• 한국포장학회지
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• 제27권3호
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• pp.169-174
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• 2021

우리나라가 1인당 플라스틱 년간 소비량이 132 kg(2019)으로 세계1위로 나타났고, 지구온난화와 탄소중립을 위한 국제적 협약이 진해되고 있으며 소비자들도 바이오플라스틱에 대한 관심과 니즈가 증가하고 있어, 바이오플라스틱 소재에 복합 사용화 첨가제를 농도별로 첨가하여 필름을 생산 시 토출량, 용융지수, 인장강도 변화를 조사하였다. 석유계 수지인 LLDPE와 LDPE보다 PLA와 PBAT에서 용융지수가 현저히 높은 것으로 나타났으며 동일 수지나 동일 처리구에서는 heating temperature가 증가함에 따라 용융지수가 증가한 것으로 나타났다. 상용화제 4%를 첨가한 BDP-2 처리구에서 토출양도 비중도 우수한 것으로 조사되었으며, MD 및 TD 방향의 인장강도도 높게 나타나 BDP-2가 복합화 생분해 필름 제조용 제조 방법으로 가장 적합한 것으로 사료되었다.

• 전기의세계
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• 제30권5호
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• pp.306-312
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• 1981

The Townsend discharge domain is generally observed with stable positive characteristics in N$_{2}$ gas discharge at low pressures differently in the others, which transfer immediately to glow dischage after self-sustaining discharge starts. In this paper, the presence of the stable Townsend discharge, applied voltage-discharge current characteristics and the effect of disgased electrode surface on stable townsend discharge are studied experimentaly in N$_{2}$ gas mixed with 0.05% of No in volume. As the result of this experiment, the stable Townssend discharge is observed only in pure nitrogen with the valve of pd.geq.8[torr.cm] (p=gas pressure, d=gap spacing), but not in gas mixtures. This is considered that No gas in gas mixtures disexcites effectively the metestble state of nitrogen.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.121.1-121.1
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• 2014

Recently, much attention has been given to plasma production under liquid and its applications [1]. However, most of plasma production techniques reported so far utilize high voltage dc, ac, rf or microwave power [2], where damage to discharge electrodes and small discharge volume are remained issues. As an alternative of plasma production method under liquid, we have proposed pulsed microwave excited plasma using slot antenna, where damage to the slot electrode can be minimized and plasma volume can be increased. We have also reported improvement of treatment efficiency with use of reduced-pressure condition during the discharge [3]. To realize low pressure conditions in liquid, various alternative technique can be considered. One possible technique is simultaneous injection of microwave power and ultrasonic wave. Ultrasonic wave induces pressure fluctuation with the wave propagation and is so far used for cavitation production in the water. We propose utilization of reduced pressure induced by ultrasonic cavitation for improvement of the plasma production. Correlation between the plasma production and the ultrasonic power will be discussed.

• 대한기계학회논문집B
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• 제24권12호
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• pp.1652-1661
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• 2000

A visualization study using the schlieren method is adopted in an optically-accessible, cylindrical constant volume combustion chamber to identify the mechanism of ignition energy and ignition system interaction in spark ignited, lean gasoline-air mixture. In order to research the effects of ignition system on flame propagation, two kinds of ignition system are designed, and several kinds of spark plugs are tested and evaluated. To control the discharge energy, the dwell time is varied. The initial flame development is quantified in terms of 2-D images which provides information about the projected flame area and development velocity as a function of ignition system and discharge energy. The results show that high ignition energy and extended spark plug gap can shorten the combustion duration in lean mixtures. The material, diameter and configuration of electrodes the flame development by changing the transfer efficiency from electrical energy to chemical energy and discharge energy. However these factors do not affect of flame development as much a ignition energy or extended gap does.

• 한국농공학회논문집
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• 제61권4호
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• pp.55-61
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• 2019

Motor pumps cannot be used in those areas where electricity is not accessible such as remote rural areas in many African countries. Hydraulic ram pump is one of the solutions for supplying water for irrigation or domestic uses. The hydraulic ram pumps are working based on the water hammer effect for pumping without external power or electricity. This study was conducted to investigate the effect of air chamber volume and operation parameters on the performance of the hydraulic ram pump which was assembled with common plumbing parts. The experimental results showed the volume of the air chamber did not affect the performance such as discharge rate and head. When drive heights were 1.7 and 2.35 m, the maximum discharge heads were up to 7 m and 10 m, respectively. When the air chamber volume was 1 L, discharge rates were 0.23 and 2.12 L/min under the drive heights of 1.7 and 2.35 m, respectively. The average energy efficiency of the hydraulic ram pump assembled in this study was about 60% for all the experimental conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3418-3422
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• 2007

