• Nuclear Engineering and Technology
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• v.39 no.1
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• pp.1-8
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• 2007

Hydrogen and electricity are expected to dominate the world energy system in the long term. The world currently consumes about 50 million metric tons of hydrogen per year, with the bulk of it being consumed by the chemical and refining industries. The demand for hydrogen is expected to increase, especially if the U.S. and other countries shift their energy usage towards a hydrogen economy, with hydrogen consumed as an energy commodity by the transportation, residential and commercial sectors. However, there is strong motivation to not use fossil fuels in the future as a feedstock for hydrogen production, because the greenhouse gas carbon dioxide is a byproduct and fossil fuel prices are expected to increase significantly. An advanced reactor technology receiving considerable international interest for both electricity and hydrogen production, is the modular helium reactor (MHR), which is a passively safe concept that has evolved from earlier high-temperature gas-cooled reactor (HTGR) designs. For hydrogen production, this concept is referred to as the H2-MHR. Two different hydrogen production technologies are being investigated for the H2-MHR; an advanced sulfur-iodine (SI) thermochemical water splitting process and high-temperature electrolysis (HTE). This paper describes pre-conceptual design descriptions and economic evaluations of full-scale, nth-of-a-kind SI-Based and HTE-Based H2-MHR plants. Hydrogen production costs for both types of plants are estimated to be approximately $2 per kilogram.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.1
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• pp.79-85
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• 2017

In this paper, several optimizations are proposed to enhance the quality of lane detection algorithms in automotive applications. Considering the diagonal directions of lanes, the proposed limited Hough transform newly introduces image-splitting and angle-limiting schemes that relax the number of possible angles at the line voting process. In addition, unnecessary edges along the horizontal and vertical directions are pre-defined and removed during the edge detection procedures, increasing the detecting accuracy remarkably. Simulation results shows that the proposed lane recognition algorithm achieves an accuracy of more than 90% and a computing speed of 92 frame/sec, which are superior to the results from the previous algorithms.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.121-125
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• 2004

The preprocessor - solver - postprocessor software for 2D/Axisymmetric CSCM Upwind Flux Difference Splitting Navier-Stokes code has been developed for undergraduate educational purpose. This computational fluid dynamics (CFD) software allows students to setup, solve, visualize and control dynamically server for their own fluid problems via Internet. The preprocessor Is capable of generating geometry and grid, initial solution data and required solver control parameters. The postprocessor shows vector plot and contour plot with different options while residual plot shows root-mean-square (RMS) error history graphically and retrieves the data from solver interactively. Special feature of the preprocessor is grid generation part which is based on MFC/Visual C++ application and FORTRAN single block grid generator process. Many users can access solver via Internet from client computers and solve desired problems using locally installed pre- and postprocessor and remote powerful solver part.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.469-474
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• 2009

Purpose: A lower facial contouring surgery has become a commonly performed procedure in Asia. Currently, mandibular angle sagittal ostectomy and botulinum toxin type A treatment are main procedures for aesthetic correction of a broad lower face. There are a few date to show the differences in the mandibular contouring changes between mandibular angle splitting ostectomy and botulinum toxin type A treatment. Facial golden mask is easy to apply, inexpensive, and relatively objective for evaluation of facial contour analysis. This study was designed specifically to compare the changes in lower face width after two different forms of lower facial contouring procedure using facial golden mask. Methods: Seventeen patients, aged 18 to 55 years (mean, 28.6 years), 15 women and 2 men, consented to the study and receive a contouring procedure of lower face. The patients were classified in to 2 groups. In group A, the sample consisted of 10 patients with a prominent squared mandibular angle and mandibular angle splitting ostectomy was performed. In group B, the sample consisted of 7 patients with masseteric hypertrophy and botulinum toxin type A treatment was performed. Photographs of the face were taken to record the facial change at preoperative and postoperative. The postoperative photographs were taken to considered maximal effect at 2 years after surgery in group A and 4.8 months after treatment in group B. The authors applied the facial golden mask to preoperative and postoperative photographs and horizontal ratio, which compares facial width with golden mask width, were calculated. We made an analysis of the result of horizontal ratio using SPSS. Results: Overall average horizontal ratio of pre- and postoperative photos of group A were 1.24 and 1.11, whereas overall average horizontal ratio of pre- and postoperative photos of group B were 1.19 and 1.12. The horizontal ratio decreased 10.24% in group A and 5.93% in group B. There was a statistically significant change in before and after treatment, but there was no significant change in comparing the group A and group B. Conclusions: The result from this study suggest that mandibular angle sagittal ostectomy and botulinum toxin type A treatment showed relatively satisfactory clinical effects on lower facial contouring treatment. There was no statistical significant difference within two lower facial contouring treatment. Facial golden mask is easy to apply, inexpensive, and relatively objective, so we think that facial golden mask is a good method for evaluation of lower facial contouring treatment.

