• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.577-585
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• 2023

Lateral torsional buckling causessafety accidentssuch as collapse accidents during erection. Therefore, anaccurate safety designshould be conducted. Lateral torsional buckling canbe prevented by reinforcing the end orreducing the unbraced length. The method ofreducing the unbraced length by installing a crossframe has high material and installation costs and low maintenance performance.In addition, structuralsafety may be deteriorated due to cracks. The end reinforcement method using Concrete Filled Half Pipe Stiffeneris a method ofreinforcing the end of a plate girder using a stiffenerin the form of a semi-circular column. This method increasesthewarping strength ofthe girder and increasesthe lateral torsional buckling strength.In thisstudy, the effect ofincreasing the warping strengthof plate girders with concrete filled half pipe stiffeners was confirmed. To verify the effect, the results ofthe designequationand the finite element analysis were compared and verified through a experiment. As a result, the plate girderwithCFHPS increased thewarping strengthand confirmed that the lateral torsional buckling strength was increased.

• Progress in Medical Physics
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• v.23 no.3
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• pp.145-153
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• 2012

In this study, we quantify the residual motion artifact in 4D-CT scan using the dynamic lung phantom which could simulate respiratory target motion and suggest a simple one-dimension theoretical model to explain and characterize the source of motion artifacts in 4DCT scanning. We set-up regular 1D sine motion and adjusted three level of amplitude (10, 20, 30 mm) with fixed period (4s). The 4DCT scans are acquired in helical mode and phase information provided by the belt type respiratory monitoring system. The images were sorted into ten phase bins ranging from 0% to 90%. The reconstructed images were subsequently imported into the Treatment Planning System (CorePLAN, SC&J) for target delineation using a fixed contour window and dimensions of the three targets are measured along the direction of motion. Target dimension of each phase image have same changing trend. The error is minimum at 50% phase in all case (10, 20, 30 mm) and we found that ${\Delta}S$ (target dimension change) of 10, 20 and 30 mm amplitude were 0 (0%), 0.1 (5%), 0.1 (5%) cm respectively compare to the static image of target diameter (2 cm). while the error is maximum at 30% and 80% phase ${\Delta}S$ of 10, 20 and 30 mm amplitude were 0.2 (10%), 0.7 (35%), 0.9 (45%) cm respectively. Based on these result, we try to analysis the residual motion artifact in 4D-CT scan using a simple one-dimension theoretical model and also we developed a simulation program. Our results explain the effect of residual motion on each phase target displacement and also shown that residual motion artifact was affected that the target velocity at each phase. In this study, we focus on provides a more intuitive understanding about the residual motion artifact and try to explain the relationship motion parameters of the scanner, treatment couch and tumor. In conclusion, our results could help to decide the appropriate reconstruction phase and CT parameters which reduce the residual motion artifact in 4DCT.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.263-272
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• 2012

