• Journal of Internet Computing and Services
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• v.4 no.3
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• pp.47-55
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• 2003

Multicast protocols ore developed in order to support group communications efficiently, However. there still exist some issues to be solved for deploy multicast protocol in the public internet. This paper refers problem of existing Reliable Multicast Protocols and redesigns component function, and proposes enhanced reliable multicast transport protocol, This paper proposed a improved multicast transport scheme in NACK based reliable multicast. This scheme is much faster than by sender-initiated or receiver-initiated recovery and latency is smaller. Designed components are implemented in UNIX environment using C programming longuage. Then the protocol was evaluated performance through simulation. As the result, proposed protocol is better than existing protocols in both of transmission delay and packet loss. Especially, proposed protocol in this paper con be used in multicast services needed high reliability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1210-1215
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• 2010

The probe card are test modules which are to classify the good semiconductor chips and thin film before the packaging process. In the rapid growth a technology of semiconductor, the number of pads per unit area is increasing and pad arrays are becoming irregular. Therefore, the technology of probe card needs narrow width and lots of probe tip. In this paper, the probe tip based on the MEMS(Micro Electro Mechanical System)technology was developed a new MEMS probe tip for vertical probe card applications. For the structural designs of probe tip were performed to mechanical characteristics and structural analysis using FEM(Finite Element Method). Also, the contact force of MEMS probe tip compared with FEM results and experimental results. Finally, the MEMS probe card was developed a fine pitch smaller than $50{\mu}m$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.9-17
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• 2020

The purpose of this study was to evaluate lateral load resistance of a wall structure composed of precast concrete wall and H-Pile. This type of structure can be used for noise barrier foundation or retaining wall. Mock-up specimens having actual size were designed and fabricated. The lateral design load is 54.6kN. The H-pile length for the test specimen is 1.5m for simulating behavior of actual wall structure has 6.5m H-pile in the field, which is determined from theoretical study. Lateral displacements and strains of wall and H-pile were monitored and cracking in precast concrete wall inspected during the test. Load and deformation capacity of test specimens was compared with design capacity. The comparisons demonstrated that this type of structures, precast concrete wall and H-pile, can resist enough to lateral design load.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4199-4204
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• 2011

The dynamic modulus of hot mix asphalt is one of the important indicators to evaluate the durability and performance of asphalt pavement. In resent, the dynamic modulus is suggested by a key property of asphalt pavement design and analysis in AASHTO 2002 Design Guide and Korean Pavement Research Project(KPRP). Master curve from laboratory test results should be needed for pavement design and analysis. The process to get the master curve is standardized. But, there are some setup and testing error at low temperature(-$10^{\circ}C$) and high temperature ($55^{\circ}C$). In this paper, a simplified process which is used 3 testing temperatures (5, 21, 40) is adopted to get the master curve. Comparison was carried out for standard process and simplified process. The suggested process can be used to get the master curve of asphalt pavement, even though some difference was shown at high temperature.

• Journal of Korean Society of Steel Construction
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• v.17 no.6 s.79
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• pp.689-697
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• 2005

Recent test results on reduced beam section (RBS) steel moment connections show that specimens with a bolted web connection tend to perform poorly due to premature brittle fracture of the beam flange at the weld access hole. A review of previous test results indicates that the higher incidence of base metal fracture in bolted-web specimens is related, at least in part, to the web bolt slippage and the high stress concentration at the weld access hole with the lowest material toughness. The practice of providing web bolts uniformly along the beam depth based on the classical beam theory is questioned in this paper. A new seismic design procedure, which is more consistent with the actual load path identified from the analytical and experimental studies, is proposed together with improved connection details. A test specimen designed following the proposed procedure exhibited a cyclic connection rotation capacity sufficient for special moment frames without fracture.

• International Journal of Highway Engineering
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• v.5 no.4 s.18
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• pp.13-22
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• 2003

Several design methods from overseas are employed without considering different conditions such as material properties, climate, and traffic condition in this country. Therefore, there are limitations in application. Therefore, new pavement analysis system which is able to design a pavement efficiently and economically should be set up. In this study, 243 probable sections are classified depending on values of layer thickness and elastic modulus, and the effect of load types for the probable sections are analyzed. The section showing larger load distribution is chosen for analysis. As a result of sensitivity, a layer thickness has more influence on pavement than an elastic modulus does. The stress distribution of FWD test load is larger than that of circular load. This study compares outputs between nonlinear elastic model and linear elastic model. Based on the result, this study finds nonlinear elastic model considering stress condition in the ground is recommended for subbase.

• Tunnel and Underground Space
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• v.14 no.1
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• pp.1-15
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• 2004

The development of high-performance shotcrete lining is essential in improving the long-term durability of tunnels and in introducing single-shell tunnelling methods, where shotcrete as well as rockbolts are used as permanent support members. In this paper, new and advanced admixtures to improve shotcrete performance are introduced. In addition, requirements for mechanical properties as well as test items for quality control of shotcrete are summarized. A case study on the application of the pneumatic pin penetration test which can estimate compressive strength of shotcrete more easily and quickly is also illustrated. Previous studies to analyze the behaviors of shotcrete lining by considering its transient hardening and to carry out the sensitivity analysis of the design parameters of shotcrete lining are discussed to give fundamental concepts on rock-support interactions. Representative single-shell tunnelling methods where high-performance shotcrete lining is applied as a permanent support are also introduced.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.331-336
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• 2003

The advanced spent fuel conditioning process(ACP) was proposed to reduce considerably the overall volume and radioactivity for effective management of the PWR spent fuel in respects on safety and economy. The ACP is under research and development, and have scheduled to perform hot test for demonstration of the ACP after several years. For hot test, hot cell facility of ${\alpha}{\gamma}$ type possess conservative safety is required essentially. A existing hot cell of ${\beta}{\gamma}$ type will be refurbished to minimize construction expenditures of hot cell facility. In this study, the design requirements are established, and the process detail work flow was analysed for the optimum arrangement to ensure effective process operation in hot cell. And also, the basic and detail design of hot cell facility and process and safety analysis was peformed to secure conservative safety of hot cell facility and process.

• Fire Science and Engineering
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• v.24 no.2
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• pp.44-51
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• 2010

This study, to develop the technology of the fire resistance design of CFT structure based on fire resistance performance design, was suppose to use as basic data for performance design through a measure of temperature and deformation of the CFT specimen as parameter is the concrete compressive strength and load ratio. In accordance with KS F 2257-1 and 7, 24 MPa and 40 MPa and the load ratio of 0.9, 0.6 and 0.2 were imposed on a square column and as a result of evaluating in accordance with the fire resistance criteria, in case of 24 MPa, the fire resistance performance was improved by 73 minutes when the load ratio was reduced by 0.3. And when it comes to 40 MPa, the fire resistance was 31 minutes and 180 minutes when a load ratio was 0.6 and 0.2, respectively. As a result of evaluating fire resistant performance depending on variation of internal concrete strength, it proved that the higher the strength the lower the fire resistance.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.82-87
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• 2014

Dual pulse rocket motor has a rocket motor with different pulse grains divided by a pulse separation device such as a fragile bulkhead or a thermal barrier type. It distributes thrust energy very effectively via pulse separation device to improve range and terminal velocity of a missile. This paper contains the thermal barrier design and experimental analysis through ground firing tests of small dual pulse motors. The results will be applied to the design, test and evaluation of the scale up dual pulse rocket motor.