• Polymer(Korea)
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• v.35 no.6
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• pp.593-598
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• 2011

The IPA-co-HDO-co-(TPA/MA) copolymers for all-vanadium redox flow battery were synthesized by melt condensation polymerization using isophthalic acid(IPA), 1,6-hexandiol (HDO), terephthalic acid(TPA) and maleic anhydride(MA). The amination of chloromethylated IPA-co- HDO-co-(TPA/MA)(CIHTM) copolymer was carried out using trimethylamine, and the anion exchange membrane was also prepared by UV crosslinking reaction. The structure and thermal stability of IHTM copolymers were confirmed by FTIR, $^1H$ NMR, and TGA analysis. The anion membrane properties such as water uptake, ion exchange capacity, electric resistance and electrical conductivity, were measured by gravimetry, titration and LCR meter. The efficiency of the all-vanadium redox flow battery was analyzed. The ion exchange capacity, electric resistance and electrical conductivity were 1.10 meq/g, $1.98{\Omega}{\cdot}cm^2$, and 0.009 S/cm, respectively. The efficiency of charge-discharge, voltage, and energy for the allvanadium redox flow battery were 96.5, 74.6, 70.0%, respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.495-495
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• 2017

도시화는 불투수면의 증가를 야기 시켜 물순환 왜곡, 다양한 오염 물질의 유입으로 인한 비점오염물질 유출, 인공 배출열의 증가로 인한 도시열섬효과 등 다양한 문제를 유발한다. 이러한 수리수문학적 및 환경생태학적 문제를 저감하기 위하여 도시지역과 같은 개발 사업에서는 수환경을 가능한 자연 상태로 복원하는 저영향개발(Low Impact Development, LID)기법이 중요한 대안으로 제시되고 있다. LID기법 중 하나인 옥상녹화는 에너지 이용을 최소한으로 한 자연 녹음의 효과적인 이용을 도모하여 환경공생도시 조성과 식물을 매개로한 자연 순환 과정을 도시구조에 도입하여 순환 시스템 재생이 가능 하도록한다. 노지녹화는 두꺼운 자연 토양을 이용하는 반면 옥상녹화는 적재하중의 제약(옥상의 적재하중 조건은 $150{\sim}180kgf/m^2$이다. 비중이 1.6~1.8인 토양을 20cm 객토한 경우, 약 $320kgf/m^2 $이상의 적재하중이 되기에 식재기반의 경량화는 중요한 사안이다.)으로 인해 용적밀도가 작은 인공경량토양 또는 개량토양을 이용하며, 토양 두께도 얇게 설정된다. 또한 토양의 두께는 식물의 크기와 종류 및 토양의 조성에 따라 다르기에 적재하중 조건을 고려한 적절한 토양과 식재 식물의 크기와 종류 결정은 중요하다. 이에 본 연구에서는 옥상녹화식생에 대한 평가와 이에 대한 시험 프로세스가 가능한 실험 장치를 개발하였다. 옥상녹화 효율성 검증실험장비는 1m*1m*0.6m 아크릴 재질의 녹화셀로 경사조절이 가능하도록 설계하여 경사변화에 따른 유출, 침투, 증발산량의 탄성도 모의 평가를 할 수 있다. 또한 4점식 형태의 로드셀을 이용하여 녹화셀에서 발생하는 증발산량을 측정하고 관측된 증발산량은 RS-232c 이상의 통신프로토콜을 사용하여 주기적인 관측치의 송수신이 가능하며 주기적 자료송수신 외에도 옥상 녹화셀의 측면에 하중 표시기를 설치하여 관측이 가능하다. 또한 저면에 바퀴설치를 통하여 이동 실험이 용이하며 현재 부산대학교 양산캠퍼스 한국 GI&LID 실증단지 연구센터 내 옥상녹화 실험장에 옥상녹화 효율성 검증 실험 장비를 설치하여 자연 혹은 인공강우를 통한 유출, 침투, 증발산량의 시험계측을 실시중이다. 이러한 옥상녹화 효율성 검증실험장비는 최대 하중 2,000kg, 측정해상도 0.02kg 이상을 허용하는 로드셀과 녹화셀을 이용하여 하중을 고려한 식생의 종류에 따른 평가가 가능하므로 최적 식재기반 단면구조 개발에 이용될 수 있을 것이다. 또한 토양 함수량 변화 측정으로 옥상녹화에 이용되는 다양한 종류의 식물의 염분에 대한 저항성과 식물의 성장능력을 평가하여 녹화공간에 따른 옥상녹화에 사용할 식생을 결정할 수 있다.

