• Journal of Biosystems Engineering
• /
• 제36권1호
• /
• pp.15-22
• /
• 2011

An experimental variable rate nursery sprayer was developed to adjust application rates for canopy volume in real time. The sprayer consisted of two vertical booms integrated with ultrasonic sensors, and variable rate nozzles coupled with pulse width modulation (PMW) based solenoid valves. A custom-designed microcontroller instructed the sensors to detect canopy size and occurrence and then controlled nozzles to achieve variable application rates. A spray delivery system, which consisted of diaphragm pump, pressure regulator and 4-cycle gasoline engine, offered the spray discharge function. Spray delay time, time adjustment in spray trigger for the leading distance of the sensor, was measured with a high-speed camera, and it was from 50 to 140 ms earlier than the desired time (398 ms) at 3.2 km/h under indoor conditions. Consequently, the sprayer triggered 4.5 to 12.5 cm prior to detected targets. Duty cycles of the sprayer were from 20 to 34 ms for senor-to-canopy (STC) distance from 0.30 to 0.76 m. Outdoor test confirmed that the nozzles were triggered from 290 to 380 ms after detecting tree canopy at 3.2 km/h. The spray rate of the new sprayer was 58.4 to 85.2% of the constant application rate (935 L/ha). Spray coverage was collected at four areas of evergreen canopy by water sensitive papers (WSP), and ranged from 1.9 to 41.1% and 1.8 to 34.7% for variable and constant rate applications, respectively. One WSP area had significant (P < 0.05) difference in mean spray coverage between two application conditions.

• Tribology and Lubricants
• /
• 제33권2호
• /
• pp.37-44
• /
• 2017

A DE-side LBP tilting pad journal bearing of a 1-stage overhung heat-pump compressor in a propylene process exhibited abnormal high-temperature behavior. Its temperature had been relatively high at $78^{\circ}C$ from the beginning of operation. In 2014, after three years of operation, it increased suddenly and reached $103^{\circ}C$. Installing a varnish removal equipment and others managed to stabilize the temperature at $95^{\circ}C$. We undertook a troubleshooting approach for reviewing the comprehensive status and integrity of the temperature design of the bearing. We performed lubrication and heat-balance analysis, based on the design engineering data and documents supplied by the OEM. For the base design data of DE-side TPJB, evaluating the effects of key design variables on bearing metal temperature showed that firstly, increasing the bearing clearance and supply oil flow-rate, and next, changing the oil type, and finally, increasing the machined pad clearance and offset, are more effective in reducing the bearing metal temperature. Furthermore, a clarification meeting with the OEM revealed that an incorrect decision had been made to decrease the bearing clearance to eliminate the SSV harshness issue, while not maintaining a sufficient oil flow-rate. We conducted a detailed retrofit design analysis, wherein we increased the oil flow-rate and bearing clearance by decreasing the preload. We predicted that the bearing temperature would decrease to $63^{\circ}C$ from $75.7^{\circ}C$ even at the rerate condition. Finally, after installing and operating a retrofit replacement bearing in 2015, the bearing temperature stabilized at a low temperature of $65^{\circ}C$. Currently (January. 2017), two year later, the bearing metal temperature remains at $65^{\circ}C$. Therefore, we can conclude that the abnormal high-temperature behavior of the bearing has been resolved completely.

• 대한기계학회논문집A
• /
• 제40권6호
• /
• pp.581-585
• /
• 2016

최근 고령화 사회에 진입과 소득수준이 향상됨에 따라 의료 수요가 빠르게 증가되고 있다. 이중 신약 개발은 의료분야의 핵심 분야 중 하나로 전 세계적으로 많은 투자가 연구가 이루어지고 있다. 신약 개발의 중요한 과제 중 하나는 다양한 후보를 빠르고 정확하게 발굴하는 자동화 시스템을 개발하는 것이다. 고속으로 후보물질을 발굴하는 기술 중 대표적 기술이 세포 기반 고집적 스크리닝 시스템(High Contents Screening, 이하 HCS) 기술이다. 이 HCS 시스템에서 다양한 물질을 한꺼번에 스크리닝하기 위해서는 다기능 고정밀 디스팬서 제작이 필수적이다. 본 연구에서는 기존의 HCS 디스팬서 시스템이 가지고 있는 단점을 보완하기 위해 에어건과 압력 구동식 펌프를 이용한 새로운 컨셉의 비접촉식 디스팬서를 개발하고 그 가능성을 확인한다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2009년도 추계학술대회 논문집
• /
• pp.571-571
• /
• 2009

