• Bulletin of the Korean Chemical Society
• /
• v.35 no.10
• /
• pp.3052-3058
• /
• 2014

In this article, we have designed and synthesized a novel donor-${\pi}$-acceptor (D-${\pi}$-A) type porphyrin-based sensitizer (denoted UI-5), in which a carboxyl anchoring group and a 9,9-dimethyl fluorene were introduced at the meso-positions of porphyrin ring via phenylethynyl and ethynyl bridging units, respectively. Long alkoxy chains in ortho-positions of the phenyls were supposed to reduce the degree of dye aggregation, which tends to affect electron injection yield in a photovoltaic cell. The cyclic voltammetry was employed to determine the band gap of UI-5 to be 1.41 eV based on the HOMO and LUMO energy levels, which were estimated by the onset oxidation and reduction potentials. The incident monochromatic photon-to-current conversion efficiency of the UI-5 DSSC assembled with double-layer (20 nm-sized $TiO_2$/400 nm-sized $TiO_2$) film electrodes appeared lower upon overall ranges of the excitation wavelengths, but exhibited a higher value over the NIR ranges (${\lambda}$ = 650-700 nm) compared to the common reference sensitizer N719. The UI-5-sensitized cell yielded a relatively poor device performance with an overall conversion efficiency of 0.74% with a short circuit photocurrent density of $3.05mA/cm^2$, an open circuit voltage of 0.54 mV and a fill factor of 0.44 under the standard global air mass (AM 1.5) solar conditions. However, our report about the synthesis and the photovoltaic characteristics of a porphyrin-based sensitizer in a D-${\pi}$-A structure demonstrated a significant complex relationship between the sensitizer structure and the cell performance.

• Journal of Digital Contents Society
• /
• v.11 no.1
• /
• pp.25-38
• /
• 2010

There is no guideline or standard for the specification of the open-source-framework-based Spring AOP, and it causes confusion in development and maintenance. Moreover, the inconsistency between the existing MVC model, the AOP model that is used for Struts framework and the UML diagram makes the aspect reuse more difficult. In this study, a widened existing method was proposed so that Aspect, Pointcut and Advice could be expressed by either UML or XML to ensure that the Spring AOP can accept the combined use of the existing MVC model and the AOP model, which is used for Struts framework. Relationship was defined so that the mutual conversion could be possible with the proposed expression method, and the realization of simple development and maintenance was verified via the examples of mutual conversion. In addition, a packaging method to efficiently reuse aspect was proposed, and the possibility of reuse was verified.

• Korean Journal of Plant Resources
• /
• v.25 no.2
• /
• pp.240-245
• /
• 2012

In this study, we investigated the boosting effects on collagen biosynthesis of $Anthriscus$ $sylvestris$ ethanol extract (ASE) in human dermal fibroblasts. To obtain more effective fraction and subfraction for collagen biosynthesis, standard solvent partition and open column chromatography were performed. The EtOH extract, solvent fractions, and 8 EtOAc subfractions were tested for their collagen synthesis capacity by [$^3H$]Proline-incorporation and ELISA assay. ASE increased 25% of total collagen synthesis and 27% of procollagen biosynthesis. The total collagen biosynthesis was increased by EtOAc fraction and E6 subfraction to 28% and 50% respectively. Type I procollagens were also upregulated by EtOAc fraction and E6 subfraction to 30% and 47%, each. Taken together, our data suggest that potential anti-aging effect of ASE on skin is via increasing collagen biosynthesis and effective subtraction is E6 subfraction of EtOAc fraction.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.9
• /
• pp.91-101
• /
• 2012

Key exchange protocols are essential for building a secure communication channel over an insecure open network. In particular, password-based key exchange protocols are designed to work when user authentication is done via the use of passwords. But, passwords are easy for human beings to remember, but are low entropy and thus are subject to dictionary attacks. Recently, Zhao and Gu proposed a new server-aided protocol for password-based key exchange. Zhao and Gu's protocol was claimed to be provably secure in a formal adversarial model which captures the notion of leakage of ephemeral secret keys. In this paper, we mount a replay attack on Zhao and Gu's protocol and thereby show that unlike the claim of provable security, the protocol is not secure against leakage of ephemeral secret keys. Our result implies that Zhao and Gu's proof of security for the protocol is invalid.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.4
• /
• pp.615-626
• /
• 2016

In the paper, mild solvent soluble alkyl group modified epoxy resins were prepared via a three-step method; (1) the condensation reaction of dodecyl phenol (DP) and formaldehyde, (2) the crosslinking reaction of dodecyl phnol novolac compound (DPC) and bisphenol A diglycidyl ether, (3) the dodecyl phenol novolac epoxy resins containing fatty acid (DPFA) was prepared by introducing fatty acid to DPC. Equivalent ratios of DP and formaldehyde were 1.25~1.333/1.0. Equivalent ratio of DPC and bisphenol A diglycidyl ether (YD-128) was 1.0/2.0. Reactivity, viscosity, molecular weight, solvent solubility, and physical properties of DPFA were investigated. The result show that as the number of aromatic ring of DPFA increased, viscosity increased and solvent solubility improved. When we test the properties of coatings by blending the synthesized DPFA with a white pigment, DPFAC-5 using triphenylphosphine (TPP) as a ring-open catalyst showed optical performance for drying time, adhesion, hardness, impact resistance, acid resistance and storage stability.

