• Proceedings of the KWS Conference
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• 2010.05a
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• pp.43-46
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• 2010

As the nuclear power plant has been constructed continuously for several decades in Korea, the welding technology for components manufacturing and installation has been improved largely. Standardization for weld test and qualification was also established systematically according to the concerned code. The welding for the main components requires the high reliability to keep the constant quality level, which means the repeatability of weld quality. Therefore the weld process qualified by thorough test and evaluation is able to be applied for manufacturing. Narrow gap SAW and GTAW process are usually applied for girth seam welding of pressure vessel like Reactor vessel, steam generator, and etc. For the surface cladding with stainless steel and Inconel material, strip welding process is mainly used. Inside cladding of nozzles is additionally applied with Hot wire GTAW and semi-auto welding process. Especially the weld joint having elliptical weld line on curved surface needs a specialized weld system which is automatically rotating with adjusting position of the head torch. The small sized pipe, tube, and internal parts of reactor vessel requests precise weld processes like an automatic GTAW and electron beam welding. Welding of dissimilar materials including Inconel690 material has high possibility of weld defects like a lack of fusion, various types of crack. To avoid these kinds of problem, optimum weld parameters and sequence should be set up through the many tests. As the life extension of nuclear power plant is general trend, weld technologies having higher reliability is required gradually. More development of specialized welding systems, weld part analysis and evaluation, and life prediction for main components should be taken into a consideration extensively.

• Steel and Composite Structures
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• v.16 no.6
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• pp.703-718
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• 2014

The initial clamping forces of high strength bolts subjected to different faying surface conditions drop within 500 hours regardless of loading, any other external force or loosening of the nut. This study develops a mathematical model for relaxation confined to creep on a coated faying surface after initial clamping. The quantitative model for estimating relaxation was derived from a regression analysis for the relation between the creep strain of the coated surface and the elapsed time for 744 hours. This study establishes an expected model for estimating the relaxation of bolted joints with diverse coated surfaces. The candidate bolts are dacro-coated tension control bolts, ASTM A490 bolt, and plain tension control bolts. The test parameters were coating thickness, species of coating. As for 96, 128, 168, and $226{\mu}m$ thick inorganic zinc, when the coating thickness was increased, relaxation after the initial clamping rose to a much higher range from 10% to 18% due to creep of the coating. The amount of relaxation up to 7 days exceeded 85% of the entire relaxation. From this result, the equation for creep strain can be derived from a statistical regression analysis. Based on the acquired creep behavior, it is expected that the clamping force reflecting relaxation after the elapse of constant time can be calculated from the initial clamping force. The manufacturer's recommendation of inorganic zinc on faying surface as $75{\mu}m$, appears to be reasonable.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3183-3186
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• 2013

Purpose: The 7th edition of the American Joint Committee on Cancer Staging Manual for esophageal cancer (EC) categorizes N stage according to the number of metastatic lymph nodes (LNs), irrespective of the site. The aim of this study was to determine the prognostic value of subcarinal LN metastasis in patients undergoing esophagectomy for esophageal squamous cell carcinoma (ESCC). Methods: A retrospective analysis of 507 consecutive patients with ESCC was conducted. Potential clinicopathological factors that could influence subcarinal LN metastasis were statistically analyzed. Univariate and multivariate analyses were also performed to evaluate the prognostic parameters for survival. Results: The frequency of subcarinal LN metastasis was 22.9% (116/507). Logistic regression analysis showed that tumor length (>3cm vs ${\leq}3cm$; P=0.027), tumor location (lower vs upper/middle; P=0.009), vessel involvement (Yes vs No; P=0.001) and depth of invasion (T3-4a vs T1-2; P=0.012) were associated with 2.085-, 1.810-, 2.535- and 2.201- fold increases, respectively, for risk of subcarinal LN metastasis. Multivariate analyses showed that differentiation (poor vs well/moderate; P=0.001), subcarinal LN metastasis (yes vs no; P=0.033), depth of invasion (T3-4a vs T1-2; P=0.014) and N staging (N1-3 vs N0; P=0.001) were independent prognostic factors. In addition, patients with subcarinal LN metastasis had a significantly lower 5-year cumulative survival rate than those without (26.7% vs 60.9%; P<0.001). Conclusions: Subcarinal LN metastasis is a predictive factor for long-term survival in patients with ESCC.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.311-322
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• 2009

Using the 3-D analysis, this study winpared and analyzed the 'fade-shot swing' which is one of the golf technique. The subjects of this study were 3 male pro golfers they experimented with only a 7 iron. The purpose was to enhance their performance by producing the important kinematical parameters, finding out the features in them and providing the data to a coach and players. As a result, the position of the club head showed from the outside orbit to the inside orbit. When position of the center of mass moved backwards, the probability of the failure of the fade-shot increased. Cocking angle had an effect on easing the wrist for a smooth follow-through after the impact. It showed that the changes in the shoulder movement was made first and followed by the waist. The hip joint angular velocity achieved a smooth fade-shot motion due to the hitting delay also the velocity of the club-head was faster when uncocking was released at the time of impact.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.1
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• pp.73-80
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• 2000

