• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.45-48
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• 2008

This paper presents a brief overview of scalable video coding (SVC) with a focus on spatial scalability and its application to Advanced Terrestrial-DMB (AT-DMB). By adopting SVC with two spatial-layers and hierarchical modulation, AT-DMB provides standard definition (SD)-level video while maintaining compatability with the existing CIF-level video. In this paper, we suggest a layer-configuration and coding parameters of SVC which are well suit for an AT-DMB system. In order to reduce extremely large encoding time resulted by an exhaustive search of a macroblock coding mode in spatial scalability, we propose a fast mode decision method which excludes redundant modes in each layer. It utilizes the mode distribution of each layer and their correlations. Experimental results show that a simplified encoding model with the method reduces the computational complexity significantly with negligible coding loss.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.7
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• pp.76-84
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• 1994

The characteristics of 3 inch wafer scale GaAs epitaxial wafer grown by molecular beam epitaxy for LSI process application were studied. The thickness and doping uniformity are characterized and discussed. The growth temperature and growth rate were $600^{\circ}C$ by pyrometer, and 1 $\mu$m/h, respectively. It was found that thickness and doping uniformity were 3.97% and 4.74% respectively across the full 3 inch diameter GaAs epitaxial layer. Also, ungated MESFETs have been fabricated and saturation current measurement showed 4.5% uniformity on 3 inch, epitaxial layer, but uniformity of threshold voltage increase up to 9.2% after recess process for MESFET device.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.21-28
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• 2006

Structural health monitoring (SHM) is a new technology that will be increasingly applied at the industrial field as a potential approach to improve cost and convenience of structural inspection. Recently, the development of smart sensor is very active for real application. This study has focused on preparation and application study of SAL sensor. In order to detect elastic wave, smart piezoelectric sensor, SAL, is fabricated by using a piezoelectric element, shielding layer and protection layer. This protection layer plays an important role in a patched network of distributed piezoelectric sensor and shielding treatment. Four types of SAL sensor are designed/prepared/tested, and these details will be discussed in the paper. In this study, SAL sensor can be feasibly applied to perform structural health monitoring and to detect damage sources which result in elastic waves.

• Information Systems Review
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• v.3 no.2
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• pp.277-288
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• 2001

Of critical importance to the success of any e-commerce site are the two factors: rapid application development and quick response time. A three-tier architecture composed of presentation layer, business layer, and data access layer emerges to allow rapid changes in user interface, business logic, and database structures. Too often, such a logical three-tier architecture is considered as requiring a three-tier physical architecture: Web server, application server, and database server running on separate computers. Contrary to the common belief, a Web stress test reveals that the three-tier logical architecture implemented on a two-tier physical platform guarantees a quicker response time due to the reduction in cross-machine communications. This would lead business firms to economize their spending on e-commerce: increasing the number of physical servers to expedite transaction is not necessarily the best solution. Before selecting a particular hardware configuration, a Web stress test needs to be conducted to compare the relative merits of alternative physical architectures. Together with capacity planning, Web stress test emerges as a powerful tool to build robust, yet economical e-commerce sites.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.60-66
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• 2002

The remote measurement system(RMS) as a new experimental method is limited in its application to crack measurement at elevated temperatures because of the oxide layer on the specimen surface. Since TiAIN and Cr coating layers have a high resistance to oxidation and wear, this paper proposed a TiAIN and Cr coating technique for specimens to facilitate the measurement of crack growth behavior using RMS. To investigate the effects of the coating layer, tension and fatigue tests were carried out at room temperature and at $538^{\circ}C$. The test material was 1Cr-1Mo-0.25V steel which is widely used as a turbine rotor material. From the experimental results, it was found that the mechanical properties of the TiAIN and Cr coated specimens were similar to those of the substrate. Accordingly, the TiAIN and Cr coated layer had hardly any influence on the fatigue crack propagation.

