• Advances in nano research
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• v.17 no.1
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• pp.33-49
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• 2024

Using the mechanical treatments for mechanical properties improvement was rarely in the development scope before. This research approves through analytical ways that surface impacts can improve the quality of the surface significantly. This fact is approved for deposited titanium on silicone substrate. The new algorithm called minimum resultant error method (MREM) which is a direct combination of nanoindentation, FEM and dimensional analysis through a reverse method is utilized to extract the mechanical characteristics of the coating surface before and after impact. This method is extended to the time dependent behavior of the material to obtain strain rate coefficient. To implement this new approach, a new analysis technic is developed to define the residual stress field caused by surface impact as initial condition for nanoindentation. Analyzing the model in micro and macro scale at the same time was one of the main resolved challenges in this study. The result was obtaining of the constants of Johnson-Cook constitutive equation. Comparing the characteristics of the coating surface before and after impact shows high improvement in yield stress (34%), Elastic modulus (7.75%) and strain hardening coefficient (2.8%). The main achievement is that the strength improvement in titanium thin layer is much higher than bulk titanium. The yield strength shows 41.7% improvement for coated titanium comparing with 24% for bulk material. The rate of enhancement is about 6 times when it comes to the Young's modulus.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.28 no.3
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• pp.271-282
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• 2024

The history of liver surgery is a tale of progressive resolution of issues presenting one after another from ancient times to the present days when dealing with liver ailments. The perfect knowledge of human liver anatomy and physiology and the development of a proper liver resective surgery require time and huge efforts and, mostly, the study and research of giants of their own times, whose names are forever associated with anatomical landmarks, thorough descriptions, and surgical approaches. The control of parenchymal bleeding after trauma and during resection is the second issue that surgeons have to resolve. A good knowledge of intra and extrahepatic vascular anatomy is a necessary condition to develop techniques of vascular control, paving the way to liver transplantation. Last but not least, the issue of residual liver function after resection requires advanced techniques of volume redistribution through redirection of blood inflow. These are the same problems any young surgeon would face when approaching liver surgery for the first time. Therefore, obtaining a wide picture of historical evolution of liver surgery could be a great starting point to serve as an example and a guide.

• Journal of Practical Engineering Education
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• v.16 no.5_spc
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• pp.611-618
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• 2024

The rapid advancement of deep learning has significantly enhanced the performance of single image super-resolution (SR). However, most existing deep learning-based image SR networks only facilitate information flow in the forward direction, which limits their performance. In this study, we investigate a feedback network for precise image SR. This feedback network effectively enhances lower-level feature representation by rerouting multiple higher-level features. We sequentially construct several Residual Density Modules and deploy them repeatedly over time. Multiple feedback connections between two adjacent time steps leverage high-level features captured within a large receptive field to refine low-level features lacking sufficient contextual information. A carefully designed feedback module efficiently selects and enhances valuable information from the rerouted high-level features, thereby improving low-level features with enriched high-level information. Extensive experiments demonstrate that the proposed method outperforms existing approaches in both objective and subjective evaluations.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.5
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• pp.832-836
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• 1994

This study was carried out to investigate several kinds of characteristics of pork sausage prepared by different cooking temperature and time (60, 90, 120, 150, 180 minutes in $58^{\circ}C$ and 25, 40, 55, 70, 85 minutes in $65^{\circ}C$). In case of color, L(bright), a (red) and b(yellow) value were 64.60-65.26, 9.14-9.94 and 8.68-9.34 in $58^{\circ}C$, and 65.16-66.68, 8.78-9.62 and 7.66-8.36 in $63^{\circ}C$, respectively. Gel strength showed high when cooking time was 120, 250 and 180 minute in $58^{\circ}C$ and 40 minute in $65^{\circ}C$. Residual nitrite concentration showed higher $58^{\circ}C$ than $65^{\circ}C$ and decreased gradually as cooking time elevated in all cooking temperature. Total plate count in 58$^{\circ}C$ was higher than $65^{\circ}C$, was wholly $8.7{\times}10^2~3.5{\times}10^3$.In case of free amino acid content, Asp, Glu and Lys were high and Cys, Met and Tyr low and was not different with $58^{\circ}C$ and $65^{\circ}C$. The result of sensory evaluation was not different (p<0.05) with $58^{\circ}C\;and\;65^{\circ}C$.