The stewart platform manipulator proposed by stewart is the parallel manipulator which is composed of several independent actuators connecting the upper plate with the base plate and capable of executing a six degree of freedom motion. The manipulator has a structure of a closed loop form, and provides better load-to-weight ratio and ratio and rigidity than a serial manipulator with an open loop form. Moreover, the manipulator has high positional accuracy because position errors of actuators are not additive. Because of these advantages, this manipulator is widely used in many engineering applications such as a driving simulator, a tool of machining center, a force/torque sensor and so on. When this Stewart platform manipulator is controlled in joint space, it is difficult to design a controller using an analytic method due to nonhnearity and unknown parameters of actuators. Therefore, a PID controller is often used because of easiness in applications. To find the PID control gain, a trial-and-error method is generally used. This method is time-consuming, and does not guarantee a optimal gain. Thus, this paper proposes a GA-PID controller which selects an optimal PID control gain using genetic algorithms. And this proposed controller is evaluated experimentally and shows acceptable performance.

• The Journal of the Acoustical Society of Korea
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• v.35 no.2
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• pp.134-142
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• 2016

In this paper, a method synthesizing speech signal using the 40 kHz ultrasonic signals reflected from the articulatory muscles was introduced and performance was evaluated. When the ultrasound signals are radiated to articulating face, the Doppler effects caused by movements of lips, jaw, and chin observed. The signals that have different frequencies from that of the transmitted signals are found in the received signals. These ADS (Acoustic-Doppler Signals) were used for estimating of the speech parameters in this study. Prior to synthesizing speech signal, a quantitative correlation analysis between ADS and speech signals was carried out on each frequency bin. According to the results, the feasibility of the ADS-based speech synthesis was validated. ADS-to-speech transformation was achieved by the joint Gaussian mixture model-based conversion rules. The experimental results from the 5 subjects showed that filter bank energy and LPC (Linear Predictive Coefficient) cepstrum coefficients are the optimal features for ADS, and speech, respectively. In the subjective evaluation where synthesized speech signals were obtained using the excitation sources extracted from original speech signals, it was confirmed that the ADS-to-speech conversion method yielded 72.2 % average recognition rates.

• Smart Structures and Systems
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• v.13 no.2
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• pp.257-280
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• 2014

In this paper, a novel PARAllel FACtor (PARAFAC) decomposition based Blind Source Separation (BSS) algorithm is proposed for modal identification of structures equipped with tuned mass dampers. Tuned mass dampers (TMDs) are extremely effective vibration absorbers in tall flexible structures, but prone to get de-tuned due to accidental changes in structural properties, alteration in operating conditions, and incorrect design forecasts. Presence of closely spaced modes in structures coupled with TMDs renders output-only modal identification difficult. Over the last decade, second-order BSS algorithms have shown significant promise in the area of ambient modal identification. These methods employ joint diagonalization of covariance matrices of measurements to estimate the mixing matrix (mode shape coefficients) and sources (modal responses). Recently, PARAFAC BSS model has evolved as a powerful multi-linear algebra tool for decomposing an $n^{th}$ order tensor into a number of rank-1 tensors. This method is utilized in the context of modal identification in the present study. Covariance matrices of measurements at several lags are used to form a $3^{rd}$ order tensor and then PARAFAC decomposition is employed to obtain the desired number of components, comprising of modal responses and the mixing matrix. The strong uniqueness properties of PARAFAC models enable direct source separation with fine spectral resolution even in cases where the number of sensor observations is less compared to the number of target modes, i.e., the underdetermined case. This capability is exploited to separate closely spaced modes of the TMDs using partial measurements, and subsequently to estimate modal parameters. The proposed method is validated using extensive numerical studies comprising of multi-degree-of-freedom simulation models equipped with TMDs, as well as with an experimental set-up.

• The Journal of the Korean bone and joint tumor society
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• v.20 no.2
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• pp.66-73
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• 2014

