• Journal of the Korean Society for Precision Engineering
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• v.16 no.7
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• pp.210-218
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• 1999

Sheet deposition type rapid prototyping system have many advantages : high build speed, low operating cost, large part size, no phase change, no need for support generation, and forth. However, those sheet deposition type rapid prototyping system require an additional post processing to remove excessive material attached to the part. This post processing is time consuming and labor intensive. Moreover, it is difficult for those system to fabricate parts with hollow cores and internal cavities. A new sheet deposition type rapid prototyping system that minimizes the post processing is proposed. The proposed system automatically removes excessive material in a peeling-off process between two cutting processes. In this way, the proposed system can reduce the post-processing time and cost as well as the limitation of the feasible geometric shapes in the conventional sheet deposition system.

• Applied Microscopy
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• v.42 no.4
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• pp.212-217
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• 2012

This paper reports the effects of post-annealing of ZnO thin films on their microstructure and the device performance of the transistors fabricated from the films. From X-ray diffraction and transmission electron microscopy characterization, we uncovered that the grain size increased with the annealing temperature escalating and that the film stress shifted from compressive to tensile due to the grain size increment. Electrical characterization revealed that the grain size increase damaged the device performance by drastically lifting the off-current level. By annealing the devices in an $O_2$ ambient (instead of air), we were able to suppress the off-current while improving the electron mobility.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.13-17
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• 2015

Oxytetracycline (OTC) has been widely used in aquaculture field as a therapeutic and prophylactic agent because of its broad-spectrum activity against gram-positive and negative bacteria. Residual oxytetracycline (OTC) was studied after spray treatment of cultured abalone, Haliotis discus hannai. Muscle concentration of OTC was determined after spray treatment ( 4,000, 7,000, 10,000 ppm) in the abalone. Muscle samples were taken at 0, 1, 3, 7, 14, 21 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330 and 360 day post-dose. OTC analyses were carried out by high performance liquid chromatography (HPLC). In 4000, 7000 and 1000 ppm treatment for small size abalones, OTC levels at 1 day post-dose, have been dramatically decreased by 8.34, 3.35 and 4.47 ug/g, respectively. For medium size abalones, concentration were measured as 7.58, 15.62 and 7.8 ug/g, respectively. Those of large size abalones also were observed as 11.31, 12.38 and 15.28 ug/g, respectively, at 1 day post-dose. No significant differences in residual OTC depletion in muscles were observed between the size of abalones. More than 0.2 mg/kg of OTC was detected in muscle tissues and the residues were found over 60 days after treatment. It is expected that these results would contribute to improve recommended withdrawl periods of OTC for a safer seafood supply.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.407-414
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• 2014

The aim of the present study was to carry out quantitative analysis of spatial resolution for the influence of the focus size and digital image post-processing on the Computed Radiography (CR). The modulation transfer functions of an edge measuring method (MTF) was used for the evaluation of the spatial resolution. The focus size of X-ray tube was used the small focus (0.6 mm) and the large focus (1.2 mm). We evaluated the 50% and 10% of MTF for the enhancement of edge and contrast by using multi-scale image contrast amplification (MUSICA) in digital image post-processing. As a results, the edge enhancement than the contrast enhancement were significantly higher the spatial resolution of MTF 50% in all focus. Also the spatial resolution of the obtained images in a large focus were improved by digital image processing. In conclusion, the results of this study should serve as a basic data for obtain the high resolution clinical images, such as skeletal and chest images on the CR.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.8
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• pp.365-373
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• 2021

Loan monitoring is a fundamental element of credit control. The importance of loan monitoring is to reduce loan defaults and to increase loan repayment performance. The ex-post monitoring can also increase the loan quality and thus a concern to many creditors in the market economy. This study identifies the role of ex-post monitoring on loan repayment performance in the context of rural Vietnam. Employing primary data from rural areas of Vietnam, this study investigates the impacts of ex-post monitoring on loan repayment performance of individual borrowers in terms of on-time loan repayment and the rate of loan repayment. Descriptions of borrower demographics, loan information, and ex-post monitoring show the initial picture of borrowers and loans in Vietnam's rural areas. Quantitative estimations that use the Probit and the Tobit model confirm the argument that better ex-post monitoring would result in better loan repayment performance in both on-time repayment and repayment rate. Thus, some policy suggestions have been made to improve the monitoring system in each financial institution. The study also indicates that some other factors too affect loan repayment performance such as borrower's characteristics (education, agricultural working area, and income) as well as loan's characteristics (loan size, maturity, and loan purpose).

