• 한국산학기술학회논문지
• /
• 제19권9호
• /
• pp.384-390
• /
• 2018

기후변화와 도시화에 따른 오염으로 인하여 대기 및 토양이 오염되었고, 이들 오염물질이 점오염원과 비점오염원을 통하여 수질 내로 흘러 들어가면서 수질오염이 심각한 수준에 이르렀다. 이러한 수질 내 생물학적 오염원 제거를 위하여 간편하면서도 효율이 높은 수질 정화용 필터의 개발이 요구되는 실정이며, 이를 위하여 항균력을 가지고 있는 구리를 이용하여 연구를 진행하였다. 본 연구에서는 수질오염의 기준으로 사용되는 대장균 외 주요 병원성 균 4종 (Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa)을 사용하였으며, 스트립 형태의 구리선 0.5g, 1g, 2g을 이용하여 직경 2cm의 구 형태로 제작하였다. 항균력 확인을 위하여 각 병원성 균을 접종한 후 구리공을 장착한 다음, 99% 이상의 항균력을 가지는 조건을 조사하였다. 연구 결과 0.5g의 구리선으로 만든 구리 공을 최소 20분간 반응시켰을 때 5종의 병원성균에 대해서 99% 이상의 생장 억제능이 나타나는 것을 확인하였다. 본 연구 결과를 바탕으로 세포 실험 등의 추가 실험이 진행된다면 수질 정화용 필터로 사용되기에 충분할 것으로 판단되며, 이를 통해 공장 및 도시 폐수 뿐만 아니라 축산 및 양식 산업 분야에 광범위하게 적용될 수 있을 것으로 기대된다.

• ETRI Journal
• /
• 제25권2호
• /
• pp.65-72
• /
• 2003

To achieve cost and size reductions, we developed a low cost manufacturing technology for RF substrates and a high performance passive process technology for RF integrated passive devices (IPDs). The fabricated substrate is a conventional 6" Si wafer with a 25${\mu}m$ thick $SiO_2$ surface. This substrate showed a very good insertion loss of 0.03 dB/mm at 4 GHz, including the conductive metal loss, with a 50 ${\Omega}$ coplanar transmission line (W=50${\mu}m$, G=20${\mu}m$). Using benzo cyclo butene (BCB) interlayers and a 10 ${\mu}m$ Cu plating process, we made high Q rectangular and circular spiral inductors on Si that had record maximum quality factors of more than 100. The fabricated inductor library showed a maximum quality factor range of 30-120, depending on geometrical parameters and inductance values of 0.35-35 nH. We also fabricated small RF IPDs on a thick oxide Si substrate for use in handheld phone applications, such as antenna switch modules or front end modules, and high-speed wireless LAN applications. The chip sizes of the wafer-level-packaged RF IPDs and wire-bondable RF IPDs were 1.0-1.5$mm^2$ and 0.8-1.0$mm^2$, respectively. They showed very good insertion loss and RF performances. These substrate and passive process technologies will be widely utilized in hand-held RF modules and systems requiring low cost solutions and strict volumetric efficiencies.

• 한국산학기술학회논문지
• /
• 제3권1호
• /
• pp.32-37
• /
• 2002

Ca/sup 2+/ 이온은 식물조직의 경도 유지에 중요한 역할을 하는 것으로 알려져 있다. 따라서, Ca/sup 2+/의 첨가가 깍두기의 가식기간 연장에 미치는 영향, 적정 농도 및 효율적 첨가방법을 알아보고자 하였다. CaCl₂의 첨가에 의해 깍두기의 숙성기간 중 pH의 감소, 산도의 증가 및 기계적 경도의 감소 속도가 억제되어 가식기간이 연장되었다. 또한, Ca/sup 2+/ 첨가에 의해 관능적 특성 중 아삭함, 신맛 및 총체적인 기호도가 개선되었다. CaCl₂의 첨가방법과 농도는, 무를 절이는 염수에 0.1%의 CaCl₂를 첨가하고 절임과정이 끝나면 수세한 후 다시 양념과 함께 0.05%의 CaCl₂를 첨가하여 깍두기를 제조하는 것이 가장 효과적인 것으로 나타났다.

