• Proceedings of the Korea Multimedia Society Conference
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• 1998.04a
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• pp.333-338
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• 1998

본 논문에서는 AAL-2/ATM 통신망 환경에서 멀티미디어 통신을 구현하기 위한 멀티미디어 동기화 기능으로 VGC 기반의 SRTS/AAL-2를 제안한다. 제안된 멀티미디어 동기화 알고리즘에서는 가변 비트율 멀티미디어 정보의 클럭 주파수 복원을 위하여 VGC(Virtual Global Clock)을 구성하고, 이를 기반으로 한 SRTS방식의 미디어 내부 동기와, MM-SSCFS(Multimedia-SSCS)/AAL-2 프로토콜을 사용한 미디어 간의 동기를 유지하는 방법을 제안하였다. 본 논문의 실험 환경으로는 Fore ATM 교환기(155 Mbps $\times$8 port)를 사용해서 소규모 B-ISDN/ATM 통신망을 구성하였고, SUN Workstatin Solaris 2.5에 접속된 Fore ATM 접속 카드 SBA-200에서 지원하는 XTI(X/Opne Transport Interface)-API를 사용하였다.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.390-395
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• 2002

The experimental and numerical study has been conducted on the sleeve repair welding of API 5L X65 pipeline. SMA W and GTAW were applied to weld the sleeve. The macrostructure and hardness of repair welds have been examined. The [mite element analysis of the multi-pass sleeve-fillet welding has been conducted to validate the experiment and investigate the effects of in-service welding conditions. The effect of gas flow rate on the hydrogen cracking was investigated. The effect of internal pressure on residual stresses and plastic strain was investigated. The allowable heat input was predicted considering the maximum temperature of inner surface of pipe and cooling rate at CGHAZ.

• Corrosion Science and Technology
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• v.6 no.3
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• pp.96-102
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• 2007

The resistance of the linepipe steel to hydrogen-induced cracking (HIC) and sulfide stress cracking (SSC) is very important for steel to be used in sour oil/gas environments. Welding of steels is necessary to the construction of pipe-line transporting oil/gas. In this study, HIC and SSC resistance of an electric resistance welded (ERW) steel plate which belongs to API X70 grade was evaluated by using NACE TM0284-96A and NACE TM0177-96A methods. HIC and SSC fracturing behavior was investigated by observing fractured surfaces using optical microscopy (OM) and scanning electron microscopy (SEM). It was discussed in terms of metallurgical parameters such as the distribution of primary microstructure, second phases and inclusions. Results showed that the weld joint of ERW steel is more sensitive than base metal to HIC and SSC. This is due to difference in the contribution of metallurgical parameters to HIC and SSC nucleation and propagation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.245-246
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• 2006

For developing 5-axis laser cutting systems, many problems such as rotating of laser head or table, 5-axis tool path generation and collision avoidance between laser head and product should be solved. In this paper, a five-axis laser cutting machine with table swivel and rotary type configuration is developed. The five axes (X,Y,Z,A,B) are controlled and interfaced to PC via MMC board. Two kinds of CAM S/W such as commercial 5-axis CAM S/W(Euclid) and UG-API are engaged to generate NC code for the developed 5-axis laser cutting machine.

• Journal of Electrochemical Science and Technology
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• v.8 no.2
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• pp.115-123
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• 2017

Electrochemical noise signals in many cases exhibit a DC drift that should be removed prior to further data analysis. Polynomial fitting and moving average removal method have been used to remove trends of electrochemical noise (EN) in time domain. The corrosion inhibition of synthesized schiff base N,N'-bis(3,5-dihydroxyacetophenone)-2,2-dimethylpropandiimine on API-5L-X70 steel in hydrochloric acid solutions were used to study the effects of drifts removal methods on noise resistance calculation. Also, electrochemical impedance spectroscopy (EIS) was used to study the corrosion inhibition property of the inhibitor. The results showed that for the calculation of $R_n$, both methods were effective in trend removal and the polynomial with m=4 and MAR with p=40 were in agreement.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.04a
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• pp.818-819
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• 2016

지오코딩(Geocoding)은 자연어로 표현된 주소를 컴퓨터가 인지 가능한 (x,y) 좌표로 변환하는 과정이며, 지리정보 분석 등 다양한 영역의 필수적인 전처리 과정에서 사용된다. 현재 국내 주소를 지오코딩하는 API를 제공하는 서비스 프로바이더는 다수 존재하나, 성능 향상의 여지가 남아있는 현황이다. 본 연구에서는 지오코딩 위치정확도의 향상을 위해 Euclidean/Edit distance 기반 앙상블(Ensemble) 지오코딩 알고리즘(EEE-Geocoding)을 제안하였다. 화학물질 보유 업체 5569개소의 주소를 토대로 제안 기법에 대한 성능평가 실험을 진행하였으며, 평가결과는 0.99 precision, 0.87 recall, 0.92 F1 score 이었다.

• Corrosion Science and Technology
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• v.8 no.4
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• pp.133-138
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• 2009

For the corrosion protection of the natural gas transmission pipelines, two methods are used, cathodic protection and coating technique. In the case of cathodic protection, defects are embrittled by occurring hydrogen at the crack tip or material surface. It is however very important to evaluate whether cracks in the embrittled area can grow or not, especially in weld metal. In this work, on the basis of elastic plastic fracture mechanics, we performed the CTOD testing with various test conditions, such as testing rate and potential. The CTOD of the base metal and the weld metal showed a strong dependence of the test conditions. The CTOD decreased with decreasing testing rate and with increasing cathodic potential. The morphology of the fracture surface showed the quasi-cleavage at low testing rate and cathodic overprotection. The low CTOD was caused by hydrogen embrittlement at crack tip.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.288-290
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• 2005

Apparent mechanical properties in structural components can be different from the initially designed values due to the formation of the residual stress in metal forming and welding. Therefore, the evaluation of residual stress has great importance in the reliability diagnosis of structural components. A nondestructive continuous indentation technique has been proposed to evaluate various strength concerning mechanical properties from the analysis of load-depth curve. In this study, quantitative residual stress estimation on API X65 welded joints for natural gas pipeline was performed by analyzing the variation of indentation loading curve by residual stress through a new proposed theoretical model.

• Corrosion Science and Technology
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• v.15 no.1
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• pp.13-17
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• 2016

The aim of this study was to evaluate the use of iron-nickel oxide ($Fe_2O_3$.NiO) nanopowder (FeNi) as an anti-corrosion pigment for a different application. The corrosion protection ability and the mechanism involved was determined using aqueous solution of FeNi prepared in a corrosive solution containing 3.5 wt.% NaCl. Anti-corrosion abilities of aqueous solution were determined using electrochemical impedance spectroscopy (EIS) on line pipe steel (API 5L X-80). The protection mechanism involved the adsorption of metallic cations on the steel surface forming a protective film. Analysis of EIS spectra revealed that corrosion inhibition occurred at low concentration, whereas higher concentration of aqueous solution produced induction behavior.

• Ocean Systems Engineering
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• v.5 no.1
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• pp.31-40
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• 2015

Three dimensional (3D) non-linear finite element analysis of offshore pipeline is investigated in this work with the help of general purpose software Abaqus. The general algorithm for the finite element approach is introduced. The 3D seabed mesh, limited to a corridor along the pipeline, is extracted from survey data via Fledermous software. Moreover soil bearing capacity and coefficient of frictions, obtained from the field survey report, and are introduced into the finite element model through the interaction module. For a case of study, a 32inch pipeline with API 5L X65 material grade subjected to high pressure and high temperature loading is investigated in more details.