Carbon dioxide, emitted by human activities since the industrial revolution, is regarded as a major contributor of global warming. There are many efforts to mitigate climate change, and carbon dioxide capture and geological storage (CCS) is recognized as one of key technologies because it can reduce carbon dioxide emissions from large point sources such as a power station or other industrial installation. The inclusion of CCS as clean development mechanism (CDM) project activities has been considered at UNFCCC as financial incentive mechanisms for those developing countries that may wish to deploy the CCS. Although the Conference of the Parties serving as the Meeting of the Parties to the UNFCCC's Kyoto Protocol (CMP), at Cancun in December 2010, decided that CCS is eligible as CDM project activities, the issues identified in decision 2/CMP.5 should be addressed and resolved in a satisfactory manner. Major issues regarding modalities and procedure are 1) Site selection, 2) Monitoring, 3) Modeling, 4) Boundaries, 5) Seepage Measuring and Accounting, 6) Trans-Boundary Effects, 7) Accounting of Associated Project Emissions (Leakage), 8) Risk and Safety Assessment, and 9) Liability Under the CDM Scheme. The CMP, by its decision 7/CMP.6, invited Parties to submit their views to the secretariat of Subsidiary Body for Scientific and Technological Advice (SBSTA), SBSTA prepared a draft modalities and procedure by exchanging views of Parties through workshop held in Abu Dhabi, UAE (September 2011). The 7th CMP (Durban, December 2011) finally adopted the modalities and procedures for CCS as CDM project activities (CMP[2011], Decision-/CMP.7). The inclusion of CCS as CDM project activities means that CCS is officially accredited as one of $CO_2$ reducing technologies in global carbon market. Consequently, it will affect relevant technologies and industry as well as law and policy in Korea and aboard countries. This paper presents a progress made on discussion and challenges regarding the issue, and aims to suggest some considerations to policy makers in Korea in order to demonstrate and deploy the CCS project in the near future. According to the adopted modalities and procedures for CCS as CDM project activities, it is possible to implement relevant CCS projects in Non-Annex I countries, including Korea, as long as legal and regulatory frameworks are established. Though Korea enacted 'Framework Act on Low Carbon, Green Growth', the details are too inadequate to content the requirements of modalities and procedures for CCS as CDM project. Therefore, it is required not only to amend the existing laws related with capture, transport, and storage of $CO_2$ for paving the way of an prompt deployment of CCS CDM activities in Korea as a short-term approach, but also to establish the united framework as a long-term approach.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.261-271
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• 2016

In the prediction of response of a pile in soil, numerical approaches such as a finite element method are generally applied due to complicate nonlinear behaviors of soils. However, the numerical methods based on the finite elements require heavy efforts in pile and soil modelling and also take long computing time. So their usage is limited especially in the early design stage in which principal dimensions and properties are not specified and tend to vary. On the contrary, theoretical approaches adopting linear approximations for soils are relatively simple and easy to model and take short computing time. Therefore, if they are validated to be reliable, they would be applicable in predicting responses of a pile in soil, particularly in early design stage. In case of wind turbines regarded in this study, it is required to assess their natural frequencies in early stages, and in this simulation the supporting pile inserted in soil could be replaced with a simplified elastic boundary condition at the bottom end of the wind turbine tower. To do this, analysis for a pile in soil is performed in this study to extract the spring constants at the top end of the pile. The pile in soil can be modelled as a beam on elastic spring by assuming that the soils deform within an elastic range. In this study, it is attempted to predict pile deformations and influence factors for lateral loads by means of the beam-on-spring model. As two example supporting structures for wind turbines, mono pile and suction pile models with different diameters are examined by evaluating their influence factors and validated by comparing them with those reported in literature. In addition, the deflection profiles along the depth and spring constants at the top end of the piles are compared to assess their supporting features.

• Journal of the Korean Magnetics Society
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• v.26 no.6
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• pp.219-225
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• 2016

In this study, for assessment of degenerative knee joint cartilage disease we acquired images by fat suppressed 3D spoiled gradient recalled (SPGR) and fat suppressed 3D $T2^*$ weighted imaging techniques. To do a quantitative evaluation, the knee joint cartilage was divided into medial femoral cartilage (MFC), medial tibial cartilage (MTC), lateral femoral cartilage (LFC), lateral femoral cartilage (LFC) and patella cartilage (Pat) to measure their respective signal intensity values, signal-to-noise ratio, and contrast-to-noise ratio. As for the measured values, statistical significance between two techniques was verified by using Mann-Whitney U-Test. To do a qualitative evaluation, two radiologists have examined images by techniques after which image artifact, cartilage surface, tissue contrast, and depiction of lesion distinguishing were evaluated based on 4-point scaling (1: bad, 2: appropriate, 3: good, 4: excellent), and based on the result, statistical significance was verified by using Kappa-value Test. 3.0T MR system and HD T/R 8ch knee array coil were used to acquire images. As a result of a quantitative analysis, based on SNR values measured by using two imaging techniques, MFC, LFC, LTC, and Pat showed statistical significance (p < 0.05), but MTC did not (p > 0.05). As a result of verifying statistical significance for measured CNR value, MFC, LFC, and Pat showed statistical significance (p < 0.05), while MTC and LTC did not show statistical significance (p > 0.05). As a result of a qualitative analysis, by comparing mean values for evaluated image items, 3D $T2^*$ weighted Image has indicated a slightly higher value. As for conformance verification between the two observers by using Kappa-value test, all evaluated items have indicated statistically significant results (p < 0.05). 3D $T2^*$ weighted technique holds a clinical value equal to or superior to 3D SPGR technique with respect to evaluating images, such as distinguishing knee joint cartilages, comparing nearby tissues contrast, and distinguishing lesions.