• Elastomers and Composites
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• v.38 no.3
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• pp.235-242
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• 2003

A vulcanization reaction characteristics of an isoprene rubber (IR)-modified natural rubber/carbon black (NR/CB) composite was studied using in-situ electrical property measuring technique. Since the electrical conductivity of the sample composite would be changed continuously during the vulcanization reaction by rearranging of the carbon black particles within the sample, volume resistivity (${\rho}$) might be obtained as a function or reaction time. A stabilization time ($t_i$), maximum reaction speed time ($t_p$), and volume resistivity at that time(${\rho}_p$) were defined from the data for the Arrhenius analysis. Volume resistivity ${\rho}$ showed a comparatively high value of ${\sim}10^8$ order before the reaction started, and dramatically decreased to be stabilized within $1{\sim}2$ minutes as soon as the reaction started. As the more time elapsed, thereafter, ${\rho}$ decreased monotonously to a certain constant value through a peak, ${\rho}_p$ at time $t_p$, which was considered as the maximum reaction rate. As a result, while $t_i$ values were comparatively constant as $1{\sim}2$ minutes, $t_p$ values showed to become shorter and shorter as the reaction temperature.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.1-8
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• 2020

Communication between system modules is applied using the Modbus protocol in industrial sites including smart factories, industrial drones, building energy management systems, PLCs, ships, trains, and airplanes. The existing Modbus was used for serial communication, but the recent Modbus protocol is used for TCP/IP communication.The Modbus protocol supports RTU, TCP and ASCII, and implements and uses protocols in embedded systems. However, the transmission I/O devices for RTU, TCP, and ASCII-based protocols may differ. For example, RTU and ASCII communications transmit on a serial-based communication protocol, but in some cases, Ethernet TCP/IP transmission is required. In particular, since the C language (object-oriented) is used in embedded systems, the complexity of source code related to I/O registers increases. In this study, we designed software that can logically separate I/O functions from embedded devices, and designed the execution logic of each instance requiring I/O processing through a delegate class instance with Modbus RTU, TCP, and ASCII protocol generation. We designed and experimented with software that can separate communication I/O processing and logical execution logic for each instance.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.743-748
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• 2019

This study focuses on the simulation of wet flue gas desulfurization process for improving the production of gypsum by the utilization of low-grade limestone. At present, high-grade limestone with a $CaCO_3$ content of 94% is used for producing merchantable gypsum. In modeling process, a lot of reactions are considered to develop model. First, the limestone dissolution is simulated by RSTOIC model. Second, SOx absorption and crystallization is used by RCSTR model. Finally the gypsum is separated by using SEPERATORS model. Modeling steps make it easy to reflect further side reactions and physical disturbances. In optimization condition, constraints are set to 93% purity of gypsum, 94% desulfurization efficiency, and total use of limestone at 3710 kg/hr. Under these constraints, the mass flow of low-grade limestone was maximized. As a result, the maximum blending quantity of low-grade limestone for 2,100 kg of high-grade limestone that satisfies constraints is about 1,610 kg.

• Journal of the Korean Geosynthetics Society
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• v.18 no.1
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• pp.25-37
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• 2019

This study confirms reinforcing effect of geosynthetics in the use of soil at higher water contents as a compaction material on compaction tests, field compaction tests, and numerical analysis. To verify a confined effect, a large mold(area ratio of rammer / mold = 0.19) larger than D compaction mold(area ratio of rammer / mold = 0.33) was performed for compaction. It showed that in the D compaction test, dry density were 0.5~0.6% increases and in the compaction test using the large mold, it were 2.4~3.7% increases at high water contents. It shows that when the area of compacted area is large enough, a confined effect could be arising from the reinforcement of geosynthetics even at high water contents. As a result of analyzing of compaction effects according to 'depth(z/B) from compacted surface' in the field, when not reinforced, the compaction state deteriorated due to the over-compaction and the compaction did not work well. However, when reinforcement of geosynthetics, restraint effect by geosynthetics occurs, it is confirmed that the compaction energy is effectively transferred to the compaction layer and the dry density is increased. Also, through the conceptual model of the behavior of geosynthetic and soil layer, the mechanism in the ground due to reinforcement of geosynthetics is presented and it is verified through finite element analysis.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.358-367
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• 2019