지열은 날씨와 기온 등에 영향을 받지 않고 연중 가동할 수 있어 기저부하를 담담할 수 있는 유일한 신재생에너지 자원이므로 이에 대한 기술개발이 시급하다. 우리나라는 비화산지대이며 지중 온도가 가장 높은 지역의 5km에서 약 $170^{\circ}C$ 내외이므로 외국에 비해 지온경사도가 크지 않은 편이다. 그리고 3km 이상에서는 지하대수층이 거의 존재하지 않기 때문에 지열발전을 위해서는 EGS 기법을 도입할 수 밖에 없는 실정이다. 그리고 지열수를 확보할 수 있는 온도범위가 약 $100{\sim}150^{\circ}C$ 정도이므로 이에 적합한 지열발전 플랜트를 선정할 필요가 있다. 일반적으로 지열발전에 적용되는 플랜트는 건증기 지열발전, 플래쉬증기 지열발전, 바이너리 사이클 지열발전으로 분류할 수가 있으나 국내 여건에 맞는 방식으로서 바이너리 사이클 발전으로서 ORC 플랜트 또는 Kalina 사이클 플랜트가 적합하므로 이에 대한 기술 개발이 적극적으로 이루어져야 한다. 따라서 국내 지열발전의 기술개발에 있어서 핵심요소는 심부천공 및 EGS를 위한 인공파쇄기술과 지상 플랜트로서 저온지열 발전 플랜트의 기술확보가 필요한 실정이다. 이와 같은 기술개발이 완성되면 발전 뿐만아니라 집단지역난방, 온실 및 양어장 등에도 열공급이 가능한 열병합발전이 가능하게 될 것이다. 또한, EGS 기술로서 상업적 성공을 이룬 것은 세계적으로 2~3개 사례에 불과한 신기술로서, EGS 기술의 국내 조기 실현으로 기술 선점 및 해외 수출을 모색할 필요가 있다. 그리고 심부 지열자원은 국내 어디에나 부존하는 ubiquitous 자원이며 이산화탄소 배출이 전무한 청정 국산 에너지 자원이나, 이의 개발에는 높은 초기 투자비와 risk를 요하므로 민간 업체의 투자가 제약을 받는다. 따라서 정부의 적극적인 지원하에 산.학.연 중심으로 시범보급이 우선 이루어진 후 민간의 자발적 투자를 통한 지열 개발을 유도할 필요가 있다.

• Molecules and Cells
• /
• 제42권12호
• /
• pp.850-857
• /
• 2019

The Gram-negative opportunistic pathogen, Pseudomonas aeruginosa, has multiple multidrug efflux pumps. MexT, a LysR-type transcriptional regulator, functions as a transcriptional activator of the MexEF-OprN efflux system. MexT consists of an N-terminal DNA-binding domain and a C-terminal regulatory domain (RD). Little is known regarding MexT ligands and its mechanism of activation. We elucidated the crystal structure of the MexT RD at 2.0 Å resolution. The structure comprised two protomer chains in a dimeric arrangement. MexT possessed an arginine-rich region and a hydrophobic patch lined by a variable loop, both of which are putative ligand-binding sites. The three-dimensional structure of MexT provided clues to the interacting ligand structure. A DNase I footprinting assay of full-length MexT identified two MexT-binding sequence in the mexEF-oprN promoter. Our findings enhance the understanding of the regulation of MexT-dependent activation of efflux pumps.

