• Explosives and Blasting
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• v.35 no.3
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• pp.15-20
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• 2017

In order to obtain the dynamic response behavior of the rock subjected to blasting loading, a shock-proof high sensitivity impact sensor which can measure high frequency dynamic force and strain events should be adopted. Because the impact sensors which uses quartz and piezoelectric element are costly, generally the strain measurement-based impact (SMI) sensors are applied to high speed loading devices. In this study, dynamic Brazilian tension tests of granitic rocks was conducted using the Nonex Rock Cracker (NRC) reaction driven-high speed loading device which adopts SMI sensors. The dynamic response of the granite specimens were monitored and the intermediate strain rate dependency of Brazilian tensile strengths was discussed.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.6
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• pp.591-596
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• 2016

This paper presents a study on the subject for the design and implementation of high-speed frequency hopping RF transceiver used for tactical communications systems. Jump the transmission / reception frequency of the L-band to hop tens per second is possible by maximizing the immunity to interference, and is applicable to communication systems having a charging rotation function. To high-speed frequency hopping it is necessary to apply the necessary fast frequency hopping scheme DDS Driven PLL added. In this paper, the RF transceiver design and simulation analysis capabilities with fast frequency tactical communication systems, were implemented after the main test for functionality and performance. Was demonstrated hop high-speed jump tens per second through a test, the main transmission output, were measured RF key performance, such as received noise figure, by using the VSG and VSA generates a ${\pi}/4$ DQPSK modulated signal constellation and by EVM measurement that there is no problem in applying the communications system described above was pre-validated.

• Geotechnical Engineering
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• v.13 no.5
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• pp.75-88
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• 1997

In this study an iterative procedure for the analysis of drilled shafts was proposed on the basis of the load transfer mechanism. Special attention was given to the estimation of bearing capacity of drilled shafts which was compared with driven piles, and then with the results of pile load test. The load displacement at the pile head was calculated by load than sfer curves (t -z curves, q-z curves) by using Vljayvergiya, Castelli and hi -linear models. Bab ed on the analytical results, it is found that the behavior of drilled shafts is different from that of driven piles the smaller the skin friction mobilized at the pile-boil interface, the smaller the development of the bearing capacity. Hence the greater pile head movement is required to mobilize the same mainitride of bearing capacity. This trend is more noticeable in sand than in clay. It is also found that as the length-todiameter ratios increase, the dirtference of ultimate bearing capacity between drilled shafts and driven piles is becoming lass ger in sand, but it is minor in clay.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.242-249
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• 2009

High-rise construction sites, especially those situated in spatially constrained urban areas, have difficulties in timely delivery of materials. Modern techniques such as Just-in-time delivery, and use of information technology such as Project Management Information System (PMIS), are targeted to improve the efficiency of the logistics. Such IT-driven management techniques can be further benefited from state-of-the-art devices such as Radio Frequency Identification (RFID) tags and Ubiquitous Sensor Networks (USN), which has resulted in notable achievements in automated logistics management at the construction sites. Based on those achievements, this research develops USN hardware toolkits for construction lifts, which aims to be automated the vertical material delivery by sensing the material information and routing it automatically to the right place. The gathered information from the sensors can also be used for monitoring the overall status. The developed system will be tested in the actual high-rise construction sites to assess the system's feasibility. The proposed system is being implemented using Zigbee communication modules and RFID sensor networks which will communicate with the intelligent palette system (previously developed by the authors). To support the system, a lift-mountable intelligent toolkit is under development. Its feasibility test will be conducted by applying the implemented system to a test bed and then analyzing efficiency of the system and the toolkit. The collected test data will be provided as a basis of autonomous vertical transport equipment development. From this research, efficient management of the material lift is expected with increased accuracy, as well as better management of overall construction schedule benefited from the system. Further research will be expected to develop a smart construction lift, which will eliminate the need for human supervision, thus enabling a real 'autonomous' operation of the system.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.517-522
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• 2005

A cold storage refrigerator using phase change material(PCM) has been developed and its performance test results are provided here. The inner temperature of the refrigerator is controlled with forced convection driven by a fan using a DC battery. At the first, to freeze all the PCM of the ambient temperature by a built-in refrigerating machine, it took about 8 and 10 hours respectively at the refrigerator and the freezer mode. Then, without external power supply, the inner temperature of the cold storage refrigerator has been maintained at $-18{\pm}1^{\circ}C$ during 14 hours at the freezer mode and maintained at $3{\pm}^{\circ}C$ during 34 hours at the refrigerator mode. Just after the end of its valid usage as a refrigerator or a freezer, it took about 6 hours to refreeze the PCM for its reuse. During the test, the ambient temperature was kept at $30^{\circ}C$.