• Journal of IKEEE
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• v.25 no.1
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• pp.37-41
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• 2021

In this paper, a low-profile and broadband bowtie antenna using multi-layer substrate for UWB sensor application is presented. A compact bowtie antenna is designed and implemented on two multi-layered substrate with total thickness of 4.5 mm. The antenna consists of bowtie radiator and planar-type balun. The designed radiator and balun are connected to each other so that it can be easily implemented in various structures. The implemented antenna provides 3 to 6 dBi of gain for whole frequency range from 6.8 to 10 GHz.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.2149-2170
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• 2017

Application-layer Distributed Denial-of-Service (DDoS) attack is one of the leading security problems in the Internet. In recent years, the attack strategies of application-layer DDoS have rapidly developed. This paper introduces a new attack strategy named Path Vulnerabilities-Based (PVB) attack. In this attack strategy, an attacker first analyzes the contents of web pages and subsequently measures the actual response time of each webpage to build a web-resource-weighted-directed graph. The attacker uses a Top M Longest Path algorithm to find M DDoS vulnerable paths that consume considerable resources when sequentially accessing the pages following any of those paths. A detection mechanism for such attack is also proposed and discussed. A finite-state machine is used to model the dynamical processes for the state of the user's session and monitor the PVB attacks. Numerical results based on real-traffic simulations reveal the efficiency of the attack strategy and the detection mechanism.

• The Journal of Korean Medicine
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• v.32 no.4
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• pp.68-74
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• 2011

Objective: The purpose of this study is to expatiate on high performance thin layer chromatography (HPTLC) as a simple, easy and scientific method for evaluation and standardization of herbal formulae. Methods: Through retrieving HPTLC application for herbal formulae in the literatures, the current situation of HPTLC application, and potential as well as limitation of HPTLC as a standardization method for multi-herbal drug was studied. Results: HPTLC is a speedy, inexpensive and well-operable tool for possessing multi-capability on component identification, separation, quantification and purification compared to other methods, such as high performance liquid chromatography (HPLC), gas chromatography (GC). Conclusions: HPTLC is considered as an available and convenient method for quality control and standardization of multi-herbal drugs. Thereby, this method could be recommended to widely applicate in the traditional Korean medicine.

• The KIPS Transactions:PartC
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• v.18C no.3
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• pp.127-134
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• 2011

Malicious botnet has been used for more malicious activities, such as DDoS attacks, sending spam messages, steal personal information, etc. To prevent this, many studies have been preceded. But malicious botnets have evolved and evaded detection systems. In particular, HTTP GET Request attack that exploits the vulnerability of the application layer is used. ALAB of ALADDIN proposed by ETRI is DDoS attack detection system that HTTP GET, Incomplete GET request flooding attack detection algorithm is applied. In this paper, we extend Incomplete GET detection algorithm of ALAB and derive the optimal configuration parameters to verify the validity of the algorithm ALAB by the study of the normal and attack packets.

• Corrosion Science and Technology
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• v.19 no.2
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• pp.51-56
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• 2020

The objective of this study was to improve properties of plasma sprayed HAp layer to titanium substrate by introducing an intermediate layer with two different methods. Before applying Zn doped HAp coating on titanium substrate, an intermediate layer was introduced by titanium plasma spray or titanium anodization. Heat treatments were conducted for some samples after titanium intermediate layer was formed. Zn doped HAp top layer was applied by plasma spraying. Three-point bending test and pull-off adhesion test were performed to determine the adhesion of Zn doped HAp coatings to substrates. Long-term credibility of Zn doped HAp plasma sprayed coatings on titanium was assessed by electrochemical impedance measurements in Hanks' solution. It was found that both titanium plasma sprayed and titanium anodized intermediate layer had excellent credibility. Strong adhesion to the titanium substrate was confirmed after 12 weeks of immersion for coating samples with titanium plasma sprayed intermediate layer. Samples with titanium anodized intermediate layer showed good bending strength. However, they showed relatively poor resistance against pulling off. The thickness of titanium anodized intermediate layer can be controlled much more precisely than that of plasma sprayed one, which is important for practical application.