• 한국수산과학회지
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• 제40권3호
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• pp.117-121
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• 2007

To optimize the mixing ratio of ingredients to obtain the best sensory qualities, a response surface methodology with a central composite design was performed on hot water extracts using crucian carp Carassius carassius treated with diluted vinegar (pH 5.24-5.30). The optimal solutions for four parameters (overall acceptability, odor, flavor, and taste) were obtained using the second-order response surface regression models. The optimal formulation appeared to be 124.15 g of ginger and 96.09 g of garlic with 1 kg of ground crucian carp meat based on the desirability function technique.

• Steel and Composite Structures
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• 제33권6호
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• pp.767-776
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• 2019

In this article, a simple and robust multi-objective assessment method to control design angles and node positions connected among steel outrigger truss members is proposed to approve both structural safety and economical cost. For given outrigger member layouts, the present method utilizes general-purpose prototypes of outrigger members, having resistance to withstand lateral load effects directly applied to tall buildings, which conform to variable connecting node and design space deposition. Outrigger layouts are set into several initial design conditions of height to width of an arbitrary given design space, i.e., variable design space. And then they are assessed in terms of a proposed multi-objective function optimizing both minimal total displacement and material quantity subjected to design impact factor indicating the importance of objectives. To evaluate the proposed multi-objective function, an analysis model uses a modified Maxwell-Mohr method, and an optimization model is defined by a ground structure assuming arbitrary discrete straight members. It provides a new robust assessment model from a local design point of view, as it may produce specific optimal prototypes of outrigger layouts corresponding to arbitrary height and width ratio of design space. Numerical examples verify the validity and robustness of the present assessment method for controlling prototypes of outrigger truss members considering a multi-objective optimization achieving structural safety and material cost.

• Journal of the Korean Wood Science and Technology
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• 제43권5호
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• pp.672-681
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• 2015

As a part of abating the formaldehyde emission of amino resin-bonded wood-based composite panels, this study was conducted to investigate hydrolytic stability of urea-melamine-formaldehyde (UMF) resin depending on various hydrolysis conditions and hardener types. Commercial UMF resin was cured and ground into a powdered form, and then hydrolyzed with hydrochloric acid. After the acid hydrolysis, the concentration of liberated formaldehyde in the hydrolyzed solution and mass loss of the cured UMF resins were determined to compare their hydrolytic stability. The hydrolysis of cured UMF resin increased with an increase in the acid concentration, time, and temperature and with a decrease in the smaller particle size. An optimum hydrolysis condition for the cured UMF resins was determined as $50^{\circ}C$, 90 minutes, 1.0 M hydrochloric acid and $250{\mu}m$ particle size. Hydrolysis of the UMF resin cured with different hardener types showed different degrees of the hydrolytic stability of cured UMF resins with a descending order of aluminum sulfate, ammonium chloride, and ammonium sulfate. The hydrolytic stability also decreased as the addition level of ammonium chloride increased. These results indicated that hardener types and level also had an impact on the hydrolytic stability of cured UMF resins.

• 대한치과기공학회지
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• 제25권1호
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• pp.21-28
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• 2003

The purpose of this study was to process bio-active glass ceramic composite, reinforced with sapphire fibers, by hot press. Also to study the interface of the matrix and the sapphire fiber, and the mechanical properties. Glass raw materials melted in Pt crucible at 1300$^{\circ}C$ during 3.5 hours. The melt was crushed in ball mill and then crushed material, ground and sieved to $<40{\beta}{\mu}m$. Sapphire fibers cut (30mm) and aligned. Powder and fibers hot pressed. The micrographs show good bonding between the matrix and the fiber and no porosity in the glass matrix. This means ideal fracture phenomena. Glass is fractured before the fiber. This is indication of good fracture strength. EDXS showing aluminum rich phase and crystalline phase. Bright field image of the matrix showing crystalline phase. Also diffraction pattern of TEM showing the crystalline phase and more than one phase. Strength of the samples was determined by 3 point bend testing. Strength of the 10vol% sample was approximately 69MPa, while strength of the control sample is 35MPa. Conclusions through this study as follow: 1. Micrographs show no porosity in the glass matrix and the interface. 2. The interface between the fiber and the glass matrix show no gaps. 3. Fracture of the glass indicates characteristic fiber-matrix separation. 4. Presence of crystalline phase at high processing temperature. 5. Sapphire is compatible with bioactive glass.

• 대한치과기공학회지
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• 제29권2호
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• pp.141-150
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• 2007

The purpose of this study was to ascertain the bonding durability of self-etching dentin bonding agents to dentin by means of shear bonding strength. Several acid-etching dentin bonding system (ESPE Z100) and self-etching dentin bonding systems (DEN-FIL, GRADIA DIRET) were used. The occlusion surface of human molars were ground flat to expose dentin and treated with the etch bonding system according to manufactures instruction and followed by composite resin application. After 24hours of storage at 37$^{\circ}C$, the shear bonding strength of the specimens was measured in a universal testing machine with a 1mm/min crosshead speed. An one-way analysis of variance and the scheffe test were performed to identify significant differences (p<0.05). The bonded interfacial surfaces and treated dentin surfaces were examined using a SEM. Through the analysis of shear bond strength data and micro-structures of dentin-resin interfaces, following results are obtained. In dentin group, the shear bond strength of DEN-FIL showed statistical superiority in comparison to the other groups and followed by ESPE Z100 and GRADIA DIRECT (p<0.05).

