• Radiation Oncology Journal
• /
• v.32 no.4
• /
• pp.256-261
• /
• 2014

Purpose: We performed invasive thermometry to verify the elevation of local temperature in the liver during hyperthermia. Materials and Methods: Three 40-kg pigs were used for the experiments. Under general anesthesia with ultrasonography guidance, two glass fiber-optic sensors were placed in the liver, and one was placed in the peritoneal cavity in front of the liver. Another sensor was placed on the skin surface to assess superficial cooling. Six sessions of hyperthermia were delivered using the Celsius TCS electro-hyperthermia system. The energy delivered was increased from 240 kJ to 507 kJ during the 60-minute sessions. The inter-session cooling periods were at least 30 minutes. The temperature was recorded every 5 minutes by the four sensors during hyperthermia, and the increased temperatures recorded during the consecutive sessions were analyzed. Results: As the animals were anesthetized, the baseline temperature at the start of each session decreased by $1.3^{\circ}C$ to $2.8^{\circ}C$ (median, $2.1^{\circ}C$). The mean increases in temperature measured by the intrahepatic sensors were $2.42^{\circ}C$ (95% confidence interval [CI], 1.70-3.13) and $2.67^{\circ}C$ (95% CI, 2.05-3.28) during the fifth and sixth sessions, respectively. The corresponding values for the intraperitoneal sensor were $2.10^{\circ}C$ (95% CI, 0.71-3.49) and $2.87^{\circ}C$ (1.13-4.43), respectively. Conversely, the skin temperature was not increased but rather decreased according to application of the cooling system. Conclusion: We observed mean $2.67^{\circ}C$ and $2.87^{\circ}C$ increases in temperature at the liver and peritoneal cavity, respectively, during hyperthermia. In vivo real-time thermometry is useful for directly measuring internal temperature during hyperthermia.

• Journal of Biomedical Engineering Research
• /
• v.38 no.6
• /
• pp.277-284
• /
• 2017

This paper presents an implantable pH measurement electrode for wireless gastroesophageal reflux measurement. Usually, gastroesophageal reflux is diagnosed by a catheter-type wire connection between the esophagus and the diagnostic device which brings many side effects such as restriction of daily living, pain, and discomfort in the nasal cavity and pharynx of patients. In order to solve these issues, researchers have been studied a wireless measurement method and a micro-sized pH electrode for human body insertion is necessary. Commercial glass packaged pH meter is formed by a sensing and a reference electrodes in a KCl solution. However, if the glass meter is inserted into the human body, there are risks of leakage of the solution, breakage of the glass package, injury of the body elements. Therefore, the solution should be solidified on the micro-sized noble metal wire which has a characteristic of biocompatible. After solidified wire fabrication, the designed meter was tested for feasibility of measurement and the result was well agreed with pH values of commercial pH meter. Potentials in pH 1 to 12 solution was measured to obtain the sensitivity of the sensor with linearity. And we have designed a simulation of gastroesophageal reflux with symptom frequency, interval, and duration time in pH 2 solution. The proposed sensor has capable to get the same potential for 24 measurements in 3 days, and it has sensed same pH values of 2 for one hour with every 10 minutes. Furthermore, the sensor was survived for 48 hours with reasonable potentials in the acid solution.

• Korean Journal of Optics and Photonics
• /
• v.29 no.6
• /
• pp.241-246
• /
• 2018

In this paper, a low-cost optical temperature sensor is implemented, using a fiber Bragg grating (FBG) as the temperature probe and a low-cost VCSEL with temperature-dependent output wavelength as the light source. To analyze the wavelength of the reflected light from the FBG, an interrogation was applied using a method of referring to the internal temperature according to the output wavelength of the VCSEL. When the temperature of the VCSEL was adjusted from 14 to $52.2^{\circ}C$, the output wavelength varied from 1519.90 to 1524.25 nm. The degree of wavelength tuning according to temperature was $0.114nm/^{\circ}C$. The variable wavelength repeatability error according to temperature was ${\pm}0.003nm$, and the temperature measurement error was ${\pm}0.18^{\circ}C$. As a result of measuring the temperatures from 22.3 to $194.2^{\circ}C$, the value of the internal temperature change of the light source according to the applied temperature ${\Delta}T$ was $0.146^{\circ}C/{\Delta}T$, the change in reflected wavelength of the temperature probe according to applied temperature ${\Delta}T$ was measured at $16.64pm/^{\circ}C$. and the temperature measurement error of the sensor was ${\pm}1^{\circ}C$.

• The Korean Journal of Ceramics
• /
• v.7 no.1
• /
• pp.36-40
• /
• 2001

In order to fabricate uncooled IR sensors for pyroelectric applications, multilayered thin films of Pt/PbTiO$_3$/Pt/Ti/Si$_3$N$_4$/SiO$_2$/Si and thermally isolating membrane structures of square-shaped/cantilevers-shaped microstructures were prepared. Cavity was also fabricated via direct silicon wafer bonding and etching technique. Metallic Pt layer was deposited by ion beam sputtering while PbTiO$_3$ thin films were prepared by sol-gel technique. Micromachining technology was used to fabricate microstructured-membrane detectors. In order to avoid a difficulty of etching active layers, silicon-nitride membrane structure was fabricated through the direct bonding and etching of the silicon wafer. Although multilayered thin film deposition and device fabrications were processed independently, these could b integrated to make IR micro-sensor devices.