The neutron imaging technique was used to investigate the water discharge characteristics at PEMFC. Prior to investigation of water discharge characteristics, the linear attenuation coefficient for water at Neutron Radiography Facility (NRF) was calibrated. The feasibility test apparatus was consisted of pressurized air and water in order to simulate the actual operating PEMFC. The feasibility tests have been performed at 1-parallel serpentine type with 100 $cm^2$ active area and different air flow rate (1, 2, and 4 lpm). The total water volume variations at each condition were calculated from the neutron images. The water at channel is well discharged as soon as supplying the pressurized air into the PEMFC. However, because the water at MEA isn't removed the total water volume is constant after 150. Therefore more effective method is needed in order to discharge water at MEA, and the neutron imaging technique is helpful for it.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.275-278
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• 1997

We investigated effectness of sort and volume of conductive agent to charge/discharge capacity of LiMn$_2$O$_4$. LiMn$_2$O$_4$is prepared by reacting stoichiometric mixture of LiOH . $H_2O$ and MnO$_2$(mole ratio 1 : 2) and heating at 80$0^{\circ}C$ for 24h, 36h, 48h, 60h and 72h. All LiMn$_2$O$_4$cathode active materials show spinel structure. Cathode active materials calcined at 80$0^{\circ}C$ for 36h, charge/discharge characteristics and cycle stability have remarkable advantages. Used that super-s-black and 20wt% as conductive agent in LiMn$_2$O$_4$, it is excellent than property of cathode used Acetylene black or mixture of Super-s-black and acetylene black at charge/discharge capacity and cycle stability. Also, specific efficiency of cathode is excellent as over 98% and that of first cycle is excellent as 92%.

• 한국농공학회지
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• 제32권3호
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• pp.87-101
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• 1990

The purpose of this study is to estimate the flood discharge and runoff volume at a stream by using geomorphologic parameters obtained from the topographic maps following the law of stream classification and ordering by Horton and Strahier. The present model is modified from Cheng' s model which derives the geomorphologic instantaneous unit hydrograph. The present model uses the results of Laplace transformation and convolution intergral of probability density function of the travel time at each state. The stream flow velocity parameters are determined as a function of the rainfall intensity, and the effective rainfall is calculated by the SCS method. The total direct runoff volume until the time to peak is estimated by assuming a triangular hydrograph. The model is used to estimate the time to peak, the flood discharge, and the direct runoff at Andong, Imha. Geomchon, and Sunsan basin in the Nakdong River system. The results of the model application are as follows : 1.For each basin, as the rainfall intensity doubles form 1 mm/h to 2 mm/h with the same rainfall duration of 1 hour, the hydrographs show that the runoff volume doubles while the duration of the base flow and the time to peak are the same. This aggrees with the theory of the unit hydrograph. 2.Comparisions of the model predicted and observed values show that small relative errors of 0.44-7.4% of the flood discharge, and 1 hour difference in time to peak except the Geomchon basin which shows 10.32% and 2 hours respectively. 3.When the rainfall intensity is small, the error of flood discharge estimated by using this model is relatively large. The reason of this might be because of introducing the flood velocity concept in the stream flow velocity. 4.Total direct runoff volume until the time to peak estimated by using this model has small relative error comparing with the observed data. 5.The sensitivity analysis of velocity parameters to flood discharge shows that the flood discharge is sensitive to the velocity coefficient while it is insensitive to the ratio of arrival time of moving portion to that of storage portion of a stream and to the ratio of arrival time of stream to that of overland flow.

• 한국정밀공학회지
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• 제18권7호
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• pp.127-133
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• 2001

The effects of triangular and rectangular discharge current waveforms on anode erosion in wire electric discharge machining is investigated based on heat transfer analysis of half-space subject to time and space-dependent heat flux. The thermal load on the anode is simulated by a hear flux that is calculated from time-dependent discharge channel radius and energy. Evolution of the melting front during discharge, the molten volume at the experimental result for qualitative verification of the analysis. It is demonstrated that the triangular current waveform is more efficient in eroding the anode than the rectangular one.

• 조명전기설비학회논문지
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• 제30권1호
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• pp.66-71
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• 2016

In this study, electrical and spectroscopic characteristics were investigated in the pin to plate discharge of 0.9% weight per unit volume saline solution. The positive and positive- and negative-going dc pulse with 5% duty ratio were applied to tungsten pin electrode. The more amount of discharge current flew in negative discharge. The temperature, which is considered as a local value in the vicinity of vapor of discharge, was about 3,000K which is much higher than the value recommended to be controlled. It can be suggested that not only the temperature of liquid but also the local temperature of vapor is monitored to investigate damages on tissue or cells in biological application.