• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.4
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• pp.503-512
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• 2024

In the seismic design standard, input waves for different levels of seismic performance are proposed in the form of design response spectra. At the time of establishing these standards, measured records of significant earthquakes that occurred domestically, such as the 2016 Gyeongju earthquake and the 2017 Pohang earthquake, were not included. Additionally, for the ground response analysis, shear wave velocities representing ground amplification characteristics were derived from the results of standard penetration tests (N-values) and applied in empirical formulas. This approach may not adequately capture sufficient information about the characteristics of domestic ground properties. Therefore, in this study, seismic records from the Gyeongju and Pohang earthquakes were modified to adjust the bedrock standard design response spectra. Ground response analyses were conducted using shear wave velocity profiles obtained from borehole tests in the Sejong City area. The shape of the response spectrum and ground amplification coefficient obtained from the ground response analysis were then compared with those from existing studies and seismic design standard.

• The Journal of Korean Association of Computer Education
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• v.8 no.1
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• pp.55-63
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• 2005

Recently, web-based E-learning systems have entered the spotlight by providing new learning environments that break down spatial and temporal limitations. The key to building the web-based E-learning system is in determining how to effectively use the system and to evaluate the degree of learning achieved by the students that use it. In traditional off-line learning systems, we can evaluate students by counting how many questions, designed to evaluate their learning achievement, he or she answers correctly within a predetermined time limit. But this method would make individualized learning, a strong point of E-learning systems, impossible because these systems provide same learning strategy to all students even though they achieve a different level of learning. Therefore, in this paper, I will find any relationships between given test answers using fuzzy implication theory, I call these fuzzy correlations, and then generate evaluation results that are reflected in those relationships. I will compare the differences between this evaluation method and a traditional evaluation method where a student takes a test to evaluate his or her learning achievement after some learning period. Finally, I will discuss how we can use these results in individualized learning.

• Fire Science and Engineering
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• v.22 no.3
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• pp.239-245
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• 2008

In this study, we researched about characteristics of many kinds of tank cars for carrying hazard materials and performed structural strength evaluation using finite element analysis for tank of asphalt tank car to suggest the efficient analysis method that can develop accuracy regarding to characteristics of tank cars. For this, we analyzed the asphalt tank refer to JIS E 7102 (Design Method for Tanks of Tank Cars). As results, we could show that the maximum stress is applied at the area supported by saddle and the maximum stress is under a criterion suggested from JIS E 7102. Therefore we verified that this asphalt tank car had enough structural strength.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1436-1445
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• 1990

Performance of vehicles depends mainly on engine performance, transmission gear ration and shifting pattern. In this paper, determination method of gear ratios and shifting pattern for automatic transmission equipped vehicles has been proposed. Computer programs for gear ratio determination and shifting pattern decision using optimal design technique have been developed for the purpose of increasing vehicle acceleration performance. For preceding study, computer simulation of vehicle performance is carried out using numerical technique.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.1
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• pp.27-38
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• 2000

The collapses and settlement of harbor facilities from earthquakes were known due mostly to liquefaction of reclaimed land. The most harbor quay wa1ls being designed as gravity types in Korea are known susceptible structures to liquefaction because reclaimed land was not treated resistant to earthquake. In this study, liquefaction susceptibility of reclaimed land behind a large quay walls under construction to earthquake was predicted and its stability was analyzed. In addition, liquefaction prediction methods in harbor facilities specification adopted by both Korea and Japan were compared by applying the methods to prediction of liquefaction susceptibility of reclaimed land, respectively.

• Journal of Auto-vehicle Safety Association
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• v.5 no.2
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• pp.45-50
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• 2013

The whiplash Injuries due to rear collision occur frequently. As result, in many countries, seat performance is being assessed and developed to improve head whiplash injury in rear collision of passenger car. This study compares whiplash assessment methods in each country. Using the DFSS(Design for Six Sigma) method, the correlation between influence parameters of head restraints and whiplash injury criteria is analyzed. Four control factors are used in this study. And total 11 whiplash injury criteria from NCAP(New Car Assessment Program) of Korea, Europe, China and IIHS(Insurance Institute for Highway Safety) of USA are used for output response. By the experimental design, L9 orthogonal coordinate system is configured and is tested by sled test equipment, twice. By using average assay value and ANOVA, the correlation between control factors and injury criteria has been comprehended. Optimization design of head restraint according the regional seat safety assessment was derived through the correlation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.148-153
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• 2017

During natural ageing of HTPB propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behaviour at different time-temperature conditions especially focused on the in-service conditions. Ageing behaviour of HTPB propellant were investigated using HFC(Micro-Heat Flow Calorimeter) is universal technique for measuring the rate of slow chemical and physical processes in long-term storage.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.47.2-47.2
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• 2009

인체의 뼈와 같은 손상된 경조직을 치료 또는 대체하기위한 정형외과용 임플란트를 설계하는데 있어 뼈의 생체역학적 특성과 유사한 성질을 갖는 다공성 지지체에 대한 연구가 최근 관심을 끌고 있다. 다공성 지지체는 조직이 원활히 재생될 수 있어야 하며, 또한 주변 조직과도 생물학적인 고착이 잘 되도록 기공들이 상호 연결된 구조를 가져야 한다. 이와 같은 다공성 지지체용 소재를 제조하기 위하여 본 연구에서는 타이타늄 분말을 사용하여 3차원 적층조형공정으로 다공성 타이타늄 지지체를 제조하였다. 제조된 다공체의 물성 및 기계적 특성을 평가하기 위하여 압축시험과 변형해석을 수행하였으며, 아울러 제조된 지지체의 생체적합성 향상을 위하여 양극산화 공정 등의 표면처리를 수행하여 그에 대한 특성을 평가하였다. 분말야금 공정으로 제조된 지지체는 골조직의 성장에 적합한 약 $300\sim400{\mu}m$의 기공 크기를 갖도록 제어하였고, 기공도는 60~75%로 제어하였다. 아울러 다공성 타이타늄의 생체적합성을 부여하기 위하여 양극산화공정으로 지지체의 표면에 Ca 및 P을 포함하는 산화층을 형성시키는 표면처리를 수행하였다. 양극산화공정에 의하여 표면에 미세기공을 포함하는 산화층을 형성시킬 수 있었으나 이와 같은 표면구조는 조골세포의 부착과 영향에는 큰 영향을 미치지 않는 것으로 확인되었다.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.905-909
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• 1995

We constructed the large 3-axis square Helmholtz coil system for the power frequency magnetic field immunity test. We measured the coil factors and magnetic field homogeneities of the fabricated 3-axis square Helmholtz coil. The experimental results for the field homogeneities are in agreement with the theoretical data. From these results, we determined the effective areas for the immunity test. We also confirmed that the low current using the multi-turns coil can be applicable to the immunity test for the high field in short duration.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.59-65
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• 2018

During natural aging, hydroxyl-terminated polybutadiene(HTPB) propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behavior at different time-temperatures focusing on in-service conditions. Aging behaviors of HTPB propellant are investigated using HFC(heat flow calorimeter), a universal technique for measuring the rate of slow chemical and physical processes in long-term storage.