• 대한수의학회지
• /
• 제33권2호
• /
• pp.199-209
• /
• 1993

The effects of ${\alpha}_1$-adrenergic stimulation on membrane potential, intracellular sodium activity $(a_N{^i{_a}})$, and contractility were investigated in the isolated papillary muscle of euthyroid, hyperthyroid, and hypothyroid guinea pigs. Cardiac alterations in the thyroid state have been shown to induce marked changes in action potential characteristics, the most pronounced shortening of action potential duration by hyperthyroidism and an increase in duration by hypothyroidism. $10^{-5}M$ Phenylephrine produced a decrease in $(a_N{^i{_a}})$ in euthyroid and hypothyroid preparations, but an increase in $(a_N{^i{_a}})$ in hyperthyroid ones. The major findings were that phenylephrine produced a stronger positive inotropic effect(PIE) without initial negative inotropic effect(NIE) in hyperthyroid preparations, while phenylephrine produced markedly NIE in hypothyroid ones. The alterations in membrane potential, $(a_N{^i{_a}})$, and contractility were abolished by $3{\times}10^{-5}M$ prazosin in hypothyroidism. In hypothyroid ventricular muscle, the decrease in $(a_N{^i{_a}})$ caused by phenylephrine were not abolished or reduced by $10^{-5}M$ strophanthidin, $10^{-5}M$ TTX, $3{\times}10^{-4}M$ lidocaine, or $100^{-5}M$ verapamil. These results indicate that the ${\alpha}_1$-adrenoceptor-mediated decrease in $(a_N{^i{_a}})$ is not associated with a stimulation of the $Na^+$-$K^+$ pump, inhibition of the $Na^+$ or $Ca^+$ channel in hypothyroid ventricular muscle. $10^{-5}M$ Phenylephrine decreased $(a_N{^i{_a}})$ but increased $(a_N{^i{_a}})$ in the presence of a PKC activator phorbol dibutyrate$(PDB_u)$. In conclusion, it is suggested that the following sequence of events in response to phenyleplhane occur in guinea pig ventricular muscle. First, changes in thyroid state may contribute to the ventacular electrophysiological propeties or ion transport system. Second, the adrenoceptor-mediated initial transient NIE may be associated with the decrease in $(a_N{^i{_a}})$ by PKC activation.

• 상하수도학회지
• /
• 제25권4호
• /
• pp.581-589
• /
• 2011

Generally, treated water or raw water is transported into storage reservoirs which are receiving facilities of local governments from multi-regional water supply systems. A water supply control and operation center is operated not only to manage the water facilities more economically and efficiently but also to mitigate the shortage of water resources due to the increase in water consumption. To achieve the goal, important information such as the flow-rate in the systems, water levels of storage reservoirs or tanks, and pump-operation schedule should be considered based on the resonable water demand forecasting. However, it is difficult to acquire the pattern of water demand used in local government, since the operating information is not shared between multi-regional and local water systems. The pattern of water demand is irregular and unpredictable. Also, additional changes such as an abrupt accident and frequent changes of electric power rates could occur. Consequently, it is not easy to forecast accurate water demands. Therefore, it is necessary to introduce a short-term water demands forecasting and to develop an application of the forecasting models. In this study, the forecasting simulator for water demand is developed based on mathematical and neural network methods as linear and non-linear models to implement the optimal water demands forecasting. It is shown that MLP(Multi-Layered Perceptron) and ANFIS(Adaptive Neuro-Fuzzy Inference System) can be applied to obtain better forecasting results in multi-regional water supply systems with a large scale and local water supply systems with small or medium scale than conventional methods, respectively.