• The Korean Journal of Financial Management
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• v.24 no.3
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• pp.63-89
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• 2007

This study aims at empirically verifying whether long memory properties exist in returns and volatility of the financial time series and then, empirically observing influential factors of long-memory properties. The presence of long memory properties in the financial time series is examined with the Hurst exponent. The Hurst exponent is measured by DFA(detrended fluctuation analysis). The empirical results are summarized as follows. First, the presence of significant long memory properties is not identified in return time series. But, in volatility time series, as the Hurst exponent has the high value on average, a strong presence of long memory properties is observed. Then, according to the results empirically confirming influential factors of long memory properties, as the Hurst exponent measured with volatility of residual returns filtered by GARCH(1, 1) model reflecting properties of volatility clustering has the level of $H{\approx}0.5$ on average, long memory properties presented in the data before filtering are no longer observed. That is, we positively find out that the observed long memory properties are considerably due to volatility clustering effect.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.433-433
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• 2012

As the requirement in patterning geometry continuously shrinks down, the termination of etch process at the exact time became crucial for the success in nano patterning technology. By virtue of real-time optical emission spectroscopy (OES), etch end point detection (EPD) technique continuously develops; however, it also faced with difficulty in low open ratio etching, typically in self aligned contact (SAC) and one cylinder contact (OCS), because of very small amount of optical emission from by-product gas species in the bulk plasma glow discharge. In developing etching process, one may observe that coupon test is being performed. It consumes costs and time for preparing the patterned sample wafers every test in priority, so the coupon wafer test instead of the whole patterned wafer is beneficial for testing and developing etch process condition. We also can observe that etch open area is varied with the number of coupons on a dummy wafer. However, this can be a misleading in OES study. If the coupon wafer test are monitored using OES, we can conjecture the endpoint by experienced method, but considering by data, the materials for residual area by being etched open area are needed to consider. In this research, we compare and analysis the OES data for coupon wafer test results for monitoring about the conditions that the areas except the patterns on the coupon wafers for real-time process monitoring. In this research, we compared two cases, first one is etching the coupon wafers attached on the carrier wafer that is covered by the photoresist, and other case is etching the coupon wafers on the chuck. For comparing the emission intensity, we chose the four chemical species (SiF2, N2, CO, CN), and for comparing the etched profile, measured by scanning electron microscope (SEM). In addition, we adopted the Dynamic Time Warping (DTW) algorithm for analyzing the chose OES data patterns, and analysis the covariance and coefficient for statistical method. After the result, coupon wafers are over-etched for without carrier wafer groups, while with carrier wafer groups are under-etched. And the CN emission intensity has significant difference compare with OES raw data. Based on these results, it necessary to reasonable analysis of the OES data to adopt the pre-data processing and algorithms, and the result will influence the reliability for relation of coupon wafer test and whole wafer test.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.51-56
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• 2008

The waveform inversion for isotropic media has ever been studied since the 1980s, but there has been few studies for anisotropic media. We present a seismic waveform inversion algorithm for 2-D heterogeneous transversely isotropic structures. A cell-based finite difference algorithm for anisotropic media in time domain is adopted. The steepest descent during the non-linear iterative inversion approach is obtained by backpropagating residual errors using a reverse time migration technique. For scaling the gradient of a misfit function, we use the pseudo Hessian matrix which is assumed to neglect the zero-lag auto-correlation terms of impulse responses in the approximate Hessian matrix of the Gauss-Newton method. We demonstrate the use of these waveform inversion algorithm by applying them to a two layer model and the anisotropic Marmousi model data. With numerical examples, we show that it's difficult to converge to the true model when we assumed that anisotropic media are isotropic. Therefore, it is expected that our waveform inversion algorithm for anisotropic media is adequate to interpret real seismic exploration data.

