• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7990-8000
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• 2015

Plant factories are plant cultivation systems which produce farm products uniformly under the controlled environmental condition regardless of seasons and places. Thermal flow in the plant factory is an important parameter in cultivating plants. In this research, we study thermal flow characteristics for a hybrid plant factory with multi-layer cultivation shelves using computer simulation techniques. In order to obtain numerical solutions for thermal flow characteristics, a finite volume method was applied. We consider a low-Reynolds-number ${\kappa}-{\epsilon}$ turbulence model, incompressible viscous flows, and pressure boundary conditions for numerical simulation. Commercial software Solid Works Flow Simulation is then used to investigate characteristics of thermal flows in the plant factory applying several different inflow air velocities and arrangements of cultivation shelves. From numerical analysis results, we found that temperatures in cultivation shelves were uniformly distributed for Case 3 when the inflow air velocity was 1.6 m/s by using a blower in the plant factory. However in Case 1 lower temperature distributions were observed in test beds, TB2 and TB3, which indicated that additional temperature control efforts would be required. Average shelf temperature increased by $3^{\circ}C$ using artificial light source (DYLED47) with 50% blue and 50% red LED ratios. Korea Academia-Industrial cooperation Society.

• Membrane Journal
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• v.12 no.1
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• pp.8-20
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• 2002

In this study using $N_2$-back flushing, which wwas not the general back-flushing method of membranes, the discharged wastewater from a paper plant was filtrated by 4 kinds of tubular carbon ceramic ultrafiltration membranes. We could in vestigate effects of $N_2$-back flushing period, transmembrane pressure (TMP)and flow rate and find optimal operating conditions. The $N_2$-back flushing time (BT) was fixed at 40 sec, filtration times (FT) were changed in 4~32 min, TNP in $1.0~3.0kg_f/cm^2$ the flow celocities in 0.53~1.09cm/s. The optimal conditions were discussed in the viewpoints of dimensionless permeate flux ($J/J_0$), toal permeate volume ($V_T$) and resistance of membrane fouling ($R_f$). Optimal back-flushing period was BT/FT=0.167 (FT=8 min ), in which more $V_T$ was obtained than that in BT/FT=0.083 (FT=4 min) which was the most friquent back-flushing condition. Then rising TMP should increase the driving force, and more $V_T$ could be accumulated. And rising flow rate should decrease membrane fouling increase permeate flux, and more $V_T$could be produced. Average rejection rates of pollutants were higher than 95% for turbidity and 45~83% for $COD_{Cr}$, but rejection rates of total dissolved solid (TDS) were lower than 10%.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.456-456
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• 2010

CMOS 소자가 서브마이크론($0.1\;{\mu}m$) 이하로 스케일다운 되면서 단채널 효과(short channel effect), 게이트 산화막(gate oxide)의 누설전류(leakage current)의 증가와 높은 직렬저항(series resistance) 등의 문제가 발생한다. CMOS 소자의 구동전류(drive current)를 높이고, 단채널 효과를 줄이기 위한 가장 효율적인 방법은 소스 및 드레인의 얕은 접합(shallow junction) 형성과 직렬 저항을 줄이는 것이다. 플라즈마 도핑 방법은 플라즈마 밀도 컨트롤, 주입 바이어스 전압 조절 등을 통해 저 에너지 이온주입법보다 기판 손상 및 표면 결함의 생성을 억제하면서 고농도로 얕은 접합을 형성할 수 있다. 그리고 얕은 접합을 형성하기 위해 주입된 불순물의 활성화와 확산을 위해 후속 열처리 공정은 높은 온도에서 짧은 시간 열처리하여 불순물 물질의 활성화를 높여주면서 열처리로 인한 접합 깊이를 얕게 해야 한다. 그러나 접합의 깊이가 줄어듦에 따라서 소스 및 드레인의 표면 저항(sheet resistance)과 접촉저항(contact resistance)이 급격하게 증가하는 문제점이 있다. 이러한 표면저항과 접촉저항을 줄이기 위한 방안으로 실리사이드 박막(silicide thin film)을 형성하는 방법이 사용되고 있다. 본 논문에서는 (100) p-type 웨이퍼 He(90 %) 가스로 희석된 $PH_3$(10 %) 가스를 사용하여 플라즈마 도핑을 실시하였다. 10 mTorr의 압력에서 200 W RF 파워를 인가하여 플라즈마를 생성하였고 도핑은 바이어스 전압 -1 kV에서 60 초 동안 실시하였다. 얕은 접합을 형성하기 위한 불순물의 활성화는 ArF(193 nm) excimer laser를 통해 $460\;mJ/cm^2$의 에니지로 열처리를 실시하였다. 그리고 낮은 접촉비저항과 표면저항을 얻기 위해 metal sputter를 통해 TiN/Ti를 $800/400\;{\AA}$ 증착하고 metal RTP를 사용하여 실리사이드 형성 온도를 $650{\sim}800^{\circ}C$까지 60 초 동안 열처리를 실시하여 $TiSi_2$ 박막을 형성하였다. 그리고 $TiSi_2$의 두께를 측정하기 위해 TEM(Transmission Electron Microscopy)을 측정하였다. 화학적 결합상태를 분석하기 위해 XPS(X-ray photoelectronic)와 XRD(X-ray diffraction)를 측정하였다. 접촉비저항, 접촉저항과 표면저항을 분석하기 위해 TLM(Transfer Length Method) 패턴을 제작하여 I-V 특성을 측정하였다. TEM 측정결과 $TiSi_2$의 두께는 약 $580{\AA}$ 정도이고 morphology는 안정적이고 실리사이드 집괴 현상은 발견되지 않았다. XPS와 XRD 분석결과 실리사이드 형성 온도가 $700^{\circ}C$에서 C54 형태의 $TiSi_2$ 박막이 형성되었고 가장 낮은 접촉비저항과 접촉저항 값을 가진다.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.6
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• pp.47-54
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• 2020