• Journal of the Korean Professional Engineers Association
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• v.18 no.3
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• pp.1-20
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• 1985

The traffic congestion of Seoul city has been one of the most serious problems to be settled since the advent of 1970s. As a means to mitigate traffic mess, the authority concerned launched the construction of subway line 3 and 4 in 1980. The two Subway lines slated for completion by 1985 cross each other and run north-south direction, passing through the metropolitan area of Seoul city fraught with high-rise edifices and large-scale shopping centers, and, in order to reduce blasting vibration, NATM was executed for a distance of 10 Km, instead of ASSM previously employed when subway line 1 and 2 were constructed. Tunnel blastings were implemented, preceded by classifying the rocks at construction area into five categories, namely, hard rock, semi-hard rock, weak rock weathered rock and silt and by calculating their respective specific charges through standard test blastings, by employing the pre-splitting and smooth blasting with drilling patterns of burn cut type, so as not to cause damages to surface structures. Most of explosives used were the slurry of low specific gravity and low velocity, and the firings executed by the use of milli-second detonators. Empiric formula were also formulated to check blasting vibrations, based on the vibration allowable values of West Germany standard, for the application to vulnerable construction zones. Should the two lines be placed for public service in 1985, about 40% of the total traffic population of Seoul city amounting to 15 million as of 1984 is estimated to be carried by subway with no difficulties.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.4
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• pp.100-106
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• 2007

In this paper, first we went through the deliming and degreasing as pre-treatment of limed pelt scrap which is derived from liming process during leather manufacturing processing. After that, we produced fine collagen using non-chrome tanning and heat treatment and using acryl monomer graft polymerization such as GMA and MMA. From the comparisonof final products made by various methods, they showed good features in pyrolysis temperature, heat-resisting, variation of moisture content and particle distribution.

• Advances in concrete construction
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• v.9 no.2
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• pp.173-181
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• 2020

Fracture properties of concrete depend on the mix proportions of the ingredients, specimen shape and size, type of testing method used for the evaluation of fracture properties. Aggregates play a key role for changes in the fracture behaviour of concrete as they constitute about 60-75 % of the total volume of the concrete. The present study deals with the effect of size and quantity of coarse aggregate on the fracture behaviour of steel fibre reinforced self compacting concrete (SFRSCC). Lower coarse aggregate and higher fine aggregate content in SCC results in the stronger interfacial transition zone and a weaker stiffness of concrete compared to vibrated concrete. As the fracture properties depend on the aggregates quantity and size particularly in SCC, three nominal sizes (20 mm, 16 mm and 12.5 mm) and three coarse to fine aggregate proportions (50-50, 45-55, 40-60) were chosen as parameters. Wedge Split Test (WST), a stable test method was adopted to arrive the requisite properties. Specimens without and with guide notch were investigated. The results are indicative of increase in fracture energy with increase in coarse aggregate size and quantity. The splitting force was maximum for specimens with 12.5 mm size which is associated with a brittle failure in the pre-ultimate stage followed by a ductile failure due to the presence of steel fibres in the post-peak stage.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.2
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• pp.943-952
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• 2021

The purpose of this study is to evaluate the effect of COVID-19 on corporate governance attributes and firm performance association. This research used a sample of 188 non-financial firms from the Malaysian market for the years 2019-2020. We found that the COVID-19 has affected all firm characteristics including firm performance, governance structure, dividend, liquidity, and leverage level, yet, the difference between prior and post COVID-19 pandemic is not significant. Also, the investigation revealed that board size exerts a significant positive impact on firm performance. After splitting the sample based on year, however, we found that board size does not matter in the uncertain time of the current crisis, while board diversity appeared to be significantly enhancing firm performance in the crisis time compared to the prior year where it has an inverse association with firm performance in both indicators. Board meetings and audit committee meetings seemed to have a significant negative influence on firm performance pre and post-COVID-19. This study contributes to the limited literature by providing the first empirical evidence on the impact of Coronavirus on the firm performance and corporate governance association.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.199-210
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• 2002

In this paper, we carried out the study on speech recognition using the KM-Net topology design algorithm based on decision tree state-clustering to improve the performance of acoustic models in speech recognition. The Korean has many allophonic and grammatical rules compared to other languages, so we investigate the allophonic variations, which defined the Korean phonetics, and construct the phoneme question set for phonetic decision tree. The basic idea of the HM-Net topology design algorithm is that it has the basic structure of SSS (Successive State Splitting) algorithm and split again the states of the context-dependent acoustic models pre-constructed. That is, it have generated. the phonetic decision tree using the phoneme question sets each the state of models, and have iteratively trained the state sequence of the context-dependent acoustic models using the PDT-SSS (Phonetic Decision Tree-based SSS) algorithm. To verify the effectiveness of the above algorithm we carried out the speech recognition experiments for 452 words of center for Korean language Engineering (KLE452) and 200 sentences of air flight reservation task (YNU200). Experimental results show that the recognition accuracy has progressively improved according to the number of states variations after perform the splitting of states in the phoneme, word and continuous speech recognition experiments respectively. Through the experiments, we have got the average 71.5%, 99.2% of the phoneme, word recognition accuracy when the state number is 2,000, respectively and the average 91.6% of the continuous speech recognition accuracy when the state number is 800. Also we haute carried out the word recognition experiments using the HTK (HMM Too1kit) which is performed the state tying, compared to share the parameters of the HM-Net topology design algorithm. In word recognition experiments, the HM-Net topology design algorithm has an average of 4.0% higher recognition accuracy than the context-dependent acoustic models generated by the HTK implying the effectiveness of it.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.2
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• pp.335-344
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• 2016

It is known that power analysis is one of the most powerful attack in side channel analysis. Among power analysis single trace attack is widely studied recently since it uses one power consumption trace to recover secret key of public cryptosystem. Recently Sim et al. proposed new exponentiation algorithm for RSA cryptosystem with higher attack complexity to prevent single trace attack. In this paper we analyze the vulnerability of exponentiation algorithm described by Sim et al. Sim et al. applied message blinding and random exponentiation splitting method on $2^t-ary$ for higher attack complexity. However we can reveal private key using information exposed during pre-computation generation. Also we describe modified algorithm that provides higher attack complexity on collision attack. Proposed algorithm minimized the reuse of value that are used during exponentiation to provide security under single collision attack.