• Journal of the Korean Mathematical Society
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• v.59 no.2
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• pp.217-233
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• 2022

Although machine learning shows state-of-the-art performance in a variety of fields, it is short a theoretical understanding of how machine learning works. Recently, theoretical approaches are actively being studied, and there are results for one of them, margin and its distribution. In this paper, especially we focused on the role of margin in the perturbations of inputs and parameters. We show a generalization bound for two cases, a linear model for binary classification and neural networks for multi-classification, when the inputs have normal distributed random noises. The additional generalization term caused by random noises is related to margin and exponentially inversely proportional to the noise level for binary classification. And in neural networks, the additional generalization term depends on (input dimension) × (norms of input and weights). For these results, we used the PAC-Bayesian framework. This paper is considering random noises and margin together, and it will be helpful to a better understanding of model sensitivity and the construction of robust generalization.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.48 no.5
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• pp.249-258
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• 2022

The specific muscular structure of the tongue greatly affects margin shrinkage and tumor invasion, making the optimal surgical margin controversial. This study investigated surgical margin correlated prognosis of TSCC (tongue squamous cell carcinoma) according to margin location and its value, and the histopathologic factors which are suggestive of tumor invasion. And we would like to propose defining of the surgical margin for TSCC via prognosis according to location and margin values. We reviewed 45 patients diagnosed with TSCC who visited Seoul National University Dental Hospital (SNUDH) (Seoul, Republic of Korea) from 2010 to 2019, who were managed by a single surgical team. Patient clinical and pathological data of patients were retrospectively reviewed, and in 36 out of 45 patients, the pathologic parameters including the worst pattern of invasion (WPOI) and tumor budding were investigated via diagnostic histopathology slide reading. When standardized with as 0.25 cm anterior margins, as 0.35 cm deep margin, there was no significant difference in disease specific survival (DSS) or loco-regional recurrence-free survival (LRFS). Additionally, there was a non-significant difference in DSS and LRFS at the nearest margin of 0.35 cm (P_DSS=0.276, P_LRFS=0.162). Aggressive WPOI and high tumor budding showed lower survival and recurrence-free survival, and there were significant differences in close margin and involved margin frequencies. In TSCC, the value and location of the surgical margin did not have a significant relationship with prognosis, but WPOI and tumor budding suggesting the pattern of muscle invasion affected survival and recurrence-free survival. WPOI and tumor budding should be considered when setting an optimal surgical margin.

• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.17-21
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• 2009

This experimental study was to determine the fitness on each cervical margin of recast using crown base metal alloy. The alloy used in this experimental study was a Ni-Cr alloy(Wirolloy, Bego, Germany) for the fabrication of full cast crown prosthesis. Twenty-five copings were divided into the five groups. And the group A, B, C, D and E were cording successively according to the frequency of recast to five times. Each specimen was recasted without adding new metal. The experimental results were as follows: 1. The group A and B showed good fitness had subtle differences in each cervical margin adaptation, in other words, the mesio and disto cervical margin showed worse adaptation than the bucco and linguo cervical margin. 2. The group C got good fitness in bucco and linguo cervical margins, but the mesio and disto cervical margin showed inaccurate fitness. And I could not get good casting bodies without adding new metal. 3. The group D and E showed bad fitness for each cervical margin. Therefore the group D and E lost its function as a dental restoration.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1934-1941
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• 2006

As the operating time of heat exchangers progresses, fouling caused by water-borne deposits and the number of plugged tubes increase and thermal performance decreases. Both fouling and tube plugging are known to interfere with normal flow characteristics and to reduce thermal efficiencies of heat exchangers. The heat exchangers of Korean nuclear power plants have been analyzed in terms of heat transfer rate and overall heat transfer coefficient as a means of heat exchanger management. Except for fouling resulting from the operation of heat exchangers, all the tubes of heat exchangers have been replaced when the number of plugged tubes exceeded the plugging criteria based on design performance sheet. This paper describes a plugging margin evaluation method taking into account the fouling of shell-and-tube heat exchangers. The method can evaluate thermal performance, estimate future fouling variation, and consider current fouling level in the calculation of plugging margin. To identify the effectiveness of the developed method, fouling and plugging margin evaluations were performed at a component cooling heat exchanger in a Korean nuclear power plant.

• Journal of Periodontal and Implant Science
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• v.51 no.3
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• pp.189-198
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• 2021

Purpose: This study was conducted to determine how the distance of the near insertion points in a vertical mattress suture from the wound margin influences the pattern of primary closure in an in vitro experimental model. Methods: Pairs of 180 porcine gingival and alveolar mucosa samples were harvested from 90 pig jaws and fixed to a specially designed model. A vertical mattress suture was performed with the near insertion point at 3 different distances from the wound margin (1-, 3-, and 5-mm) on both the gingival and mucosal samples (6 groups; n=30 for each group). The margin discrepancy and the presence of epithelium between the wound margins were measured on histologic slides. Results: The margin discrepancy decreased significantly as the near insertion point became closer to the wound margin both in mucosal tissue (0.241±0.169 mm, 0.945±0.497 mm, and 1.306±0.773 mm for the 1-, 3-, and 5-mm groups, respectively) and in gingival tissue (0.373±0.304 mm, 0.698±0.431 mm, and 0.713±0.691 mm, respectively). The frequency of complications of wound margin adaptation reduced as the distance of the near insertion point from the wound margin decreased both in the mucosal and gingival tissues. Conclusions: Placing the near insertion point close to the wound margin enhances the precision of wound margin approximation/adaptation using a vertical mattress suture.

