive failure, while metal-ceramic crowns tended to fracture in a manner that resulted in combined failure. Conclusion. Sinfony-veneered crowns demonstrated a significantly higher fracture strength than that of metal-ceramic crowns in cement-retained implant-supported prostheses.

• 콘크리트학회논문집
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• 제16권1호
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• pp.43-53
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• 2004

철근콘크리트 부재가 취성적이며 국부적으로 파괴되지 않도록 하기 위하여 각 기준식에서는 철근콘크리트 부재의 최소전단 보강근비를 요구하고 있다. 우리나라에서 현재 사용되고 있는 철근콘크리트 구조설계기준의 최소전단철근비에 대한 기준식과 캐나다 기준식, 유럽 기준식, 일본건축학회 기준식을 비교하면 각 기준식에 의하여 계산된 최소전단보강근비 값에는 많은 차이가 있어 그 신뢰성에 의문을 갖게 한다. 즉, 동일한 콘크리트의 실린더 압축강도에 대하여 각 기준식의 최소전단보강근비 값은 최대 2배 이상의 차이가 있다. 또한, 최소전단보강근비에 영향을 주는 요소가 각 기준식마다 다르며, 이에 대한 연구도 그 중요성에 비하여 극히 적은 실정이다. 이연구에서는 트러스 모델에 근거한 이론적인 방법에 의하여 철근콘크리트 부재의 최소전단보강근비를 예측하였다. 제안식에는 최소전단철근비에 영향을 주는 콘크리트의 압축강도, 전단보강근의 항복응력, 주근비, 전단경간비의 영향이 고려되었다. 제안식에 의하여 계산된 최소전단철근비는 콘크리트 압축강도에 따라 변화하며, ACI 318-02 및 캐나다 규준과 비슷한 분포를 나타냈다. KCI-99 및 ACI 318-02의 최소전단철근비는 주인장철근비에 관계없이 일정하지만 제안식에 의한 최소전단철근비는 주인장철근비가 증가할수록 줄어드는 양상을 보였다. 또한, 전단경간비에 따른 최소전단철근비에 대하여 KCI-99 및 ACI-318-02에 의한 최소전단철근비는 전단경간비에 관계없이 일정한 값을 보였지만 제안식에 의한 최소전단철근비는 전단경간비가 증가할수록 증가하는 양상을 보였다.변화로 인한 resetup의 번거러움을 줄일 수 있었고 환자에게 인위적으로 치료 자세를 유지해야하는 불편함을 해소할 수 있었다. 궁극적으로는 set-up의 재현성을 유지해 보다 정확한 치료를 가능하게 했고 앞으로 이 고정용구를 보완, 개선시켜서 환자의 치료에 활용한다면 더욱더 질적으로 향상된 치료를 제공 할 수 있을 것으로 사료된다.하였다. IV. 결론 Forward IMRT는 2차원적인 치료법에 비하여 PTV에는 균일한 선량분포를 이루면서 정상조직에는 tolerance dose 이하로 선량을 전달 할 수 있는 치료기법이었다. 계속적으로 평가할 필요가 있을 것이다.> 최대 $11.65\%$까지 골조직에 의한 선량감소가 나타나는 것을 알 수가 있다. 또한, Diode detector로 측정한 심부선량 값은 두부, 경부, 대퇴부, 슬관절, 족관절에서 각각 $95.23{\pm}1.18,\;98.33{\pm}0.6,\;93.5{\pm}1.5,\;87.3{\pm}1.5,\;86.90{\pm}1.16$으로 나타났으며, TLD로 측정한 대퇴부, 슬관절, 족관절에서의 표면선량과 비교했을 때 부위에 따라 최소 $4.53\%{\sim}$ 최대 $12.6\%$ 까지 차이를 보였다. 그리고 골조직에 의한 선량감쇄의 영향이 적은 복부(배꼽)에서는 열형광선량계 및 다이로드측정기로 측정한 값이 각각 $101.58{\pm}0.95,\;104.77{\pm}1.18$로 큰 차이가 없었다. IV 결론 전신방사선조사시 표면선량을

