• 대한기계학회논문집B
• /
• 제31권10호
• /
• pp.876-883
• /
• 2007

Numerical simulations are conducted for the design of a micro thermal mass air flow sensor (MAFS), which consists of a microfabricated heater and thermopiles on the silicon-nitride ($Si_3N_4$) thin membrane structure. It is important to find the proper locations of these thermal elements in the design of MAFS with improved sensitivity. Three heating modes of the micro-heater are considered: constant temperature, constant power and heating pulses. The analyses are focused on the membrane temperature profile near the sensing section. Considered are the practical flow velocities, ranging from 3 m/s to 35 m/s, and the corresponding Reynolds numbers from 1000 to 10000. The results show that one of optimum sensing locations is about $100{\mu}m$ away from the microheater. It is concluded that the heating mode and configurations of thermal elements are the main factors for the MAFS with higher sensitivity.

• 한국항해학회지
• /
• 제20권3호
• /
• pp.1-11
• /
• 1996

The accuracy for determining fishing ground and for setting fishing gear location, and the repeatability of ship position vary depending on fishing methods. Especially, Loran-C has been served to give fisherman highly accurate ship's position, and a number of fishing vessel are equipped with it's receivers. In this paper, in order to evaluate the accuracy of Loran-C fix of Korean chain in Korean southeast coast, the authors examined and analyzed the data of the receiver of Loran-C(LC 90, Furuno) and GPS(AccNav $Sport^{TM}$, Eagle) measured automatically and continuously for 2 seconds at interval of 5minutes during 2hours from $11^{th}$ to $21^{st}$, July, 1996 at six observed points, that is, Pusan, Wolnae, Pangojin, Chongja, Kampo and Kuryongpo in Korean southeast coast. As the result obtained, Loran-C signals showed little fluctuation with good reprodutibility. Good stability of Loran-C signals was indicated by the small value of the standard deviation 0.064~0.094$\mu\textrm{s}$. Although determination of the observed position could not be completely accurate, the extent of the error was estimated smaller than 0.35 nautical mile.

• The Korean Journal of Pain
• /
• 제9권1호
• /
• pp.260-263
• /
• 1996

High spinal block is a rare complication during epidural block, but it may result in serious events. 56-year-old man with gall stones was scheduled for cholecystectomy under general anesthesia. After operation, lumbar epidural catheterization was done at $T_{8-9}$ interspace for postoperative pain control. At the recovery room, initial bolus drug (0.1% bupivacaine 10 ml containing fentanyl $100{\mu}g$) was administered via epidural catheter and observed carefully. 15 minutes later, hypotension and bradycardia ouccurred. Hartman' solution was administered rapidly and ephedrine 5 mg was injected. 30 minutes after drug administration, loss of consciousness and respiratory arrest developed. Tracheal intubation was done immediately. Cardiovascular and respiratory functions were monitored continuously. The location of intrathecal catheter was confirmed by cerebrospinal fluid (CSF) seen in syringe after aspiration of catheter. The patient recovered gradually and was placed in the ward 4 hours after drug administration, without any problems. He was discharged 1 week later in good health.

• 센서학회지
• /
• 제21권1호
• /
• pp.75-81
• /
• 2012

Optimizing the tapping time of a blast furnace is important to a stable operation and life extension. To optimize the tapping time of the blast furnace, the location of Hearth Liquid Level should be recognized. There are several ways to measure the hearth liquid level in the blast furnace, such as Electromotive Force(EMF) measurement, pressure measurement by putting in nitrogen probe and manometry with strain gauge. In this paper, it will be discussed using strain gauge among the three methods. Conventional strain gauge must be revised periodically. Since, internal pressure, temperature of internal refractory material and wind pressure have effect on the strain gauge. However, static pressure value is required to compensate. To solve these problems, this paper suggests finding relationship between Hearth Liquid Level and strain gauge output, adding digital filter in strain gauge. Using the proposed method, it was possible to estimate the hearth liquid level and determine the appropriate tapping time. Usefulness of the proposed method through simulations and experimental results are confirmed.

• Progress in Superconductivity
• /
• 제12권1호
• /
• pp.68-73
• /
• 2010

Y123 films have been deposited on $LaAlO_3$ (100) single-crystal and IBAD substrates by spray pyrolysis method using nitrate precursors. Ultrasonic atomization was adopted to decrease the droplet size, spraying angle and its moving velocity toward substrate for introducing the preheating tube furnace in appropriate location. A small preheating tube furnace was installed between spraying nozzle and substrate for fast drying and enhanced decomposition of precursors. C-axis oriented films were obtained on both LAO and IBAD substrates at deposition temperature of around $710{\sim}750^{\circ}C$ and working pressures of 10~15 torr. Thick c-axis epitaxial film with the thickness of $0.3{\sim}0.6\;{\mu}m$ was obtained on LAO single-crystal by 10 min deposition. But the XRD results of the film deposited on IBAD template at same deposition condition showed that the buffer layers of the IBAD metal substrate was affected by long residence of metal substrate at high temperature for YBCO deposition.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2014년도 추계학술대회 논문집
• /
• pp.314-320
• /
• 2014