• Geomechanics and Engineering
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• v.28 no.5
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• pp.463-475
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• 2022

In the mine exploitation stage; one of the critical issues is the stability assessment of post-pillars. The instability of post-pillars leads to serious safety hazards in mining operations. The focus of this study is to assess the stability of post-pillars in the 130# stope in the central ore body at Trepça hard rock mine by employing both conventional (i.e., critical span curve) and numerical methods (i.e., FLAC3D). Moreover, a new numerical based index (i.e., Pillar Yield Ratio-PYR) was proposed. The aim of PYR index is to determine a border line between stable, potentially unstable, and failure state of post-pillars at a specific mine site. The critical value of pillar width to height ratio is 2.5 for deep production stopes (e.g., > 800 m). Results showed that pillar size, mining height and mining depth significantly have affected the post-pillar stability. The reliability of numerical based index (i.e., PYR) is verified based on empirical underground pillar stability graph developed by Lunder, 1994. The proposed pillar yield ratio index and pillar stability graph can be used as a design tool in new mining areas at Trepça hard rock mine and for other situations with similar geotechnical conditions.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.809-817
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• 2012

One of the OSI 7 Layer DDoS Attack, HTTP POST DDoS can deny legitimate service by web server resource depletion. This Attack can be executed with less network traffic and legitimate TCP connections. Therefore, It is difficult to distinguish DDoS traffic from legitimate users. In this paper, I propose an anomaly HTTP POST traffic detection algorithm and http each page Content-Length field size limit with defense method for HTTP POST DDoS attack. Proposed method showed the result of detection and countermeasure without false negative and positive to use the r-u-dead-yet of HTTP POST DDoS attack tool and the self-developed attack tool.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.27 no.3
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• pp.258-263
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• 2023

Backgrounds/Aims: Hemangiomas are the most common benign liver lesions; however, they are usually asymptomatic and seldom require surgery. Enucleation and resection are the most commonly performed surgical procedures for symptomatic lesions. This study aims to compare the outcomes of these two surgical techniques. Methods: A retrospective analysis of symptomatic hepatic hemangiomas (HH) operated upon between 2000 and 2021. Patients were categorized into the enucleation and resection groups. Demographic profile, intraoperative bleeding, and morbidity (Clavien-Dindo Grade) were compared. Independent t-test and chi-square tests were used for continuous and categorical variables respectively. p-value of < 0.05 was considered significant. Results: Sixteen symptomatic HH patients aged 30 to 66 years underwent surgery (enucleation = 8, resection = 8) and majority were females (n = 10 [62.5%]). Fifteen patients presented with abdominal pain, and one patient had an interval increase in the size of the lesion from 9 to 12 cm. The size of hemangiomas varied from 6 to 23 cm. The median blood loss (enucleation: 350 vs. resection: 600 mL), operative time (enucleation: 5.8 vs. resection: 7.5 hours), and postoperative hospital stay (enucleation: 6.5 vs. resection: 11 days) were greater in the resection group (statistically insignificant). In the resection group, morbidity was significantly higher (62.6% vs. 12.5%, p = 0.05), including one mortality. All patients remained asymptomatic during the follow-up. Conclusions: Enucleation was simpler with less morbidity as compared to resection in our series. However, considering the small number of patients, further studies are needed with comparable groups to confirm the superiority of enucleation over resection.

• The Journal of the Acoustical Society of Korea
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• v.18 no.5
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• pp.35-43
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• 1999

In this paper, a new robust adaptive algorithm and a post-processing method are proposed to improve the performance of AEC without computational burden. Its step-size is normalized by the sum of the powers of the reference input signal and the desired signal. When the near-end speaker's speech and noise are applied into the microphone, the step-size becomes small and the misalignment of coefficients are reduced. To reduce the residual echoes, a new post-processing method, which is co-operated with the proposed noise-robust adaptive algorithm, is proposed in this paper. The method is based on the correlation of the desired signal and the estimation error signal. The residual echoes are attenuated as proportional to the correlation normalized with the power of desired signals. The normalized correlation plays a role as Wiener filter for residual echoes. In the double-talk situation, the estimation error signals, that are residual echoes, dominantly include the near-end speaker's speech and the normalized correlation closes to 1. Therefore, the near-end speaker's speech can be transmitted without being attenuated. When the desired signals consists of only the acoustic echoes, the residual echoes are mostly attenuated and canceled by the proposed post-processor. The computation of AEC using the proposed post-processor is comparable to NLMS algorithm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.2
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• pp.211-222
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• 2023

Multivariate quadratic equations (MQ)-based public-key cryptographic algorithms are one of promising post-quantumreplacements for currently used public-key cryptography. After selecting to NIST Post-Quantum Cryptography StandardizationRound 3 as one of digital signature finalists, Rainbow was cryptanalyzed by advanced algebraic attacks due to its multiple layered structure. The researches on MQ-based schemes are focusing on UOV with a single layer. In this paper, we propose a new MQ-signature scheme based on UOV using the combinations of the special structure of linear equations, spare polynomials and random polynomials to reduce the secret key size. Our scheme uses the block inversion method using half-sized blockmatrices to improve signing performance. We then provide security analysis, suggest secure parameters at three security levels and investigate their key sizes and signature sizes. Our scheme has the shortest signature length among post-quantumsignature schemes based on other hard problems and its secret key size is reduced by up to 97% compared to UOV.