• 한국수소및신에너지학회논문집
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• 제24권1호
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• pp.44-49
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• 2013

Hydrogen penetration into a metal leads to damages and mechanical degradations and its content measurement is of importance. For a precise measurement, a sample preparation procedure must be optimized through a series of studies on sample washing and drying. In this study, two-step washing with organic solvents and thermal soaking in inert gas were tried with a rod-shaped, API X65 steel sample. The samples were machined from a steel plate and then washed in acetone and etyl-alcohol for 5 minute each and dried with compressed air. After then, the samples were thermally soaked in a home-made nitrogen gas chamber during 10 minute at different heat gun temperatures from 100 to $400^{\circ}C$ and corresponding temperature range in the soaking chamber was from 77 to $266^{\circ}C$ according to the temperature calibration. Hydrogen residue in the samples was measured with a hot extraction system after each soaking step; hydrogen residue of $0.70{\pm}0.12$ wppm after the thermal soaking at $77^{\circ}C$ decayed with increase of the soaking temperature. By adopting the heat transfer model, decay behavior of the hydrogen residue was fitted into an exponential decay function of the soaking temperature. Saturated value or lower bound of the hydrogen residue was 0.36 wppm and chamber temperature required to lower the hydrogen residue about 95% of the lower bound was $360^{\circ}C$. Furthermore, a thermal desorption spectroscopy was done for the fully soaked samples at $360^{\circ}C$. Weak hydrogen peak was observed for whole temperature range and it means that hydrogen-related contaminants of the sample surface are steadily removed by heating. In addition, a broad peak found around $400^{\circ}C$ means that parts of the hydrogen residue are irreversibly trapped in the steel microstructure.

• 한국식품과학회지
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• 제49권4호
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• pp.369-376
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• 2017

전통 쌀 증류식 소주를 제조하여 오크통에 숙성시킴으로써 숙성 중에 증류주의 이화학적 특성 및 향기성분의 변화를 측정하였다. 입국(Aspergillus luchuensis)과 선발된 효모(Saccharomyces cerevisiae Y88-4)로 담금한 발효주를 감압 증류하였다. 제조된 증류주는 오크통과 스테인리스통에 12개월 간 실온 숙성 하였다. 숙성 12개월 후 숙성 전에 비해 MSO (Maturated distilled spirits in Oak)와 MSS (Maturated distilled spirits in stainless) 모두 알코올과 pH가 감소하였고, 산도, 전기전도도는 증가하는 경향을 나타냈다. 손실량, 탁도와 적색도, 황색도, 퓨젤유에서 MSO는 유의적으로 증가하였으나, MSS는 변화가 없었다. 향기성분은 ester 류 20종, alcohol 류 7종, acids 류 2종, 기타 5종으로 총 34종의 향기성분이 검출되었다. 12개월 숙성 후 아세트산 에틸, 페닐에틸 알코올이 감소하였고, 카푸릴산 에틸은 증가하여 향기성분에 변화를 나타냈다. 특히 oaklacton과 푸르푸랄은 MSO에서만 검출되어 오크 숙성시 발생하는 특징적인 향기성분으로 사료된다. 전통 쌀 증류주의 오크통 숙성은 알코올 및 손실량은 컸으나, 오크통의 다양한 물질과 반응하면서 색도 및 향기성분이 유의적인 차이를 나타냈다. 이로써 숙성 용기의 선택이 숙성 증류주의 품질에 영향을 미치는 것으로 사료되며, 숙성과정을 통해 다양하고 특색있는 주류제조가 가능할 것으로 기대된다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.172-177
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• 2004

This paper presents the results of the structural analysis and optimal design of frames of the UUV(Unmanned Underwater vehicle) to be operated at 6000m depth in the ocean. The structure of the UUV system can be classified into two structure, Launcher ana ROV. Frame of the launcher will be made by Galvanized Steel which has high strength and corrosion-resistant but this material has high specific gravity for tile object to be weight in the water Similarly, ROV will be made by AI6061-T6, and frame of the ROV will be fix many instruments and syntactic buoyancy materials. Before fabrication of tile frame, we performed sensitivity analysis - change in weight due to $\pm1\%$ change in design variables, for easy choice by change of dimension of the frame.