• Journal of the Korean Applied Science and Technology
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• v.38 no.2
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• pp.543-550
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• 2021

The purpose of this study was to verify the mediating effect of the change of grit in the relationship that the change of exercise time of adolescents leads to the change of self-esteem. The data of 2,438 students (male = 1,327, female = 1,111) were used for the analysis, excluding cases including missing values in the data from the wave 1 and wave 2 of the Korean Children and Youth Panel 2018. The standardized residual score generated through regression analysis from the values in wave 1 to the values in wave 2 was used as a variable for the amount of change. As a results, the correlation between the amount of change in all three variables was found to be significant. Result of the hierarchical regression analysis revealed that it was confirmed that the partial mediating effect that the change of exercise time directly or indirectly affects the change of self-esteem through the change of grit is significant. These results indicate that adolescents, exercise time is gradually decreasing as the grade goes up, and this has an effect on the reduction of grit and self-esteem.

• Journal of Chest Surgery
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• v.43 no.4
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• pp.404-408
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• 2010

Background: Pleural symphysis is regarded as an important treatment option in reducing recurrence rates after surgical treatment of spontaneous pneumothorax. However, there is much debate over the best method for achieving pleural symphysis. We retrospectively compared apical pleurectomy (AP) with mechanical pleural abrasion (MPA). Material and Method: Between January 2000 and December 2007, 83 patients underwent video-assisted thoracoscopic surgery (VATS) for spontaneous pneumothorax. In addition to wedge resection of bullae, MPA was performed in 21 patients (group A) and AP in 62 patients (group B). Result: There were no significant differences in age, gender and site of pneumothorax between the two groups. Operative time was $97{\pm}44$ minutes in group A and $77{\pm}18$ minutes in group B (p>0.05). The mean amount of pleural drainage through the chest tube on the first postoperative day was $156{\pm}87 cc$ in group A and $147{\pm}87 cc$ in group B (p>0.05). There was no mortality or significant morbidity in all patients with the exception of reoperation for bleeding in two patients in group B. In the postoperative course, there were no statistical differences between the two groups in the rate of residual air space, air leak and indwelling time of chest tube, and hospital stay. Mean follow up time was $31.7{\pm}25.3$ months, and the recurrence rate of pneumothorax was 9.5% (2/21) in group A and 6.5% (4/62) in group B, without statistical significance. Conclusion: AP was no more advantageous than MPA in terms of operative time, postoperative course and prevention of recurrent pneumothorax. Therefore, complete resection of bullae and existence of residual bullae are more important factors in reducing the incidence of recurrent pneumothorax than pleural symphysis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.1
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• pp.98-104
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• 1999

To investigate the relationships between ocean environmental characteristics, the time-series data of temperature and salinity observed at a station near at Hanlim set net in 1995 and 1996 are analyzed, and the results are as follow ; 1. In hanlim set net, the diurnal range of temperature and salinity variation in summer is very large and the amplitude of short-period fluctuation of temperature and salinity is very large. That is, not only the water of the middle and bottom layers (low temperature and high salinity) but also the coalstal water (high temperature and low salinity) appears alternatively depending on the current direction 2. from the result of mooring for 22 days in Hanlim set net, the mean speed and direction of tidal current in neap tide were 9.1 cm/sec and south westward in ebb time, and 11.6 cm/sec and north or northeastward in flood time, respectively. The highest speed of the current was 15cm/sec in ebb time, and 22.6 cm/sec in flood time. The mean speed and direction of tidal current in spring tide were 10.4 cm/sec, and southwestward in ebb time, and 12.3 cm/sec, and north or northestward in flood time, respectively. The highest speed of the current was 19.4 cm/sec in ebb time, and 20 cm/sec in flood time respectively. The mean speed of the current in flood time was larger than that in ebb time. The velocity vector along the major axis of semidiurnal tide ($M_2$) component was 1.5 times larger than that of diurnal tide ($K_1$), The major directions of two compornants were northwestward and east-southeastward and residiual current were 3.25 cm/sec and northwestward-directed. Result of TGPS Buoy tracer for 3 days between Biyang-Do and Chgui-Do showed that the mean speed was 1.6 knot in ebb time and 1.3 knot in flood time. Direction of tidal was southwestward in ebb time and northeastward in flood time respectively. The maximum current speed was 4.8 knot in ebb time and 3.7 knot in flood time respectively. The mean speed and direction of tidal in of offshore were 1.7 knot and northwestward in flood time. The residual current appeared 0.3 knot northeastward.