• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.416-419
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• 1995

An analysis of a new load resonant inverter considering stray inductance is given. There are several different types for load resonant inverters. They can offer zero turn-on as well as zero turn-off switching losses, yielding high efficiency at high power and high frequencies. However, they didn't consider the influences of stray inductance. In conventional topology using lossless snubber capacitor, stray inductances result in very high frequency resonant current. Especially, these influences can be problematic in high power system such as induction heating system with large current of some 10A associated with it. These currents increase EMI problem, give harmful effects in gate driver's operation and increase loss of dc-link capacitor as well as snubber capacitor. Therefore, the effect of stray inductances should be treated and reduced. This paper presents a new load resonant inverter topology, which can reduce the effect of stray inductances.

• Korean Journal of Agricultural Science
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• v.37 no.2
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• pp.271-276
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• 2010

In this study, the light-frame wood shear walls according to the sheathing materials was carried out to investigate the shear load performance. Most common sheathing materials are the structural OSB and gypsum board used to consist wall of wood-frame house. Seven different type of specimens are composed of several sheathing materials and shear test was taken to evaluate shear performance by KS F 2154. As a result, shear walls(G12.5/G12.5 and G12.5/OSB) show that maximum shear strength and shear rigidity modulus are 7316N/mm${\cdot}$118.25 N/mm and 11129 N/mm${\cdot}$184.66 N/mm respectively. The shear wall using gypsum board 15mm improve maximum shear strength and shear rigidity modulus about 30%. The shear wall using 15mm gypsum board showed intermediate value in one side specimens. Different types of shear walls could be compared with the shear load performance. Also, nailed joint failure aspects are different to sheathing material and installing method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.04a
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• pp.126-133
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• 1992

The structural soundness of bridges is mainly damaged by overloaded heavy vehicles. The increasing volumes of overloaded heavy vehicles has been indicated as serious state. As results several countries have revised their bridge load codes. However, because of variety of truck types and their weights it is difficult to develop rational standard truck loads. In addition the common practice that only one design configuration of standard truck is adopted to design variety of bridges causes further difficulties. The objective of the study is to investigate the statistical characteristics of vehicle loadings based on survey data col looted, in which some major factors, such as vehicle configurations, vehicle freights, traffic modes, etc. are incorporated.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.32-41
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• 2003

For the countermeasure of expected higher thermal load in miller cycle engine, coolant flows in the cylinder head of base engine with several coolant flow methods and drilled hole passages were measured by using PIV technique. And the cooling effect was evaluated by measurements of wall temperatures according to each coolant flow method. It was found that the series flow system was most suitable among the discussed 3 types of coolant flow methods since it had the best cooling effect in cylinder head by the fastest coolant flow velocity It was also found that for drilled water passage to decrease the large thermal load in exhaust valve bridge, nozzle type is more effective compared with round type of water passage, and its size has to be determined according to the coolant flow pattern and velocity in each cylinder.

• Journal of KSNVE
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• v.8 no.6
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• pp.1150-1157
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• 1998

In this Paper, we present an efficient method for finite element vibration analysis of constantly rotating structures with cyclic symmetry, which are deformed to some considerable extent by centrifugal force, Coriolis force and operating load, and vibrate due to several types of exciting forces. A structure with cyclic symmetry is composed of circumferentially repeated substructures with the same geometry. Being only one substructure modeled. the dynamic characteristics of the structure can be analyzed systematically. rapidly and exactly using discrete Fourier transform by means of a computer with small memory.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1279-1286
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• 2010

This paper deals with the influence on the dynamic response of I-type girder railway bridge with high-speed electric multiple unit(HEMU) train load. This bridge system which has six I-girder and several cross beams, is modeled with plate and frame elements. And the upper slab is assumed to be fully connected with girders using rigid rinks. Span lengths, types of vehicle and running speeds are selected as parameters for analyses. For more exact analysis, it was adopted that 3-dimensional section of bridge models was produced by the assumed design wheel loads of HEMU vehicle at 200~350 km/hr speeds. Dynamic vertical deflections, dynamic amplification factors and vertical accelerations of bridges having 30 and 35 m span length were investigated and compared with the limit values specified in various national railway bridge specifications.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.1
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• pp.55-62
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• 2002

In this paper, several types of infiltration prevention devices that are currently in use have been studied through experimental investigation. Firstly, the types of infiltration prevention devices were defined through investigating actual conditions of refrigerated warehouse in operates. Based on this investigation results, measured change of temperature and figured out air change rates of the type of infiltration prevention devices by using scale down model. After that, found the amount of air change rate in order to estimate the load of air change easily in facility plan.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1541-1547
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• 2006

An efficient procedure to obtain the optimal stacking sequence and the minimum weight of stiffened laminated composite curved panels under several loading conditions and stiffener layouts has been developed based on the finite element method and the genetic algorithm that is powerful for the problem with integer variables. Often, designing composite laminates ends up with a stacking sequence optimization that may be formulated as an integer programming problem. This procedure is applied for a problem to find the stacking sequence having a maximum critical buckling load factor and the minimum weight. The object function in this case is the weight of a stiffened laminated composite shell. Three different types of stiffener layouts with different loading conditions are investigated to see how these parameters influence on the stacking sequence optimization of the panel and the stiffeners. It is noticed from the results that the optimal stacking sequence and lay-up angles vary depending on the types. of loading and stiffener spacing.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.3
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• pp.470-485
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• 1997

A fundamental principle in clasp selection for a specific abutment is the reduction of the transmission of excessive forces to the abutment tooth. Those forces include tilting, tipping, and stress on the abutment tooth. The flexibility of a clasp was believed to directly affect the reduction of such forces. Opinions have been expressed concerning the proper type of clasp to be used to prevent stress on periodontium. In order to evaluate and compare the various designs of a clasp system, it is necessary to measure these forces. This study compared the average measurements of forces required to dislodge three kinds of circumferential clasps having different amount of undercuts : the first with a round retentive arm, the second with a half round retentive arm, the third with a wrought wire retentive arm under tensile load. Three commonly used undercuts( 0.01, 0.02, 0.03 inch) were created on nine cast crowns, premolars and molars. The test was run six times for a same clasp. The means of tensile load required to dislodge each of the different clasps were compared statistically using the ANOVA test and multiple range test (Duncan test). The results were as follows. 1. The amount of tensile load of the wrought wire clasp was significantly different from the cast round or half round clasp (p<0.05). 2. The more amount of the undercut, the more tensile load was needed to dislodge the clasps. There were significant differences among them (p<0.05). 3. The molar showed higher tensile load than the premolar, and there was significant difference (p<0.05). 4. The means of tensile load according to clasp types showed significant differences at the molar between wrought wire clasp and cast clasp (p<0.05), but did not at the premolar.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.8-15
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• 2018

Hollow Core Slab is a very efficient system that can reduce weight and its use has increased. Void slab is a concrete slab that has voids substituted with void material. Because of its saved volume of concrete, void slab can reduce weight of slabs. Also, it can't only save concrete but also can reduce carbon-emission. However, because of the unclear bearing strength at the part of void substituted with voiding material, several problems occur in constructing field. In this study, void slab including void material was built and local bearing strength test was carried out for 3 types of load(truck load, support load and Jack support load). As a result, bearing strength of void neck and upper void material is more than allowable load. And also, bearing strength of specimens with using deck and not using deck are also over allowable loads.