• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.461-467
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• 2003

This paper proposes the method of mobility implementation for location searching in the intelligence wireless ATM networks that expand and apply standard broadband signaling capabilities, and analyze the performance based on the numerical algorithm. The existing B-ISDN UNI protocol stack demands the location search mechanism to determine the location of mobile terminal in the wireless ATM networks because it use single protocol through the fixed PTP interface or PTM interface that don't support terminal mobility. The proposed method make possible the dynamic mobility at a part of wireless access by minimizing the signaling load without a falling-off in system performance by using the intelligence network technology according to the expansion of ATM and B-ISDN signaling integration based on the fixed networks. We implemented the performance analysis by MFC modeling based on numerical algorithm, and realized the efficiency of expenses by carrying out the comparative signaling performance evaluation to measure the relative gains of location search service in the intelligence wireless ATM system. The obtained results have the flexibility to operate in the public B-ISDN network environment without a change of existing B-ISDN/ATM NNI signaling reference to support the wireless ATM access system, and can easily expand to correspond to terminal mobility and various multimedia services in the next broadband PCS.

• Geophysics and Geophysical Exploration
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• v.4 no.4
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• pp.133-144
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• 2001

An effective seismic reflection technique for mapping the cavities and bedrock surface in carbonate rocks is described. The high resolution seismic reflection images were successfully registered by using the hydrophones employed in the stream-water driven trench, and were effectively focused by applying optimal data processing sequences. The strategy included enhancement of the signal interfered with the large-amplitude scattering noise, through pre- and post stack processing such as time-variant filtering, bad-trace editing, residual statics, velocity analysis, and careful muting after NMO (normal moveout) correction. The major reflections including the bedrock surface were mapped with the desired resolution and were correlated to the seismic crosshole tomographic data. Shallow major reflectors could be identified and analyzed on the AGC (auto gain control)-applied field records. Three subhorizontal layers were identified with their distinct velocities; overburden (<3000 m/s), sediments (3000-4000 m/s), limestone bedrock (>4000 m/s). Taking into account of no diffraction effects in the field records, gravel-rich overburdens and sediments are considered to be well sorted. Based on the images mapped consistently on the whole survey line and seismic velocity increasing with depth, this area probably lacks in sizable cavities (if any, no air-filled cavities).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.303-310
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• 2008

We fabricated hydrogenated amorphous silicon(a-Si:H) 140 nm thick film on a $180\;nm-SiO_2/Si$ substrate with an inductively-coupled plasma chemical vapor deposition(ICP-CVD) equipment at $250^{\circ}C$. Moreover, 30 nm-Ni film was deposited with a thermal-evaporator sequently. Then the film stack was annealed to induce silicides by a rapid thermal annealer(RTA) at $200{\sim}500^{\circ}C$ in every $50^{\circ}C$ for 30 minuets. We employed a four-point tester, high resolution X-ray diffraction(HRXRD), field emission scanning electron microscope(FE-SEM), transmission electron microscope(TEM), and scanning probe microscope(SPM) in order to examine the sheet resistance, phase transformation, in-plane microstructure, cross-sectional microstructure evolution, and surface roughness, respectively. We confirmed that nano-thick high resistive $Ni_3Si$, mid-resistive $Ni_2Si$, and low resistive NiSi phases were stable at the temperature of <300, $350{\sim}450^{\circ}C$, and >$450^{\circ}C$, respectively. Through SPM analysis, we confirmed the surface roughness of nickel silicide was below 12 nm, which implied that it was superior over employing the glass and polymer substrates.

• Fire Science and Engineering
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• v.30 no.3
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• pp.31-40
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• 2016

Recently, a curtain wall system was applied to skyscrapers to prevent fire spreading along the vertical direction due to stack effect and outside air flow when a fire breaks out in skyscraper. Conventional sprinklers cannot prevent the spread of fire to the upstairs areas, which increases the loss of life and property. In this study, a water curtain nozzle that creates wider water coverage on the surface of glass and can prevent the spread of fire to the upstairs areas was developed. The spray pattern of the water curtain nozzle was compared with that of a sprinkler to determine performance of the water curtain nozzle. A fire experiment was constructed on the second floor to verify performance of the water curtain nozzle in preventing the spread of fire to the upstairs areas. The fire and watering experiment proved that the water curtain nozzle prevented more effectively the spread of fire than the conventional sprinkler. The position of first crack and critical temperature of fracture were also analyzed using numerical analysis.