Adsorption equilibrium and intraparticle diffusion characteristics of benzene, toluene, and xylene vapors on activated carbon and zeolite 13X were investigated. Static adsorption experiments were carried out under the pressure range of 0.01~0.07 bar while changing the adsorption temperature to 293.15 K, 303.15 K, and 313.15 K, respectively. Adsorption equilibrium was analyzed by Langmuir, Freundlich and Toth models. The adsorption energy was 5.26~31.0 kJ/mol representing physical adsorption characteristics. The maximum adsorption capacity on activated carbon was the largest for benzene, and the smallest for xylene. Toluene was in between. In the case of zeolite 13X, the maximum adsorption capacity was the largest for xylene, and the smallest for benzene as opposed to activated carbon. The effective diffusion coefficients of gas adsorbate were measured to be about $10^{-5}{\sim}10^{-4}cm^2/s$, and increased with temperature. As the pressure increased, the effective diffusion coefficients were decreased. The dependence of effective diffusion coefficients on temperature and pressure was greater in zeolite 13X particles than in activated carbon. Therefore, it is necessary to express the diffusion coefficients as a function of pressure in order to predict the precise dynamic behavior of the adsorption process using zeolite 13X where the pressure fluctuation occurs abruptly.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.46-54
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• 2021

In this paper, active noise control was performed to reduce radiated noise in the low frequency band of dishwashers. First, through an analysis of the noise environment of the dishwasher, it was confirmed that the pump noise contributed the most to the radiated noise in the low frequency band, From the result of the noise environment analysis, the reference signal was selected to be the vibration signal of the pump body. The reference signal was obtained by using the accelerometer on the pump body, which can prevent acoustic feedback. The error signal sensor was selected as a microphone located at 1 m in front of the dishwasher and 0.5 m in height. And to design the controller, the error signal and the reference signal were measured at the operational rpms of the dishwasher at 2,500 rpm, 2,600 rpm and 2,800 rpm, and the secondary path transfer function was measured. The designed controller was mounted on Digital Signal Processor (DSP) equipment, and the control performance was verified experimentally. As a result of the measurement at the 3 operational rpms, the 7th multiple component of pump operating frequency decreased by 1.93 dB, 4.43 dB, 5.15 dB per rpm, and the 12th multiple component decreased by 6.67 dB, 2.34 dB, 4.28 dB per rpm. And overall Sound Pressure Level (SPL) decreased by 0.84 dB, 2.58 dB, 1.48 dB by rpm.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.603-609
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• 2022

The dose distribution in the human body was evaluated and analyzed through dosimetry data using water phantom, ionization chamber and simulated by Monte Carlo simulation for ^99mTc and ¹⁸F sources, which are frequently used in the nuclear medicine in this study. As a result of this study, it was found that the dose decreased exponentially as the distance from the radioisotope increased, and it particularly showed a tendency to decrease sharply when the radioisotope was separated by 5 cm. It means that a large amount of dose is delivered to an organ located within 4 cm of source's movement path when a source uptake in the human body. Numerically, it was formed in the rage of 0.16 to 2.16 pC/min for ^99mTc and 0.49 to 9.29 pC/min for ¹⁸F. In addition, the energy transfer coefficient calculated using the result was found to be similar to the measured value and the simulation value in the range of 0.240 to 0.260. Especially, when the measured data and the simulation value were compared, there was a difference is within 2%, so the reliability of the data was secured. In this study, the distribution of radiation generated from a source was calculated to quantitatively evaluate the internal dose by radioisotopes. It presented reliable results through comparative analysis of the measurement value and simulation value. Above all, it has a great significance to the point that it was presented by directly measuring the distribution of radiation in the human body.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.11-19
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• 2010

ZigBee is a standard for wireless personal area networks(WPANs) based on the IEEE 802.15.4 standard. It has been developed for low cost and low power consumption. There are two alternative routing schemes that have been proposed for the ZigBee standard: Ad-hoc On-Demand Distance Vector(AODV) and tree routing. The tree routing forwards packets from sensors to a sink node based on the parent-child relationships established by the IEEE 802.15.4 MAC topology formation procedure. In order to join the network, a sensor node chooses an existing node with the strongest RSSI(Received signal strength indicator) signal as a parent node. Therefore, some nodes carry a large amount of traffic load and exhaust their energy rapidly. To overcome this problem, we introduce a new metric based on link quality and traffic load for load balancing. Instead of the strength of RSSI, the proposed scheme uses the new metric to choose a parent node during the topology formation procedure. Extensive simulation results using TOSSIM(TinyOS mote SIMulator) show that the CFR scheme outperforms well in comparison to the conventional tree routing scheme.