• The Korean Journal of Pain
• /
• 제12권1호
• /
• pp.21-26
• /
• 1999

Background: Preoperative blocking of surgical nociceptive inputs may prevent sensitization of central nervous system (CNS) and reduce postoperative pain. The stress responses to surgical trauma consist of increase in catabolic hormones and decrease in anabolic hormones. We studied whether preoperative low dose epidural bupivacaine and morphine could affect postoperative pain, changes plasma cortisol, and serum glucose. Methods: Thirty patients undergoing total abdominal hysterectomy were randomly assigned to one of three groups. General anesthesia was induced in all patients and after that, epidural blocks were done except the control group (n=10) patients. Preoperative block group (n=10) received 0.5% bupivacaine 50 mg and morphine 2 mg epidurally as a bolus before operation and followed by 0.1% bupivacaine $5\;mghr^{-1}$ and morphine $0.2\;mghr^{-1}$ for 10 hours. Postoperative block group (n=10) received the same doses of bupivacaine and morphine under the same method postoperatively. Postoperative pain relief was provided with i.v. fentanyl through Patient-Controlled-Analgesia Pump. Postoperative pain by visual analogue scores (VAS), analgesic requirement (first requirement time, total amounts used), side effects, plasma cortisol level and serum glucose level were compared. Results: Until postoperative 6 hrs, VAS of control group was higher than those of the epidural groups. No difference was observed in VAS between the two epidural groups. First analgesics requirement time and total amounts of used analgesics were not different between the two epidural groups, but first analgesic requirement time of preoperative block group was significantly prolonged compared with control group. Plasma cortisol and serum glucose levels were not different among groups. Conclusions: Low dose preoperative epidural bupivacaine and morphine could not reduce postoperative pain, plasma cortisol level and serum glucose level compared with postoperative block group.

• 한국화재소방학회논문지
• /
• 제32권5호
• /
• pp.57-66
• /
• 2018

29명이 사망하고 40명이 부상을 입은 제천 스포츠센터 화재 사례에 대해 다수 사상자가 발생한 원인을 초기대응과 관리적인 측면을 중심으로 분석하였다. 초기대응 측면은 119신고 지연, 2층 세신사 비상구로 피난유도를 하지 않음, 1층과 3층 비상계단쪽 방화문 개방 상태 유지, 3층 주계단실 쪽 방화문 닫지 않음, 비상방송을 하지 않음으로 분석하였다. 관리적인 측면은 1층의 스프링클러설비 알람밸브 폐쇄, 소방펌프 제어반에서 기동 정지 위치에 놓음, 주차장 반자 안 누수 및 누전 방치, 2층 여탕의 휴게실 피난구유도등이 가려져 있고 비상구에 물건이 적치됨, 2층 자동문의 조작버튼 불량상태로 방치, 형식적인 소방안전관리, 소방시설 부실한 자체점검, 방화셔터와 배연창 미작동으로 분석하였다.

• Nuclear Engineering and Technology
• /
• 제46권5호
• /
• pp.633-640
• /
• 2014

In this research, the surface roughness affecting the pressure drop in a pipe used as the steam generator of a PWR was studied. Based on the CFD (Computational Fluid Dynamics) technique using a commercial code named ANSYS-FLUENT, a straight pipe was modeled to obtain the Darcy frictional coefficient, changed with a range of various surface roughness ratios as well as Reynolds numbers. The result is validated by the comparison with a Moody chart to set the appropriate size of grids at the wall for the correct consideration of surface roughness. The pressure drop in a full-scale U-shaped pipe is measured with the same code, correlated with the surface roughness ratio. In the next stage, we studied a reduced scale model of a U-shaped heat pipe with experiment and analysis of the investigation into fluid-structure interaction (FSI). The material of the pipe was cut from the real heat pipe of a material named Inconel 690 alloy, now used in steam generators. The accelerations at the fixed stations on the outer surface of the pipe model are measured in the series of time history, and Fourier transformed to the frequency domain. The natural frequency of three leading modes were traced from the FFT data, and compared with the result of a numerical analysis for unsteady, incompressible flow. The corresponding mode shapes and maximum displacement are obtained numerically from the FSI simulation with the coupling of the commercial codes, ANSYS-FLUENT and TRANSIENT_STRUCTURAL. The primary frequencies for the model system consist of three parts: structural vibration, BPF(blade pass frequency) of pump, and fluid-structure interaction.