Purpose: Various diagnostic imaging modalities have been used to evaluate the effect of neoadjuvant chemotherapy for osteosarcoma early and noninvasively. We evaluated the effectiveness of imaging studies of plain radiographs and positron-emission tomography/computed tomography (PET/CT) in predicting neoadjuvant chemotherapy effect for osteosarcoma and tried to establish a general principle in interpretation of PET/CT parameters. Materials and Methods: Eighteen patients who underwent two cycles of neoadjuvant chemotherapy and surgical excision for osteosarcoma were enrolled. There were 13 males and 5 females, with a median age of 19 (11-63) years. Fifteen patients of 18 had the American Joint Committe on Cancer (AJCC) stage IIB. They had plain radiographs and PET/CT before and after neoadjuvant chemotherapy. The resected tumor specimens were pathologically examined to determine histological response grade using a conventional mapping method. Statistical analysis was performed to evaluate the correlation between histopathological necrosis rate, and radiographic finding category, post-chemotherapy maximum standardized uptake value (SUVmax), average standardized uptake value and metabolic tumor volume (MTV) as well as reduction rates of them. Results: Eight patients were good responders to neoadjuvant chemotherapy based on histological evaluation. Median SUVmax reduction rate was 73 (23-77) % in good responders and 42 (-32-76) % in poor responders. Median MTV reduction rate was 93.5 (62-99) % in good responders and 46 (-81-100) % in poor responders. While radiographic finding category was not different according to histological response (p=1.0), SUVmax reduction rate was significantly different (p=0.041). Difference in MTV reduction rates approached statistical significance as well (p=0.071). Conclusion: While radiographic finding category was not reliable to assess neoadjuvant chemotherapy effect for osteosarcoma, reduction rate of SUVmax was a useful indicator in this study. As parameters of PET/CT can be influenced by various factors of settings, different centers have to make an effort to establish their own standard of judgement with reference of previous studies.

• The Journal of the Acoustical Society of Korea
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• v.34 no.6
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• pp.423-431
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• 2015

KIOST-HYU joint acoustics experiment was performed on the western shallow water off the Taean peninsula in the Yellow Sea in May 2013. In this paper, mid-frequency (6~16 kHz) bottom loss data measured in a grazing angle range of $17{\sim}60^{\circ}$ are presented and compared to the predictions obtained using a Rayleigh reflection model. The sediment structure of the experimental site was characterized by multi-layered sediment and the components of the surficial sediment consisted of various types of particles with a mean grain size of $5.9{\phi}$. The model predictions obtained using the mean grain size were not in agreement with the measured bottom loss, and those obtained using the grain size of $4{\phi}$, which was estimated by an inversion process, showed a best fit to the measurements. It would be because the standard deviation of the gain-size distribution of surficial sediment is $4.3{\phi}$, which is much larger than those of other areas around the experimental site. Finally, the model predictions obtained using the geoacoustic parameters estimated from the inversion process for the surficial sediment layer and those corresponding to the mean grain size of $1.3{\phi}$ for lower layer are reasonably agreement with the measured bottom loss data.

• IMMUNE NETWORK
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• v.1 no.3
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• pp.244-249
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• 2001

The transforming growth $factor-{\beta}$ ($TGF-{\beta}$) is a multifunctional cytokine modulating the onset and course of autoimmune disease as shown in experimental models. In synovial inflammation, there is a potential role for $TGF-{\beta}$ in repairment, the inhibition of cartilage and bone destruction, and the down-regulation of immune response. The biologic effects of $TGF-{\beta}$ depend on the cell type, the isoform and the availability of active $TGF-{\beta}$. We investigated $TGF-{\beta}$ expression in patients with rheumatoid arthritis (RA) and compared to those of osteoarthritis (OA). And we determined a correlation between $TGF-{\beta}1$ and $TGF-{\beta}2$, and also the relationships between each $TGF-{\beta}$ isoform and the parameters for disease activity of RA. Methods: The study population consisted of 20 patients with RA and 20 patients with OA. The commercial ELISA kit was used to study $TGF-{\beta}1$ and $TGF-{\beta}2$ levels in peripheral blood (PB) and synovial fluids (SF). Results: 1) While PB $TGF-{\beta}1$ level was of no difference between RA and OA patient groups, SF $TGF-{\beta}1$ level was higher in RA group than OA group. Similarly, PB $TGF-{\beta}2$ levels of RA and OA groups was not different, but SF $TGF-{\beta}2$ levels was higher in RA group than OA group. 2) In patients with RA, the $TGF-{\beta}1$ levels were higher than $TGF-{\beta}2$ in both the PB and SF, while in patients with OA, there showed higher readings for $TGF-{\beta}1$ than $TGF-{\beta}2$ in SF but no difference between $TGF-{\beta}1$ and $TGF-{\beta}2$ levels in PB. 3) In patients with RA, there were no correlations between PB $TGF-{\beta}1$ and PB $TGF-{\beta}2$ levels, nor between SF $TGF-{\beta}1$ and SF $TGF-{\beta}2$ levels. At the same way, there was no correlation between PB $TGF-{\beta}1$ and SF $TGF-{\beta}1$ levels, nor between each levels of $TGF-{\beta}2$ in patients with RA. 4) There was also no correlation between each $TGF-{\beta}$ isoform and the parameters for disease activity such as ESR, CRP, tender joint count, swollen joint count, rheumatoid factor, and the duration of morning stiffness except between in PB $TGF-{\beta}1$ and disease duration of RA (r=0.637, p<0.01). Conclusion: Each $TGF-{\beta}$ isoforms were higher in synovial fluid of patients with RA than that of patients with OA. The data from the RA patients demonstrated different patterns of expressions of the isoforms depending on which compartment (PB or SF) was investigated. The quantification of different $TGF-{\beta}$ isoform is thought to be important when $TGF-{\beta}$ is measured under disease conditions of RA.