• Journal of Internet Computing and Services
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• v.14 no.5
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• pp.27-38
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• 2013

Currently a number of managers exist to manage heterogeneous networks, in this situation, the NETCONF protocol for efficient network management has been proposed as a new protocol. However, the standard NETCONF protocol stack continuous improvement since the establishment but in four layers still have some problems. Especially in situations where there are multiple administrators, problems are more highlighted in operation layer. In this paper, we focus on these issues and the Operation layer has improved the efficiency and flexibility of operations among NETCONF four layers. Additionally, for the inefficiency of updates improved the device settings based on improved operation techniques. In addition, standard protocol NETCONF did not proposed content layer data structure and we propose standard technique of content layer that can generate configuration structure of devices. Improved the three techniques are applied appropriately to the NETCONF, the proposed method and the existing NETCONF was performed experiment to compare with experimental four factors. Compare key factor are four kind as maintaining the probability of network function, the reaction performance about command, the number of control packets, performance of data creation in content layer. Such factors after performing the experiment, the proposed method in this paper is superior to the existing NETCONF and there was confirmed by analysis Experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.5
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• pp.271-279
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• 2014

In this paper, the two design techniques of the embedded system which provides a wireless image observation with temporary ad-hoc network are proposed and developed. The first method is based on the embedded system design technique for a nearly real-time wireless short observation application, having a specific remote monitoring node with a built-in image processing function, and having the maximum rate of 1 fps (frame per second) wireless image transmission capability of a $160{\times}128$size image. The second technique uses the embedded system for a general wireless long observation application, consisting of the main node, the remote monitoring node, and the system controller with built-in image processing function, and the capability of the wireless image transmission rate of 1/3 fps. The proposed system uses the wireless ad-hoc network which is widely accepted as a short range, low power, and bidirectional digital communication, the hardware are consisted of the general developed modules, a small digital camera, and a PC, and the embedded software based upon the Zigbee stack and the user interface software are developed and tested on the implemented module. The wireless environment analysis and the performance results are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.227-233
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• 2014

This study investigates the vibration characteristics of a wire-bonding piezoelectric transducer and ultrasonic horn for high-speed and precise welding. A ring-type piezoelectric stack actuator is excited at 136 kHz to vibrate a conical-type horn and capillary system. The nodal lines and amplification ratio of the ultrasonic horn are obtained using a theoretical analysis and FEM simulation. The vibration modes and frequencies close to the driving frequency are identified to evaluate the bonding performance of the current wire-bonder system. The FEM and experimental results show that the current wire-bonder system uses the bending mode of 136 kHz as the principal motion for bonding and that the transverse vibration of the capillary causes the bonding failure. Because the major longitudinal mode exists at 119 kHz, it is recommended that the design of the current wire-bonding system be modified to use the major longitudinal mode at the excitation frequency and to minimize the transverse vibration of capillary in order to improve the bonding performance.

• Journal of Climate Change Research
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• v.4 no.3
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• pp.235-244
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• 2013

Carbon dioxide emission estimation methods consist of four tiers according to the IPCC guideline. In this study, estimated results by tier 3 and tier 4 were compared with the theoretically calculated $CO_2$ emissions based on the mass balance approach for a gas fired power plant between March and May 2011. It was found that the relative differences were upto 17% between the measured emissions by tier 4 and theoretically estimated emissions, while the results of tier 3 were similar to those from theoretically estimated ones. The comparisons suggested the possibility of misestimation due to replacing missing, abnormal, or invalid data in continuous emissions monitoring system. When using only the data without those missing, abnormal, or invalid data, the relative differences decreased somewhat but still showed consistent differences depending on the stack. It is suggested that this differences might be due to the accuracy of the measurement instruments for the tier 4, especially, for the flow rate measurement instrument.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.65-75
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• 2018

The wind energy produced at night is being discarded because of the excess power generated at night compared to daytime. To solve this problem, In this study, we analyzed the evaluation contents for evaluation of domestic and overseas water electrolysis systems and drew contents for safety performance contents test of the water electrolysis system based on the evaluation contents. The test contents produced the efficiency measurement test, the hydrogen generated pressure test, and the hydrogen purity test. And the safety performance evaluation of the alkaline water electrolysis system of $5Nm^3/hr$ was performed based on the results. As a result, the hydrogen generation was calculated as $5.10Nm^3/hr$ and the stack efficiency was $4.97kWh/Nm^3$. The purity of the hydrogen generated was 99.993% and it was confirmed that it produced high purity hydrogen. I think will help us assess and build safety performance of water electrolysis systems in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.203-210
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• 2019

A recent earthquake on the Korean Peninsula caused much damage to masonry buildings, and research on performance evaluation has been underway. A masonry building is generally constructed using wet construction and is affected by temperature, which reduces the efficiency of the construction. In this study, we propose a dry construction technique for assembling concrete blocks without using mortar and evaluated its performance through experimental and analytical research. To evaluate the performance, experiments were carried out for the prismatic compressive strength, direct terminal strength, and diagonal tensile strength of the dry construction wall. The adequacy of the cross section shape was also reviewed through FEM analysis. The results show that the compressive strength and diagonal tensile strength could exert a certain intensity or higher. Furthermore, the H-type module of a key block acted as a shear key for the entire concrete block, which resulted in excellent shear strength performance. In addition, the shape and thickness of the main block have a major effect on the strength performance of each block. Therefore, an optimal shape and the proposed dry construction method could be applied to replace the wet method by studying the construction or seismic performance of the proposed method.