• Journal of Acupuncture Research
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• 제29권6호
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• pp.1-10
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• 2012

Objectives : The aim of this review was to summarize and assess researches reporting thermal properties of moxibustion. Methods and Materials : We searched one electronic database(PubMed) and two journals(The Journal of Korean Medicine and The Journal of Korean Acupuncture & Moxibustion Society) and for the articles published until Nov. 2012. The articles reporting thermal characteristic of moxibustion were selected and reviewed. 31 articles were included and assessed in this review. The type of moxibustion, the material beneath moxbustion, main outcome and the amount of information were reviewed. The amount of information was defined as 1 for one main outcome reported in each article. Results : Direct moxibustion were used in 15 articles and indirect moxibustion were used in 19 articles. 11 researches used anti-heating plate for the material beneath moxibustion, one article used steel ring, agar with anti-heating plate, six articles used skin and another six articles used heater. Two articles used animals and another two articles used metals. The mean value of the amount of information was $4.41{\pm}2.94$(SD). Conclusions : Research articles assessing properties of moxibustion have been consistently published since 1993, and employed various methodologies. The amount of information has been associated with four section analysis and is currently decreasing. Research assessing properties of moxibustion with clinical effectiveness is needed.

• Wind and Structures
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• 제10권6호
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• pp.555-576
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• 2007

Statistical analysis on the measured responses of a suspension bridge deck (Law, et al. 2007) show that vibration response at the first torsional mode of the structure has a significant increase at and beyond the critical wind speed for vortex shedding as noted in the wind tunnel tests on a sectional model. This paper further analyzes the measured responses of the structure when under typhoon conditions for any possible vortex shedding events. Parameters related to the lifting force in such a possible event and the vibration amplitudes are estimated with a single-degree-of-freedom model of the system. The spatial correlation of vortex shedding along the bridge span is also investigated. Possible vortex shedding events are found at both the first torsional and second vertical modes with the root-mean-square amplitudes comparable to those predicted from wind tunnel tests. Small negative stiffness due to wind effects is observed in isolated events that last for a short duration, but the aerodynamic damping exhibits either positive or negative values when the vertical angle of wind incidence is beyond ${\pm}10^{\circ}$. Vibration of the bridge deck is highly correlated in the events at least in the middle one-third of the main span.

• Steel and Composite Structures
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• 제24권2호
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• pp.151-176
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• 2017

This paper deals with general equations of motion for free vibration analysis response of thick three-layer doubly curved sandwich panels (DCSP) under simply supported boundary conditions (BCs) using higher order shear deformation theory. In this model, the face sheets are orthotropic laminated composite that follow the first order shear deformation theory (FSDT) based on Rissners-Mindlin (RM) kinematics field. The core is made of orthotropic material and its in-plane transverse displacements are modeled using the third order of the Taylor's series extension. It provides the potentiality for considering both compressible and incompressible cores. To find these equations and boundary conditions, Hamilton's principle is used. Also, the effect of trapezoidal shape factor for cross-section of curved panel element ($1{\pm}z/R$) is considered. The natural frequency parameters of DCSP are obtained using Galerkin Method. Convergence studies are performed with the appropriate formulas in general form for three-layer sandwich plate, cylindrical and spherical shells (both deep and shallow). The influences of core stiffness, ratio of core to face sheets thickness and radii of curvatures are investigated. Finally, for the first time, an optimum range for the core to face sheet stiffness ratio by considering the existence of in-plane stress which significantly affects the natural frequencies of DCSP are presented.