• Journal of Labour Economics
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• v.39 no.2
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• pp.35-51
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• 2016

Using the Korea Labor and Income Panel Study (KLIPS) from 2000 to 2008, we estimate the Frisch elasticity of labor supply. Our point estimates of the intensive margin elasticity are around 0.23. The estimates are not sensitive to changes in household income and assets as well as changes in workweek regulation during the sample period that workers shall work for 5 days per week from Monday to Friday. We also estimate the extensive margin elasticity by considering labor market participation. We find that the point estimates at the extensive margin are greater than those at the intensive margin, but not statistically significant.

• Journal of Technologic Dentistry
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• v.32 no.1
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• pp.17-21
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• 2010

This experimental study was to determine the fitness in each cervical margin of reusing porcelain gold alloy. The gold alloy used in this experimental study was a Au-Pt-Pd alloy (BDCG-898, Bukwang Inc, Korea) for the fabrication of porcelain fused to metal crown. Twenty-five copings were divided into the five groups. And the group A, B, C, D and E were cording successively according to the frequency of reuse to five times. Each specimen was reused without adding new metal. The experimental results were as follows: 1. The group A, B, C showed good fitness in each cervical margin. 2. The group D got good fitness in labio and linguo cervical margin, but the mesio and disto cervical margin showed more than $40{\mu}m$ 3. The group E showed worse fitness than the other groups in each cervical margin.

• The KSFM Journal of Fluid Machinery
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• v.11 no.2
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• pp.38-45
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• 2008

This study presents a numerical procedure to optimize the compressor design to increase the surge margin of compressor with response surface method (RSM). The Box-Behnken design method is used to reduce the number of calculation for fitting the second-order response surface. In order to consider the increase of surge margin during numerical optimization without any calculation at the surge point, the slope of compressor characteristic curve at the design point is suggested as an objective function in the present optimization problem. Mean line performance analysis method is used to get the design and off-design characteristic curves of centrifugal compressor. The impeller exit angle, impeller exit height and impeller radius are chosen as design variables. The optimum shapes show the increase of surge margin for the surge margin optimization and increase of efficiency for the efficiency optimization in comparison with an initial shape.

• The Journal of Fisheries Business Administration
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• v.35 no.1
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• pp.169-191
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• 2004

This Study attempts to analysis the degrees of the efficiency of fisheries marketing channel's effectiveness, which are traditional marketing channel's effectiveness of fisheries wholesale markets and Discount Store's effectiveness such as margin, marketing performance. The study methodologies include not only a field sample survey but also a field interview. The results of this study are summarized as follows. First, at the numbers of fisheries marketing channel's margin factors, traditional marketing channel's margin factors are more than discount store's margin factors. Secondly, at the comparative study result of marketing channel margin efficiency, traditional marketing channel's prices are similar to discount store's prices. That is, consumers have bought similar retail price's seafood products through traditional marketing channels as well as discount stores cannels. Finally, however most consumers prefer discount stores to traditional retail stores because of discount store's multi-functions such as assortment of goods, freshness, exchange, refund and employee's kindness. In conclusion, the most important factor of fisheries marketing management is to realize the appropriate balance between marketing margin and consumer satisfaction.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.1
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• pp.1-17
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• 2023

Purpose. The purpose of this study was to examine the correlation between the finish line designs and the marginal adaptation of nonprecious metal alloy coping produced by different digital manufacturing methods. Materials and methods. Nonprecious metal alloy copings were made respectively from each master model with three different methods; SLS, milling and casting by computer aided design and computer aided manufacturing (CAD-CAM). Twelve copings were made by each method resulting in 72 copings in total. The measurement was conducted at 40 determined reference points along the circumferential margin with the confocal laser scanning microscope at magnification ×150. Results. Mean values of marginal gap of laser sintered copings were 11.8 ± 7.4 ㎛ for deep chamfer margin and 6.3 ± 3.5 ㎛ for rounded shoulder margin and the difference between them was statistically significant (P < .0001). Mean values of marginal gap of casted copings were 18.8 ± 20.2 ㎛ for deep chamfer margin and 33 ± 20.5 ㎛ for rounded shoulder margin and the difference between them was significant (P = .0004). Conclusion. Within the limitation of this study, the following conclusions were drawn. 1. The variation of finish line design influences the marginal adaptation of laser sintered metal coping and casted metal coping. 2. Laser sintered copings with rounded shoulder margin had better marginal fit than deep chamfer margin. 3. Casted copings with deep chamfer margin had better marginal fit than rounded shoulder margin. 4. According to the manufacturing method, SLS system showed the best marginal fit among three different methods. Casting and milling method followed that in order.