• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.950-953
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• 2005

Floor impact sounds from two different floor systems were measured. One of the two floor systems is a dry floor system (with 150mm concrete slab) and the other is a standard floor system (210mm concrete slab). Real impact sources such as jumping and running of children were used as well as standard impact sources (bang machine, impact ball and tapping machine) to evaluate sound Isolation of the two floor systems. Subjective evaluations of the floor impact sound isolation performance for the two systems were also conducted by the methods of 3 scales & 9 categories, paired comparison and semantic differentials. Measurement results indicate that floor impact sound isolation performance of the dry floor was better than that of standard floor in both cases of real and standard impact sources. The subjects in auditory experiments also evaluated the dry floor as a better sound isolation system.

• Journal of KSNVE
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• v.8 no.3
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• pp.513-523
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• 1998

Impact response of a vibro-impact system and its contact mechanism was studied. The vibro-impact system is composed of a small secondary system is constrained to move along a slot of fixed length in a large primary system. The contact mechanism is characterized by its coefficient of restitution. Numerical simulation analysis has been used to determine the time-history and the impact statistics of the primary and secondary systems. Input excitation of the primary system was random, and the responses obtained were the velocities of the primary and secondary system, the closing velocity in time axis and the duration time between impacts. The validity of the numerical simulation method was checked by comparing the results with those obtained by other researchers analytically. It is shown that the results obtained by the nemerical simulation analysis showed a good agreement with those for the analytical method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.689-689
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• 2010

Since the apartment was built by Korea National Housing Cooperation in 1961, the amount of its supply has been increased greatly, especially from the late 70's. Recently there are many ongoing studies regarding sustainable construction apartment in Korea, one of the research is developing sustainable apartment that has longer life cycle. Also according as life's quality of residents is upgrading, complain for impact noise and plumbing system noise from upstair or downstair are increasing more and more. To solve this complains, government established impact noise standard as lightweight impact noise of 58dB, heavyweight impact noise of 50dB and presented standard floor system or recognition floor system to satisfy this impact noise standard. So in this study, the aim is to develop dry ondol access floor system for sustainable apartment which have pleasant and quiet life environment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.197-202
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• 2014

Floor Impact Noise is a structure-borne noise which is mainly caused by vibration of concrete slabs. The majority of previous studies have focused on investigating performance of absorbing sheets on the reduction of floor impact noise. But absorbing sheets do not efficiently reduce heavy-weight floor impact noise level because it cannot absorb slab vibration, which is the fundamental noise source. In this study, double-floor system was developed in order to reduce floor impact noise level in residual buildings. This floor system reduces heavy-weight impact noise level by reducing vibration response at the center of slab, which has maximum amplitude in the 1st vibration mode. In order to identify the performance of the double-floor system, experiments were planned. Primary test parameters are span of double floor, arrangement and types of absorbing sheets.

• Korean Journal of Computational Design and Engineering
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• v.7 no.1
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• pp.27-33
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• 2002

MDO(Multidisciplinary Design Optimization) methodology is a new technology to solve a complicate design problem with a large number of design variables and constraints. The design of a dental implant system is a typical complicate problem, and so it requires the MDO methodology. Actually, several analyses such as rigid body dynamic analysis and structural stress analysis etc. should be carried out in the MDO methodology application to the design of a dental implant system. In this paper, as a first step of MDO methodology application to the design of a dental implant system, the impact force which is applied on the tooth in masticating is calculated through the rigid body dynamic analysis of upper and lower jaw-bones. This analysis is done using ADAMS. The impact force calculated through the rigid body dynamic analysis can be used for the structural stress analysis of a dental implant system which is needed for the design of a dental implant system. In addition, the rigid body dynamic analysis results also show that the impact time decreases as the impact force increases, the largest impact force occurs on the front tooth, and the impact force is almost normal to the tooth surface with a slight tangential force.

• 연구논문집
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• s.32
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• pp.45-53
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• 2002

Hydraulic breaker attached excavator generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and etc. The developed breaker are determined their own destructive force and number of impact by the input hydraulic flow rate and pressure than the operating conditions, In this study, the characteristics of pressure variation in closed vessel is invested for testing the impact energy of hydraulic breaker. To test the impact energy, the test system is designed as a mechanism consisted with a hydraulic cylinder, main base, pressure sensor, LVDT, data acquisition system and etc.. The developed test system is applied to measure the impact energy for hydraulic breaker. The proposed testing method could be applied for conventional impact test and the control system evaluation for hydraulic breakers.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.8-23
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• 2008

The purpose of this study is to develop a Cross Impact System Alternatives Tree(CISAT) model necessary for selecting the interdependent R&D planning system alternatives. This model modifies System Alternatives Tree(SAT) model developed by Kwon et al.. The SAT model is composed of several functions necessary for the achievement of a final goal and several subsystems for satisfying each function. In case that the relationship of technology alternatives is interdependent, this model overlooked a relative importance derived from occurrence or nonoccurrence of the technology alternatives in the future time varience. However, a complex evaluation process within the ballot system is another disadvantage of the SAT. To solve such problems, the Cross Impact Analysis(CIA) model is applied in the SAT model so as to consider the cross impact among interdependent system alternatives.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1529-1532
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• 2003

This paper deals with the impact analysis of the impact absorbing system consist of one degree of freedom and two degree of freedom damping-spring system in spreader to increase efficiency of it. It shows the optimum damping coefficient and spring constant of impact absorbing system using for crane spreader and the optimum condition of impact absorbing system causing certain contact impulse. In the optimal model, the contact impulse is reduced 98.57 percent and 92.22 percent respectively.

• KIEAE Journal
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• v.14 no.1
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• pp.39-48
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• 2014

In the previous test, the verification of the standard floor impact source was carried out comparing the physical characteristics with living impact sources. The result was appeared the validation of the standard impact source was very low because of differences of physical characteristics. This study aims to evaluate annoyance and loudness of standard impact source which is used for the measurement of floor impact sound, and to compare the annoyance and loudness of living impact sources which are produced in real life. The impact sources considered are tapping machine, tire and impact ball as standard sources, and nine real sources which were chosen from the existing researches. The result showed differences of annoyance and loudness between standard impact sources and living impact sources, which means the standard impact sources may rate the performance of floor system inappropriately. In the future, the rating method should be examined how the standard impact sources are similar with real sources in the point of rating the performance of floor system.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.46-56
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• 1999

A semi-actively controlled impact system which adjusts an impulse exerted by the external impact is studies. The main control variables are internal pressure difference inside the cylinder and the shock absorber displacement while it travels. Compared to a conventional one so called a passive system with a variable orifice inside the cylinder, a semi-actively controlled system utilizes an external orifice controlled by a highly fast responding electrical proportional valve. This device overcomes the temperature and viscosity change due to continuous operating and keeps the desired pressure difference and displacement in every operation. In this article a new prototype impact system is designed and manufactured based on a semi-actively control system. Through computer simulations and experiments, we verify the possibility of controlling the shock absorber pressure and displacement. After investigating the control performance a modified semi-actively controlled system with better control performance is also proposed.