Field balancing is required in any kind of phase information for the determination location balancing mass toward a rotor unbalance mass. Phase or phase angle is a measurement of the relationship of how one vibration signal which relates to another vibration signal and is commonly used to calculate the placement of balance weight. In this paper, A right guideline shows the photo optical speed sensor as the external keyphasor is a very useful when diagnosing machinery vibration problems on considering a phase lag comparing to the laser optical speed sensor. Some experimental results generate the interesting phase errors when appling to a wrong conditions. So, Usage of photo optical speed sensor which is used primarily to measure the shaft rotating speed serves as a reference for measuring vibration phase information has effect on the placement of phase angle how it was misunderstood. This paper will help a right method to search for the position of balancing weight and serves as baseline for further measurements using low cost and much easier user convenience. It is concluded that the propose baseline is likely to be applicable to apply to the practical field balancing weight.

• 한국소음진동공학회논문집
• /
• 제25권2호
• /
• pp.101-107
• /
• 2015

Field balancing is required in any kind of phase information for the determination location balancing mass toward a rotor unbalance mass. Phase or phase angle is a measurement of the relationship of how one vibration signal which relates to another vibration signal and is commonly used to calculate the placement of balance weight. In this paper, A right guideline shows the photo optical speed sensor as the external KeyPhasor is a very useful when diagnosing machinery vibration problems on considering a phase lag comparing to the laser optical speed sensor. Some experimental results generate the interesting phase errors when appling to a wrong conditions. So, Usage of photo optical speed sensor which is used primarily to measure the shaft rotating speed serves as a reference for measuring vibration phase information has effect on the placement of phase angle how it was misunderstood. This paper will help a right method to search for the position of balancing weight and serves as baseline for further measurements using low cost and much easier user convenience. It is concluded that the propose baseline is likely to be applicable to apply to the practical field balancing weight.

• Design & Manufacturing
• /
• 제2권4호
• /
• pp.48-53
• /
• 2008

We injection molded a thin type of plate and wedge type of plate with micro prizm patterns on its surface and investigated the fidelity of replication of the micro pattern depending on the process parameter such as mold temperature, melt temperature, injection rate or packing pressure. The size of the $90^{\circ}$ prizm pattern is $50{\mu}m$ and the size of the plate is about $335mm{\times}213mm$ and $400mm{\times}400mm$. The thicknesses are 2.6mm and 0.7mm at each edge of the wedge type of plate and 1mm at each edge of the thin type of plate. The fidelity of the replication turned out quite different according to the process parameters and location of the patterns on the plate. We measured the cavity pressure and temperature in real-time during the molding to analyze the effect of the local melt pressure and temperature on the micro pattern replication.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
• /
• pp.454-456
• /
• 1987

A more specialized area of transient evaluations is transmission line fault-detecting and protection system. During the first cycle or two following a power system fault, a high-speed protective relay is expected to make a decision as to the severity or location of the fault, usually based on 60 Hz information, i.e. the phase and magnitude of 60 Hz voltage or current signals. It is precisely at this time however that the signal is badly corrupted by noise, in the form of a de offset or frequencies above 50 Hz. One of several possible sources of transients in protection measuring signals is in the primary system for which protection is required in its response to the impact of short circuit fault on-set. Other sources are in the primary voltage and current transducers from which protection signals are derived, and, often of particular importance, in the interface circuits between the transducer secondaries and the comparator and measuring elements of the protection system. However, the noise signals that will be described in this paper are due to the main power system only and do not include errors due to current or voltage transducers.

• 한국전기전자재료학회논문지
• /
• 제18권11호
• /
• pp.996-1000
• /
• 2005

Experimental results are presented for the degradation of 3 nm-thick gate oxide $(SiO_2)$ under both Negative-bias Temperature Instability (NBTI) and Hot-carrier-induced (HCI) stresses using P and NMOSFETS, The devices are annealed with hydrogen or deuterium gas at high-pressure $(1\~5\;atm.)$ to introduce higher concentration in the gate oxide. Both interface trap and oxide bulk trap are found to dominate the reliability of gate oxide during electrical stress. The degradation mechanism depends on the condition of electrical stress that could change the location of damage area in the gate oxide. It was found the trap generation in the gate oxide film is mainly related to the breakage of Si-H bonds in the interface or the bulk area. We suggest that deuterium bonds in $SiO_2$ film are effective in suppressing the generation of traps related to the energetic hot carriers.