• Journal of the Korean Geotechnical Society
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• v.33 no.11
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• pp.21-34
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• 2017

The ground penetrating radar (GPR) signal can be measured with different amplitudes according to the directivity, so the directivity of the antenna should be considered. The objective of this study is to investigate the directivity of antenna by analyzing the reflection characteristics of electromagnetic waves radiated from the antenna, and to evaluate effective range of angle that can inspect an abnormal area according to the directivity of antenna. For the measurement of the directivity, a circular metal bar is used as reflector and the signals are measured by changing the angle and the distance between reflector and antenna in the E- and H-plane. The boundary distance between the near field and the far field is determined by analyzing the amplitudes of reflected signals, and two points with different distances from each of near and far fields are designated to analyze radiation patterns in near and far fields. As a result of radiation pattern measurement, in the near field, minor lobes are observed at angle section at more than $50^{\circ}$ in both E- and H-plane. Therefore, antenna has the directivity for the direction of main lobe and minor lobes in near field. In the far field, antenna has the directivity for a single direction of main lobe because minor lobes are not observed. The amplitude of the signal reflected from the near field is unstable, but it can be distinguished from noise. Therefore, in the near field, the ground anomaly can be detected with high reliability. On the other hand, the amplitude of the signal reflected from the far field is stable, but it is hard to distinguish between reflected signal and noise because of the excessive loss of electromagnetic wave. The analyses of directivity in the near and the far fields performed in this study may be effectively used to improve the reliability of the analyses of abnormal area.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.4
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• pp.291-298
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• 2007

Purpose: To investigate the feasibility of TI-201 SPECT with intra coronary injection (lC-I) in the detection of viable myocardium, we have performed SPECT imaging after direct intracoronary injection of TI-201 and images were compared with those of stress-reinjection (Re-I) SPECT. Methods: Fourteen coronary artery disease patients (male 11, mean age 54 years) who had myocardial infarction or demonstrated left ventricular wall motion abnormality on echocardiography were enrolled. Three mCi of TI-201 was injected into both coronary arteries during angiography and images were acquired between 6- and 24-hour after injection. Reinjection imaging with 1 mCi of TI-201 was performed at 4-hour after adenosine stress imaging with 3 mCi of TI-201. Images were interpreted according to 4-grade visual scoring system (grade 0-3). Segments with mild to moderated uptake (${\leq}$grade 1), and upgraded more than one score with reinjection, and were defined as viable myocardium. Results: Image quality was poor in two cases with IC-I. Numbers of non-viable segments were 60 (23.8%) with IC-I, and 38 (15.1%) with Re-I, respectively. Overall agreement for perfusion grade per myocardial segment in each IC-I and Re-I was 76.5%. Overall agreement for viable segment between IC-I and Re-I was 90.5%. Only one out of 38 segments interpreted as non-viable with Re-I were interpretated as viable with IC-I. And 23 out of 214 segments interpreted as viable with Re-I were interpreted as non-viable with IC-I. Conclusion: Intracoronary TI-201 SPECT seemed to be not advantageous over stress-rest reinjection imaging in the assessment of myocardial viability, mainly due to low count statistics at 6-hour or 24-hour delayed time points. The feasibility of intracoronary TI- 201 SPECT is considered to be limited.