• International journal of advanced smart convergence
• /
• v.5 no.4
• /
• pp.15-20
• /
• 2016

When a virtual sound source for 3D auditory system is reproduced by a linear loudspeaker array, listeners can perceive not only the direction of the source, but also its distance. Control over perceived distance has often been implemented via the adjustment of various acoustic parameters, such as loudness, spectrum change, and the direct-to-reverberant energy ratio; however, there is a neglected yet powerful cue to the distance of a nearby virtual sound source that can be manipulated for sources that are positioned away from the listener's median plane. This paper address the problem of generating binaural signals for moving sources in closed or in open environments. The proposed perceptual enhancement algorithm composed of three main parts is developed: propagation, reverberation and the effect of the head, torso and pinna. For propagation the effect of attenuation due to distance and molecular air-absorption is considered. Related to the interaction of sounds with the environment, especially in closed environments is reverberation. The effects of the head, torso and pinna on signals that arrive at the listener are also objectives of the consideration. The set of HRTF that have been used to simulate the virtual sound source environment for 3D auditory system. Special attention has been given to the modelling and interpolation of HRTFs for the generation of new transfer functions and definition of trajectories, definition of closed environment, etc. also be considered for their inclusion in the program to achieve realistic binaural renderings. The evaluation is implemented in MATLAB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.4
• /
• pp.424-434
• /
• 2015

Adaptive beamforming algorithms have been widely used to remove interference and jamming in the phased array radar system. Advances in the field programmable gate array(FPGA) technology now make possible the real time processing of adaptive beamforming (ABF) algorithm. In this paper, the FPGA based real-time implementation method of adaptive beamforming system(beamformer) in the pre-processor module for active electronically scanned array(AESA) radar is proposed. A compact FPGA-based adaptive beamformer is developed using commercial off the shelf(COTS) FPGA board with communication via OpenVPX(Virtual Path Cross-connect) backplane. This beamformer comprises a number of high speed complex processing including QR decomposition & back substitution for matrix inversion and complex vector/matrix calculations. The implemented result shows that the adaptive beamforming patterns through FPGA correspond with results of simulation through Matlab. And also confirms the possibility of application in AESA radar due to the real time processing of ABF algorithm through FPGA.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.05a
• /
• pp.456-458
• /
• 2017

In this capstone design, weather information using Web API (Application Programming Interface) was obtained from the web and based on the information, a realistic weather displayer was made that enables users to acquire weather information more conveniently and intuitively. To implement this, weather information data according to the region is retrieved through a open API providing weather information. Based on this data, the combination of LED, submersible pump, and humidifier module realized weather effect such as rain, fog, thunder, cloudy, and sunny. You can get weather information from various regions via WiFi and get real-time weather information by retrieving data after a single weather information expression routine. In addition to Wi-Fi, we have also tested the basic performance that enables users to express the desired weather effect by enabling weather expression through Bluetooth communication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.05a
• /
• pp.590-591
• /
• 2017

In the existing smart home, a separate platform was set up for each manufacturer to provide services through terminals. However, due to the development of Internet technology, various Internet devices and services have been launched, and there is a limit to the existing closed platforms for each manufacturer. Therefore, in this paper, we propose an object internet controller that integrates control of Internet devices in a smart home environment and provides various services through IFTTT. The proposed Internet controller is connected to the server via WiFi, and can control the Internet device and service of objects through the button input event. In addition, we expect to be able to provide a service environment that can create various smart home services by registering DIY products through open platform of oneM2M standard method.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.7A
• /
• pp.515-522
• /
• 2009

In this paper, a novel transmission scheme with spatial modulation is proposed for coded orthogonal frequency division multiplexing (OFDM). The multiple-input multiple-output (MIMO) technique, so-called spatial modulation (SM), divides input data into antenna index and data signals, transmitting data signals through the specific antenna chosen by the antenna index. In order to retrieve data stream at the receiver, SM needs to detect the antenna index which means that data signals are transmitted via a certain antenna. For this reason, it should be guaranteed that channel matrix is orthogonal. For the real environment, a MIMO channel has difficulty in maintaining orthogonality due to spatial correlation. Moreover, the receiver of the conventional SM is operated by hard decision, so that this scheme has a limit to be adopted for practical systems. Therefore, soft-output demappers for the conventional and proposed schemes are derived to detect antenna index and data stream by soft decision, and a novel transmission scheme combined with spatial modulation is proposed to improve the bit error rate (BER) performance of the conventional scheme.