• The KIPS Transactions:PartD
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• v.16D no.4
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• pp.595-612
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• 2009

The early test can greatly reduce the cost of error correction for system development. It is still important in SOA based service system. However, the existing methods of test case generation for SOA have limitations which are restricted to only web service using XML. Therefore, this paper proposes a method of test case generation using BPMN-based model reduction for service system. For minimizing test effort, an existing BPM is transformed into S-BPM which is composed of basic elements of workflow. The process of test case generation starts with making S-BPM concerning the target service system, and transforms the target service system into directed graph. And then, we generate several service scenarios applying scenario searching algorithm and extract message moving information. Applying this method, we can obtain effective test cases which are even unlimited to web service. This result is the generation of test case which is reflected in the business-driven property of SOA.

• Ocean and Polar Research
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• v.26 no.2
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• pp.333-339
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• 2004

This paper is concerned with an experimental investigation about tractive performance of a tracked vehicle on extremely soft soil. A tracked vehicle model with principal dimensions of $0.9\;m(L)\;{\times}\;0.75\;m(B)\;{\times}\;0.4\;m(H)$ and the weight of 167 kg was constructed with a pair of driving chain links driven by two AC-servo motors. The tracks are configured with detachable grousers with variable span. Deep seabed was simulated by means of bentonite-water mixture in a soil bin of $6.0\;m(L)\;{\times}\;3.7\;m(B)\;{\times}\;0.7\;m(H)$. Slip of vehicle and driving torque of motor were measured with respect to experimental variables; grouser span, grouser chevron angle, driving speed, drawbar-pull weight, position of center-of-gravity and weight. $L_8$ orthogonal array is adopted for DOE (Design Of Experiment). The effects of experiment variables on traction performance are evaluated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2373-2380
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• 1993

This paper addresses the design procedure and testing result of a servo driven pan/tilt device which is capable of tracking arbitrary movement of a specified target object. In order to achieve real-time acquisition of feedback signal, a 2 degree-of freedom non-contact type displacement follower has been employed in stead of vision camera. The performance of the designed system is tested for different target velocities and control gains. The test result shows the satisfactory performance to be adopted as an effective tool for visual transfer in the context of teleoperation.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.545-550
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• 2004

KSTAR cryostat is a 8.8 m diameter vacuum vessel that provides the necessary thermal barrier between the ambient temperature test cell and the supercritical helium cooled superconducting magnet providing the base pressure of 1 ${\times}$ $10^{-3}Pa$. The cryostat is a single walled vessel consisting of central cylindrical section and two end closures, a flat base structure with external reinforcements and a dome-shaped lid structure. The base structure has 8 equally spaced support legs anchored on the concrete base. The cryostat vessel design was executed to satisfy the performance and operation requirements. The major loads considered in the structural analysis were vacuum pressure, dead weight, electromagnetic load driven by plasma disruption, and seismic load. Based on the fabrication and inspection procedures for the vessel, cryostat vessel was fabricated and inspected. It was confirmed that the inspection results were acceptable.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.151-153
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• 2007

Recently study on components for a electric golf car and a utility car driven by a electric motor has been performed actively, and the study on a drive motor, a inverter and a battery focuses on a small, light weight and high power density source to improve fuel efficiency using limited electric energy. Especially, since a utility car such as a golf car performance depends on initial acceleration and maximum speed capability, a drive system requires high power and large and wide operation area, This study therefore investigates on the interior permanent magnet synchronous motor with high power density and wide operation, and is verified with the test result after design and characteristic analysis is performed.