The acupressure is a treatment that applies pressure to certain parts of the body and has been mainly used for pain relief in the field of oriental medicine. However, the treatment effect is often different depending on the practitioner's ability, experience, and physical strength, so standardized acupressure is needed. In this regard, the equipment is being released, but this is mainly a rolling massage method, which reduces energy concentration and poses a risk of injury. Therefore, in this study, a device that provides vertical acupressure based on variable bogie (wheel truck) was implemented. As a result of experimenting with load and body pressure distribution and desirability to validate the device's bearing pressure, the acupressure rod held up to 150kg, the body pressure ratio was measured lower than the body pressure ratio of the comparison item in section 0%

• The Journal of the Convergence on Culture Technology
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• v.9 no.1
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• pp.619-625
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• 2023

In this paper, the remote care of medical beds with multiple body pressure sensors is described. Falling is one of the factors that seriously threaten the safety of patients and harm their health. In this study, a new bed was developed to overcome this. The bed system consists of a keyboard that can operate, a keyboard controller that manages the movement of the keyboard, a sensor that measures body pressure, a sensor controller that transmits and receives sensor values, a main controller that checks it and operates automatically or manually according to the algorithm, and a server that oversees all these information. The bed system checks the patient's location through a sensor and wirelessly alerts the server through the main controller when the patient determines that there is a risk of falling, so that the nurse or nurse can recognize the patient's dangerous condition. The server may receive state data transmitted from the wired/wireless terminal to monitor whether the bed system is operating normally. The controller of the keyboard operates a keyboard-type mechanism and automatically controls the prevention of bedsores connected by body pressure sensors to physically separate the area to which the patient's pressure is applied to prevent bedsores. The main controller checks the presence of the patient's bed and transmits it to the server. In conclusion, the proposed system can smart monitor the user's state and perform remote care.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.2
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• pp.239-251
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• 2024

In this study, a hydrogen fuel cell process based on methanol was developed to reduce greenhouse gas emissions. In Case1, the methanol fuel engine system was designed to investigate the emission of exhaust gas when methanol was supplied as fuel instead of gasoline to the engine. In Case2, a hydrogen fuel cell system was designed by adding a methanol reforming system to Case1. This hybrid system produced gray hydrogen and combined the output of the engine and fuel cell to drive the ship. However, gray hydrogen emits carbon in the process of producing hydrogen. To address this problem, a carbon capture and utilization (CCU) system was added to Case3. The CO2 of the flue gas discharged from Case2 was synthesized with gray hydrogen to produce blue methanol. The results of the case studies revealed that the optimal operating conditions were 220 ℃, 500 kPa, SCR = 1.0, and flow ratio = 0.7. The system of Case3 reduced carbon emissions by 42% compared with that Case1. Thus, the hybrid system of Case3 could considerably reduce the ship's CO2 emissions.

• Journal of Chest Surgery
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• v.36 no.3
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• pp.123-130
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• 2003

Background: In order to develop the acute heart failure model for the animal experiment of the pneumatic ventricular assist device, we decided to use young pig whose coronary artery distribution is almost the same as humans and also very cheap in price. The purpose of this study is to develop stable, reproducible acute ischemic heart failure model in swine using coronary artery ligation method. Material and Method: Five young pigs whose weights are the same as adult humans are under experiment. Each pig was under endotracheal intubation and connected to a mechanical ventilator. Through left lateral thoracotomy, we exposed the heart and induced ischemic heart failure by coronary artery ligation. The ligation began at the distal part of the left anterior descending coronary artery. After 5 minutes of initial ligation we reperfused the artery and then re-ligated. Before and after each ligation-reperfusion procedure we assessed the left ventricular end-diastolic pressure, arterial pressure, and cardiac index. We also measured left ventricular end-diastolic dimension, end-systolic dimension, fractional shortening, ejection fraction using intraoperative epicardial echocardiography. After appropriate heart failure was established with sequential (from distal part of LAD to proximal location) ligation-reperfusion-ligation procedure, we inserted the ventricular assist device and operated. Result: We established stable acute ischemic heart failure in 3 of 5 young pigs with this sequential ligation-reperfusion-ligation procedure, and could maintained 50% less ejection fraction before the procedure according to intraoperative epicardial echocardiography. We also observed no ventricular arrhythmia usually associated with simple coronary artery ligation in large animals and no cardiac arrest associated with ventricular arrhythmia or myocardial stunning. In pathologic specimen, we observed scattered ischemic myocardium in all around the ischemic field induced by coronary artery ligation. Conclusion: Under the concept of ischemic preconditioning, we developed safe and reproducible acute ischemic heart failure model in swine using sequential coronary artery ligation-reperfusion-ligation method.

