• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.337-339
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• 2014

A facile one-pot synthesis of p-aminobenzoic acid from methyl 4-formylbenzoate which is a main by product in dimethyl terephthalate production process has been developed. This process involves the formation of amide intermediate obtained from the reaction of an aldehyde in methyl 4-formylbenzoate with chlorine in methylene chloride and the subsequent treatment of acid chloride with ammonia. The resulting amide was converted into amine using Hofmann degradation to afford a p-aminobenzoic acid. This facile one-pot process does not involve any expensive materials and should offer an attractive alternative to p-aminobenzoic acid production.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.07a
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• pp.263-265
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• 2020

본 논문에서는 다중 스케일로 구성된 뉴럴 네트워크를 이용하여 영상 내 모아레 무늬을 제거하는 기법을 제안한다. 제안하는 기법은 영상 피라미드를 생성하여 모아레 무늬를 구성하는 다양한 주파수 범위의 정보를 제거한다. 각 branch는 Multi-scale Feature Block (MFB)과 Tone-Mapping Block (TMB)으로 구성하여 효과적으로 모아레 현상을 제거하고 저하된 색상 저하를 복원한다. 컴퓨터 모의실험을 통해 제안하는 기법이 기존 기법에 비해서 높은 모아레 제거 성능을 보이는 것을 확인한다.

• The Korean Journal of Mycology
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• v.39 no.1
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• pp.31-38
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• 2011

In this study, 81 commercial strains of Pleurotus species cultivated in South Korea were analyzed with randomly amplified polymorphic DNA (RAPD) technique. Sequence characterized amplified region (SCAR) markers were developed by designing from one RAPD polymorhic band specific to Suhan strain. The SCAR primer pair 'S-OPA13-1' amplified a 590-bp fragment in the varieties originated from Suhan strain. The Blast search of S-OPA13-1 showed high homology to the POMFBO1 P. ostreatus cDNA clone MFB02-A05 and Laccaria bicolor S238N-H82. The results showed that this SCAR marker can clearly distinguish Suhan strains from Pleurotus spp.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.9-14
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• 2013

In this paper, we propose a low complexity bilateral search SIC for OFDM in fast time-varying channels. Due to the possibility of error propagation in SIC, symbol detection ordering within the block of symbols has a significant effect on the overall performance. In this paper, the first symbol to be detected is determined based on CSEP values, and then the next symbol to be detected is selected according to the updated CSEP while bilaterally searching from the boundary of the detected symbol group. Through computer simulations, we show that the proposed method has performance improvements with almost the same computation complexity over the conventional methods in the high SNR region. It has a performance approaching the MFB, known as the performance upper bound, within 2dB at the BER of $10^{-5}$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.4
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• pp.371-377
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• 2011

The aim of this study is to investigate the effects of aromatics and T90 temperature for high cetane number (CN) of diesel fuels on combustion and exhaust emissions in low-temperature diesel combustion in a 1.9 L common rail direct injection diesel engine at 1500 rpm and 2.6 bar BMEP. Four sets of fuels with CN 55, aromatic content of 20% or 45% (vol. %), and T90 temperature of $270^{\circ}C$ or $340^{\circ}C$ were tested. Given engine operating conditions, all the fuels showed the same tendency of decrease of PM with an increase of an ignition delay time. At the same ignition delay time, the fuels with high T90 produced higher PM. At the same MFB50% location the amount of NOx was similar for all the fuels. Furthermore, at the same ignition delay time the amounts of THC and CO were similar as well for all the fuels. The amount of THC and CO increased with an extension of the ignition delay time mainly because of the increase of fuel-air over-mixing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9A
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• pp.835-843
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• 2010

Energy spreading transform (EST) based equalization is a very effective technique to remove inter symbol interference (ISI) in frequency selective channel. EST based system uses cyclic prefix (CP) similar to orthogonal frequency division multiplexing (OFDM) system. Since CP is a redundancy, it degrades the data transmission rate. RISIC is an algorithm that removes an inter block interference (IBI) caused by insufficient CP length and reconstructs CP. In this paper, we propose a system that combines the existing EST system with quadrature phase shift keying (QPSK) modulation and RISIC algorithm to enhance the efficiency of the transmission. Also we extend the proposed system to 16 quadrature amplitude modulation (QAM) modulation. The proposed system is shown to performance close to matched filter bound (MFB) even with insufficient CP.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.1
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• pp.115-123
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• 2001

This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve gasoline optically accessible engine with swirl control valve(SCV). It adapted three different types of SCA(open ration 72.5%, 78%, 89%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt)were calculated to explain burn rate and flame speed. From acquired flame images, inspected the flame propagation direction, flame area, and flame centroid, Flame propagation direction was shown different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame image at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.172-179
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• 2001

Experimental studies have been carried out to find out the characteristics of the heat transfer, combustion emission and noise in the boilers without any extra firing zone for complete combustion of fuel. For the experiments a burner of premixed type and some heat exchangers were designed and manufactured. Also test facilities including a data acquisition system and various measuring devices were set up in order to measure automatically the various temperatures and flow rates of water and combustion gas. Various experiments were performed to find out the heat transfer characteristics as well as combustion emission and noise. In general, the burner which has uniform holes in the burner nozzle plate generates big combustion noise . whistling. The noise reduction method is discussed in this study. Many experimental data such as noise level, the amount of pollutant emission and heat transfer rate for different combination of heat exchangers are given as comparison bases for numerical studies.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.242-247
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• 2003

An experimental study presents characteristics of combustion in a combustion chamber by port deactivation valve for economy and emissions standards. In order to use combustion properties data it is necessary to build some data base, which use cylinder pressure sensor, etc. Port deactivation valve has been developed to satisfy requirement of achieving sufficient swirl generation to improve the combustion. A feasibility and necessity of combustion pressure based cylinder spark timing control has been examined. So, this was obtained the Coefficient of Variation(COV) and the mass-burned(MFB). The characteristics of pressure ratio fraction is similar to that of mass-burned fraction. Using the results of the test, the effects of the combustion chamber can be improved combustion stability by port deactivation.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.544-554
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• 1995

Pool boiling of dilute aqueous solutions of polyethylene oxide polymer has been experimentally investigated for the purpose of understanding the physical mechanisms of the suppression of vapor explosions in this polymer solution. Tn solid spheres of 22.2mm and 9.5mm-diameter ore heat-ed and quenched in the polymer solutions of various concentrations at 3$0^{\circ}C$. The results showed that minimum film boiling temperature($\Delta$ $T_{MFB}$) in this highly-subcooled liquid rapidly decreased from over $700^{\circ}C$ for pure water to about 15$0^{\circ}C$ as the polymer concentration was increased up to 300ppm for 22.2mm sphere, and it decreased to 35$0^{\circ}C$ for 9.5mm sphere. This large decrease of minimum film boiling temperature in this aqueous polymer solution may explain its ability to suppress spontaneous vapor explosions. Also, tests with applying a pressure wave showed that the vapor film behaved more stable against an external disturbance at higher polymer concentrations. These observations together with the experimental evidences of vapor explosion suppression in dilute polymer solutions suggest that the application of polymeric additives such as polyethylene oxide as low as 300ppm to reactor emergency coolant be considered to prevent or mitigate energetic fuel-coolant interactions during severe reactor accidents.s.