• Nuclear Engineering and Technology
• /
• 제34권1호
• /
• pp.30-41
• /
• 2002

The neutron beam is fully characterized for the prompt gamma activation analysis facility at Hanaro in the Korea Atomic Energy Research Institute(KAERI). The facility uses thermal neutrons which are diffracted vertically from a horizontal beam port by a set of pyrolytic graphite(PG) crystals positioned at the Bragg angle of 45" Neutron spectra, neutron flux and Cd-ratio are determined for the three extraction modes of diffracted beam by means of the theoretical and experimental efforts. To obtain theoretical result, the reflectivity of pyrolytic graphite is calculated in the diffraction model for mosaic crystal and the angular divergence after diffraction by mosaic crystal is estimated from Monte Carlo simulation. The time-of-flight spectrometer and gold activation wire are used for measuring the neutron spectra. Both the calculated and measured spectra have proven that the unique feature of polychromatic beam obtained by PG crystals are useful for PGAA. The thermal neutron flux of 7.9$\times$107 n/cm$^2$s and the Cd-ratio of 266 for gold have been achieved at the sample position while the reactor operates at 24 MW The uniformity of beam flux is 12% in the central 1$\times$1 cm$^2$ area. Finally, the beam is briefly characterized by the effective velocity and temperature which are determined by measuring the prompt Y-ray spectra for thin and thick boron samples.ples.

• 한국연소학회지
• /
• 제4권1호
• /
• pp.27-38
• /
• 1999

We constructed a wire-cylinder type pulsed corona discharge system for $NO_x$ removal, which was operated in room temperature. A emission spectrometer was built with a boxcar averager and monochrometer equipped with photo-multiplier tube detector. The sensitivity of the emission spectrometer was greatly improved by synchronizing the emission spectrometer with pulsed corona discharge system using a triggered spark-gap switch. $N_2$ spectrum($c^3{\Pi}_u{\rightarrow}X^1{\Sigma}_g{^+}$) was measured in the range of 300 - 450 nm and oxidizing OH radical emission($A^2{\Sigma}^+{\rightarrow}X^2{\Pi}$) was measured in case $N_2$ was supplied with water bubbling. As wet gas composition of inlet $N_2$ supplied in the discharge system increased, the intensity of OH emission was increased and saturated at wet gas composition 50%. We also investigated additive effect of $C_2H_4,\;H_2O,\;H_2O_2$ on the intensity of OR emission and $NO/NO_2/NO_x$ reduction and analysed the related reaction mechanism in corona discharge process. $H_2O_2$ additive increased the intensity of OH emission and $NO/NO_x$ reduction.

• Wind and Structures
• /
• 제18권1호
• /
• pp.83-101
• /
• 2014

Lamps installed on stay cables of cable-stayed bridges may alter the configuration of circular cross section of the cables and therefore result in aerodynamically unstable cable vibrations. The background of this study is a preliminary design of lamp installation on the cable-stayed He-dong Bridge in Guangzhou, China. Force measurements and dynamic response measurements wind tunnel tests were carried out to validate the possibility of cable galloping vibrations. It is observed that galloping will occur and the critical wind velocity is far less than the design wind velocity at Guangzhou City stipulated in Chinese Code. Numerical simulations utilizing software ANSYS CFX were subsequently performed and almost the same results as the wind tunnel tests were obtained. Moreover, the pressure and velocity contours around cable-lamp model obtained from numerical simulations indicated that the upstream steel wire in the preliminary design is the key factor for the onset of the galloping vibrations. A modification for the preliminary design of lamp installation, which suggests to remove the two parallel steel wires, is proposed, and it effectiveness is validated in further wind tunnel tests.

• 설비공학논문집
• /
• 제2권1호
• /
• pp.1-10
• /
• 1990

In the present study, the entrance length, velocity profiles and waveforms of developing transitional steady flows in a square duct are investigated analytically and experimentally. The systems of conservation equations for transitional steady duct flows are solved analytically by linearizing non-linear convective terms and adoption of modified eddy viscosity from empirical correlations. Analytical solutions of velocity profiles for developing transitional steady flow were obtained in the form of infinite series. The experimental study for transitional steady flow in a square duct with $40mm{\times}40mm{\times}4000mm$($width{\times}height{\times}length$) was carried out to measure velocity profiles and other parameters by using a hot-wire anemometer with data acquisition and processing system. The entrance length of developing transitional steady flows in a square duct was $L_e{\fallingdotseq}0.02{\cdot}Re,st{\cdot}D_h$, and the overshoot was occured at about 30 times of hydraulic diameter because of the effect of external velocity of boundary layer and instantaneous acceleration.