• 한국지반공학회논문집
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• 제19권4호
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• pp.75-81
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• 2003

초연약 고소성의 준설해성점토를 보강하기 위하여 Micro-Fiber(MF)재를 혼합하여 다양한 실내시험을 수행하였다. 준설점토의 함수비를 3종으로 조정하고 각각의 시료에 MF를 길이와 혼합율을 변화시키면서 일축압축 및 삼축압축 시험을 통하여 보강특성을 검토하였다. 또한, 양생일수벽로 강도증가 경향을 평가하였으며, 폐석회(Waste Lime, WL)의 추가혼합이 보강기능을 증대시키는지 여부를 검토하였다. 실험결과, MF를 혼합함에 따라 준설점토의 강도가 자연함수비에 무관하게 약 50% 증가하였으며, MF의 길이가 길수록 보강효과가 크게 나타났다. 또한, 합리적인 MF의 혼합율은 2% 정도이며, 추가적으로 폐석회를 약 10% 혼합할 경우 중장비주행이 가능한 보강효과가 나타나는 것을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.862-867
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• 2014

When the vehicle is traveling, the deformation caused by friction continued with the ground is made to occur because the tire is the composite material of a viscoelastic. Part of the deformation energy is converted into heat energy as Hysteresis and temperature inside the tire rises. The generated heat is shed to the outside through the convection and evangelism. Increase in the internal temperature of the tire is difficult to ensure the safety of vehicle by damage to the tire during driving. Recently, Even when the tire is damaged, it is designed to be possible to driving in case of run-flat tires but the fact is that the development of the technology for the synergistic effect of heat release inside the tire by the side reinforcement is necessary. In this study, by using the Finite Element Method (FEM), applying the cooling fins to the tire sidewall, it is intended to check the temperature distribution along the shape of the cooling fins and the temperature reduction effect.

• Steel and Composite Structures
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• 제1권1호
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• pp.145-158
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• 2001

An experimental study was conducted to evaluate the effects of loading sequence and lateral bracing on the behavior of reduced beam section (RBS) steel moment frame connections. Four full-scale moment connections were cyclically tested-two with a standard loading history and the other two with a near-fault loading history. All specimens reached at least 0.03 radian of plastic rotation without brittle fracture of the beam flange groove welds. Two specimens tested with the nearfault loading protocol reached at least 0.05 radian of plastic rotation, and both experienced smaller buckling amplitudes at comparable drift levels. Energy dissipation capacities were insensitive to the types of loading protocol used. Adding a lateral bracing near the RBS region produced a higher plastic rotation; the strength degradation and buckling amplitude were reduced. A non-linear finite element analysis of a one-and-a-half-bay beam-column subassembly was also conducted to study the system restraint effect. The study showed that the axial restraint of the beam could significantly reduce the strength degradation and buckling amplitude at higher deformation levels.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.664-667
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• 2010

고체 추진기관은 다른 추진기관에 비해 구조가 간단하고 운용성이 좋아 전략무기의 추진기관으로 주로 사용되고 있다. 그러나 고체 추진기관의 추력형상은 추진제의 연소속도와 추진제 그레인의 연소면적에 의해 결정되며, 추진제의 외경, 길이, 무게, 충전율 등과 같은 다른 설계요소들에 의해 요구되는 추력형상의 획득에 제약을 받는다. 고체 추진기관의 이중추력 성능은 일반적으로 사거리 연장과 종말 속도 향상에 장점이 있으나 추진제 그레인의 형상만으로 성능을 획득하고자하는 경우 연소관 내 추진제의 충전율이 저하된다. 따라서 연소속도가 다른 이종추진제를 적용하여 이중추력을 획득하는 것이 유리하다. 본 연구에서는 연소속도가 다른 이종 추진제를 적용하여 소형 고체 추진기관의 내외탄도 해석 및 지상연소시험을 통해 이중추력 성능을 확인함으로써 이중추력 추진기관 개발 가능성을 확인하였다.

• Steel and Composite Structures
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• 제22권3호
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• pp.589-611
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• 2016

The primary objectives of this research are to investigate the energy factor response of steel moment resisting frame (MRF) systems equipped with fuses subject to ground motions and to develop an energy-based evaluation approach for evaluating the damage-control behavior of the system. First, the energy factor of steel MRF systems with fuses below the resilience threshold is derived utilizing the energy balance equation considering bilinear oscillators with significant post-yielding stiffness ratio, and the effect of structural nonlinearity on the energy factor is investigated by conducting a parametric study covering a wide range of parameters. A practical transformation approach is also proposed to associate the energy factor of steel MRF systems with fuses with classic design spectra based on elasto-plastic systems. Then, the energy balance is extended to structural systems, and an energy-based procedure for damage-control evaluation is proposed and a damage-control index is also derived. The approach is then applied to two types of steel MRF systems with fuses to explore the applicability for quantifying the damage-control behavior. The rationality of the proposed approach and the accuracy for identifying the damage-control behavior are demonstrated by nonlinear static analyses and incremental dynamic analyses utilizing prototype structures.