• Journal of the Society of Naval Architects of Korea
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• v.40 no.4
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• pp.66-74
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• 2003

In non-contact underwater explosion shock test of a real naval ship, measurement of shock loadings and responses should require onboard system to be able to safely trigger an explosive and to simultaneously and successfully measure scores of shock signals in the deteriorated environment. For this purpose, we have developed a shock-hardened measurement system resistible to 170g peak acceleration having 4 msec duration by resiliently mounting general purpose measurement instruments in racks. The system can simultaneously measure and record 200 signals to evaluate shock leadings and responses of the test ship by triggering an explosive and measurement instruments at the same time. We prove the performance of the developed system by introducing the signal acquisition results from of a real ship underwater shock test, firstly performed in Korea.

• Korean Journal of Applied Biomechanics
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• v.22 no.2
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• pp.243-251
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• 2012

The purpose of this study was to develop an impact force measurement device in order to facilitate the acquisition of quantitative data for the analysis of various sporting events. The device was designed to include cylindrical aluminum supports of 220 mm diameter, which allows mounting and dismounting of the device on walls and frames. In addition, a hard sponge for impact absorption, as well as 4 springs, were attached to the plate. Both were attached to prevent psychological variables and injuries. When a subject applies force on the device, accurate data about the maximum repulsive force is acquired in real time, with a lag of only 0.001 s. The device was calibrated in four steps: (1) increase, (2) increase, (3) increase-decrease, and (4) increase-decrease. The maximum relative expanded uncertainty was 0.166%, indicating that the impact force measurement was sufficiently reliable. The proposed device can be applied to various sporting situations and is expected to be useful for studying kinetics.

• Nuclear Engineering and Technology
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• v.29 no.2
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• pp.167-174
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• 1997

The method that the operating condition of Control Rod Drive Mechanism (CRDM) can be monitored without mounting sensors within CRDM housing was developed, and by using this developed method the closed-loop controller for the CRDM was designed which can optimize the performance and maximize the reliability of CRDM operation. Neural network is utilized as pattern recognition engine in detecting CRDM actuation. In this paper, most problems in previous open loop system are resolved. The control algorithms for closed-loop system ore developed and implemented within the hardware of timing controller based on microprocessor. All functions in the timing controller ore verified by means of real time CRDM simulator. The results show that the timing controller performs its intended functions properly.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.148-152
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• 2000

Detection of tool wear is very important in automated manufacturing. This paper presents tool condition monitoring system based on the wavelet analysis of the AC servo motro current in drilling and milling process. The current measurement system is relatively simple and its mounting will not affect machining operations. The discrete wavelet transform was used to decompose the current signal of a spindle AC servo motor in time - frequency domain. The feature vectors were extracted from the decomposed signals and compared for normal and wear condition. The results show the possibility for the effective application of wavelet analysis to tool condition monitoring.

• Structural Engineering and Mechanics
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• v.3 no.6
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• pp.569-581
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• 1995

In this paper, the seismic behavior of a 10-story building equipped with viscoelastic dampers is analyzed. The effects of ambient temperature, the thickness, the total area, and the position of the viscoelastic dampers are studied. Results indicate that the energy-absorbing capacity of viscoelastic damper decreases with increasing the ambient temperature. The thickness and the total area of viscoelastic dampers also affect the seismic mitigation capacity. The thickness cannot be too small, which is not effective in vibration reduction, nor can it be too large, which not only increases the cost but also reduces the seismic resistance. The total area of viscoelastic dampers should be determined properly for optimum damper performance at the most economical design. The mounting position of viscoelastic dampers also influences the structure's seismic performance. Numerical results show that, if properly equipped, the VE dampers can reduce the structural response both floor displacement and story shear force and increase the overall level of damping in structures during earthquakes.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.2
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• pp.139-147
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• 2020

In this paper, design measure were proposed for the construction of terminal systems for airborne platforms, which are key element in the Joint Tactical Data Link System (JTDLS) complete system. The Korean perfect tactical data link (JTDLS) is a communication system to establish an independent tactical data link network and needs to develop a MIDS-LVT (Link-16) communication terminal for datalink. Once a Ground/Navy JTDLS terminal system is established around airborne platform, it will be possible to break away from reliance on NATO-based tactical data link joint operations and establish independent Korean surveillance reconnaissance real-time data sharing and tactical data link operations concepts. in this paper, the essential development elements of airborne platform mounting and operable JTDLS terminals are presented, and the concept of system design is proposed to embody them. Further, improved system performance was analyzed by applying the concepts of complex relative navigation system and Advanced TDMA protocol for the deployment of airborne tactical datalink networks.

• Journal of the Semiconductor & Display Technology
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• v.5 no.1 s.14
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• pp.1-4
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• 2006

Recently, Ball Grid Arrays(BGAs) are getting used more frequently for a package type. The connectors on a BGA consist of a large number of small solder balls in a grid shape on its bottom side. However, since balls of BGAs mounted on PCBs are not visible, inspection before mounting them is indispensable. High speed non-contact 3D measurement technologies are necessary far real-time measurement of ball height, the most important inspection item. In this paper, an accurate 3D data acquisition system for BGAs is proposed that can acquire 3D profile at high speed using a 3D smart camera and laser slit ray projection. Some clipping and morphological filtering operations are employed to remove spiky error data, which occur due to reflections from some ball area to camera direction.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.2
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• pp.122-128
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• 2010

This paper presents vibration control performance of active engine mount system installed with the magneto-rheological(MR) mount and the piezostack mount. The performance is evaluated via hardware-in-the-loop-simulation(HILS) method. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three point mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. As a second step, sliding mode controller(SMC) is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds(wide frequency range) using HILS method and presented in time and frequency domain.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.857-860
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• 2003

We introduced the basic direction of revision for KS F 2805 (method for measurement of sound absorption coefficient in a reverberation room). It is fundamentally equal to ISO 354 (measurement of sound absorption in a reverberation room) which was state of ISO/FDIS 354. Two main points were strongly reviewed. First, the sound absorption coefficient values for Type J test specimen mounting was investigated. Next, the reverberation time difference between the conventional method and new additional one, impulse response method were compared.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.701-709
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• 2001

In this days, heat pipe heat sink has been widely applied to power controllers for railway substations to remove heat from power semiconductors(diodes or thyristors). The heat pipe heat sink consists of a aluminum heating block for mounting the thyristor, 2~3 heat pipes and large number of aluminum fins. The present study was to get fundamental informations of the structure, design parameters and heat transfer performances of heat pipe heat sink. Series of operational test for a unit with 3 heat pipes were performed and its heat flow circuit was analysed from the experimentally obtained data on wall temperature distribution. Total resistance was ranged 0.02~$0.03^{\circ}C$/W for a power range from 40W to400W. The time to get the steady state was approximately longer than 20 minutes, and overshooting was not occurred during start up operation.