• 한국수산과학회지
• /
• 제14권4호
• /
• pp.212-216
• /
• 1981

호흡효소계의 영향을 미치는 vanillin, o-vanillin, guaiacol을 lactic acid 발효능이 있는 Lactobacillus bulgaricus에 처리한 후 합성배지에서 25시간동안 발효시킨 결과를 요약하면 다음과 같다. 1) 25시간 배양 후 도달한 균체농도는 vanllin 처리균의 경우 50ppm, 100ppn에서 각각 0.96UOD/ml, 0.29UOD/mg, 이고 o-vanillin의 경우 50ppn, 100ppm이 각각 0.40 UOD/ml, 0.45UOD/ml이며 guaiacol 경우 50ppm, 100ppn이 각각 0.49UOD/ml, 0.47 UOD/ml로 나타났다. 2) 배양후 포도당 잔량은 vanillin의 경수 50ppm, 100ppm이 각각 23.5g/1, 32.8g/1이고 o-vanillin의 500ppm, 100ppm이 각각 31.5g/1, 29.5g/l 이며 guaiacol 은 50 ppm. 100 ppm 이 각각 28.0g/1, 28.8g/l 였다. 3) specific growth rate는 vanillin의 경우 500ppm 및 100ppm이 각각 $0.44hr^{-1},\;0.15hr^{-1}$ 이고 o-vanillin의 경우 50ppm, 100ppm이 각각 $0.28hr^{-1},\;0.29hr^{-1}$ 이며 guaicol의 경우는 500ppm, 100ppm이 각각 $0.37hr^{-1},\;0.34hr^{-1}$이었다. 4) Specific production rate 는 vanillin의 경우 50ppm 및 100ppm 각각 $0.36hr^{-1},\;0.15hr^{-1}$이고 o-vanillln의 경우 50ppm, 100ppm이 각각 $0.16hr^{-1},\;0.22hr^{-1}$이며 guaiacol의 경우 50ppm, 100ppm이 각각 $0.28hr^{-1},\;0.26hr^{-1}$이었다.

• 전기학회논문지P
• /
• 제58권4호
• /
• pp.541-545
• /
• 2009

This study evaluated the contact resistance, insulation resistance, withstand voltage characteristics and insertion force, etc., of the wire connector used inside an integrated LITE WAY lighting fixture developed for efficient installation. Since the connector connecting the lighting fixture's internal wires is housed, it is easily connected and separated and has a structure enabling a close-fitting connection. The temperature and time applied to the high temperature characteristics test of the connector are $105^{\circ}C$ and 16 hours, respectively. The measured contact resistance of the high temperature tested connector was 3.258 mV/A, and its measured insulation resistance was greater than $10\;G{\Omega}$ All specimens demonstrated uniform insulation characteristics, which could be seen to be in good condition. From the withstand voltage test results found before and after performing the high temperature operation test on the connector for cable connection, it was confirmed that the withstand voltage characteristics between all terminals were good. The insertion force of the connector connecting the internal wiring averaged 9.67 kgf. It was observed that the insertion force between the plug housing and the female terminal, and that between the plug housing and the male terminal, were 0.680 kgf and 1.27 kgf on average, respectively.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 E
• /
• pp.1687-1689
• /
• 1998

In this work, the behaviours of conducting wire type particles within the coaxial electrode gap energized with high ac voltage have been systematically investigated using charge simulation method. For this, spheroidal charge is adopted as a image charge for the CSM analysis in order to calculate the acquired charge of the particles which are erected on the surface of the outer electrode. For this purpose, the effects of the lengths and diameters of Cu, Al particles in gas insulated system have been studied by a numerical computation and particle lifting voltage, lifting field, breakdown voltage, acquired charge and travelling distance have been considered. From this, we understand that the particle behaviours have different characteristics according to the particle lengths and diameters. And a possible countermeasure, based on the proposed simulation, has been provided with a view to estimating the flashover voltage of $SF_6$ gas under the 1 atm.