• Journal of Chest Surgery
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• v.37 no.6
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• pp.482-491
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• 2004

Background: The xenogenic or allogenic valves after in Vitro repopulation with autologous cells or in vivo repo-pulation after acellularization treatment to remove the antigenicity could used as an alternative to synthetic polymer scaffold. In the present study, we evaluated the process of repopulation by recipient cell to the acellu-larized xenograft treated with NaCl-SDS solution and grafted in the right ventricular outflow tract. Material and Method: Porcine pulmonary valved conduit were treated with. NaCl-SDS solution to make the grafts acellularized and implanted in the right ventricular outflow tract of the goats under cardiopulmonary bypass. After evaluating the functions of pulmonary valves by echocardiography, goats were sacrificed at 1 week, 1 month, 3 months, 6 months, and 12 months after implantation, respectively. After retrieving the implanted valved conduits, histopathologic examination with Hematoxylin-Eosin, Masson' trichrome staining and immunohistochemical staining was performed. Result: Among the six goats, which had been implanted with acellularized pulmonary valved conduits, five survived the expected time period. Echocardiographic examinations for pulmonary valves revealed good function except mild regurgitation and stenosis. Microscopic analysis of the leaflets showed progressive cellular in-growth, composed of fibroblasts, myofibroblasts, and endothelial cells, into the acellularized leaflets over time. Severe inflammatory respon-se was detected in early phase, though it gradually decreased afterwards. The extracellular matrices were regenerated by repopulated cells on the recellularized portion of the acellularized leaflet. Conclusion: The acellularized xenogenic pulmonary valved conuits were repopulated with fibroblasts, myofibroblasts, and endothelial cells of the recipient and extracellullar matrices were regenerated by repopulted cells 12 months after the implantation. The functional integrity of pulmonary valves was well preserved. This study showed that the acellularized porcine xenogenic valved conduits could be used as an ideal valve prosthesis with long term durability.

• Journal of the Korean Vacuum Society
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• v.18 no.1
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• pp.66-72
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• 2009

The detection methods are required to monitor and diagnose the abnormality on the insulation condition inside a gas-insulated switchgear (GIS). Due to a good sensitivity to the products decomposed by partial discharges (PDs) in $SF_6$ gas, the development of a SWNT gas sensor is actively in progress. However, a few numerical studies on the diffusion mechanism of the $SF_6$ decomposition products by PD have been reported. In this study, we modeled $SF_6$ decomposition process in a chamber by calculating temperature, pressure and concentration of the decomposition products by using a commercial CFD program in conjunction with experimental data. It was assumed that the mass production rate and the generation temperature of the decomposition products were $5.04{\times}10^{-10}$ [g/s] and over 773 K respectively. To calculate the concentration equation, the Schmidt number was specified to get the diffusion coefficient functioned by viscosity and density of $SF_6$ gas instead rather than setting it directly. The results showed that the drive potential is governed mainly by the gradient of the decomposition concentration. A lower concentration of the decomposition products was observed as the sensors were placed more away from the discharge region. Also, the concentration increased by increasing the discharge time. By installing multiple sensors the location of PD is expected to be identified by monitoring the response time of the sensors, and the information should be very useful for the diagnosis and maintenance of GIS.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.3
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• pp.33-38
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• 2021

Recently, rollable and foldable displays are attracting great attention in the flexible display market due to their excellent form factor. To predict and prevent the mechanical failure of the display panels, it is essential to accurately understand the mechanical properties of brittle SiN_x thin films, which have been used as an insulating film in flexible displays. In this study, tensile properties of the ~130 nm- and ~320 nm-thick SiN_x thin films were successfully measured by coating a ~190 nm-thick organic nano-support-layer (PMMA, PS, P3HT) on the fragile SiN_x thin films and stretching the films as a bilayer state. Young's modulus values of the ~130 nm and ~320 nm SiN_x thin films fabricated through the controlled chamber pressure and deposition power (A: 1250 mTorr, 450 W/B: 1000 mTorr, 600 W/C: 750 mTorr, 700 W) were calculated as A: 76.6±3.5, B: 85.8±4.6, C: 117.4±6.5 GPa and A: 100.1±12.9, B: 117.9±9.7, C: 159.6 GPa, respectively. As a result, Young's modulus of ~320 nm SiN_x thin films fabricated through the same deposition condition increased compared to the ~130 nm SiN_x thin films. The tensile testing method using the organic nano-support-layer was effective in the precise measurement of the mechanical properties of the brittle thin films. The method developed in this study can contribute to the robust design of the rollable and foldable displays by enabling quantitative measurement of mechanical properties of fragile thin films for flexible displays.