• Journal of Sensor Science and Technology
• /
• v.29 no.5
• /
• pp.354-359
• /
• 2020

The high vacuum hermetic sealing technique ensures excellent performance of MEMS resonators. For the high vacuum hermetic sealing, the customization of anodic bonding equipment was conducted for the glass/Si/glass triple-stack anodic bonding process. Figure 1 presents the schematic of the MEMS resonator with triple-stack high-vacuum anodic bonding. The anodic bonding process for vacuum sealing was performed with the chamber pressure lower than 5 × 10^-6 mbar, the piston pressure of 5 kN, and the applied voltage was 1 kV. The process temperature during anodic bonding was 400 ℃. To maintain the vacuum condition of the glass cavity, a getter material, such as a titanium thin film, was deposited. The getter materials was active at the 400 ℃ during the anodic bonding process. To read out the electrical signals from the Si resonator, a vertical feed-through was applied by using through glass via (TGV) which is formed by sandblasting technique of cap glass wafer. The aluminum electrodes was conformally deposited on the via-hole structure of cap glass. The TGV process provides reliable electrical interconnection between Si resonator and aluminum electrodes on the cap glass without leakage or electrical disconnection through the TGV. The fabricated MEMS resonator with proposed vacuum packaging using three-layer anodic bonding process has resonance frequency and quality factor of about 16 kHz and more than 40,000, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.7
• /
• pp.516-520
• /
• 2012

In this paper, we have theoretically analyzed and designed a dielectric multi-layer sensor with a SPR (surface plasmon resonance) using analytical calculation and FDTD (finite difference time-domain) methods. The proposed structure is composed of periodic layer and thin metal film. It has many advantages. One of that is a high sensitivity of the SPR. Another is a high Q-factor of the characteristics in the PhC (photonic crystals) micro-cavity structure. The incident light has double resonance characteristics, because the filtered light by PhC structure, dielectric multi-layer, is met the thin metal film for SPR effect. We have also observed the change of resonance characteristics according to the variation of effective index on the metal film.

• Journal of the Korean Society for Precision Engineering
• /
• v.33 no.1
• /
• pp.23-29
• /
• 2016

In this paper, a real-time condition diagnosis system for the lens injection molding process is developed through the use of LabVIEW. The built-in-sensor (BIS) mold, which has pressure and temperature sensors in their cavities, is used to capture real-time signals. The measured pressure and temperature signals are processed to obtain features such as maximum cavity pressure, holding pressure and maximum temperature by the feature extraction algorithm. Using those features, an injection molding condition diagnosis model is established based on a response surface methodology (RSM). In the real-time system using LabVIEW, the front panels of the data loading and setting, feature extraction and condition diagnosis are realized. The developed system is applied in a real industrial site, and a series of injection molding experiments are conducted. Experimental results show that the average real-time condition diagnosis rate is 96%, and applicability and validity of the developed real-time system are verified.

• Journal of Sensor Science and Technology
• /
• v.14 no.4
• /
• pp.211-218
• /
• 2005

As the cause and the treatment about gastrointestinal disease has been issued recently, the importance of measuring the pressure in the gastrointestinal tract has been increased. However, the conventional measurement methods of the pressure in the gastrointestinal tract cause the patients' pain and inconvenience as well as an inaccurate pressure measurement. In this paper, the pressure monitoring telemetry system has been designed and implemented for an accurate pressure measurement inside the gastrointestinal tract with minimizing pain and inconvenience. The pressure monitoring telemetry system is composed of a pressure measurement capsule and an external receiver. The capsule has been miniaturized into the same size of a vitamin tablet so that the capsule can be swallowed through the oral cavity. After the capsule acquires and encodes the pressure data in the gastrointestinal tract, the encoded pressure data are modulated by frequency shift keying (FSK) and transmitted with ultrahigh frequency (UHF) band signal to the outside of a body. The performance of the telemetry capsule for monitoring pressure in the gastrointestinal tract is demonstrated by the results of animal in-vivo experiments.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.3
• /
• pp.403-408
• /
• 2008

The gyroscope is the sensor for detecting the rotation in inertial reference frame and constitute the navigation system together an accelerometer. As the inertial reference equipment for attitude determination and control in the satellite, the mechanical gyroscope has been used but it bring the disturbance for mass unbalance so the disturbance give a bad influence to the observation satellite mission because the mechanical gyroscope has the rotation parts. During the launch. The mechanical gyroscope is weak in vibration, shock and has the defect of narrow operating temperature range so it need the special design in integration. Recently the low orbit observation satellite for seeking the high pointing accuracy of image camera payload accept the FOG(Fiber Optic Gyro) or RLG(Ring Laser Gyro) for the attitude determination and control. The Ring Laser Gyro makes use of the Sanac effect within a resonant ring cavity of a He-Ne laser and has more accuracy than the other gyros. It need the 1000V DC to create the He-Ne plasma in discharge tube. In this paper, the design process of the High Voltage Power Supply for RLG(Ring Laser Gyroscope) is described. The specification for High Voltage Power Supply (HVPS) is proposed. Also, The analysis of flyback converter topology is explained. The Design for the HVPS is composed of the inverter circuit, feedback control circuit, high frequency switching transformer design and voltage doubler circuit.

• ETRI Journal
• /
• v.30 no.5
• /
• pp.747-749
• /
• 2008

We introduce a pixel-structured scintillator realized on a flexible polymeric substrate and demonstrate its feasibility as an X-ray converter when it is coupled to photosensitive elements. The sample was prepared by filling $Gd_2O_2S:Tb$ scintillation material into a square-pore-shape cavity array fabricated with polyethylene. For comparison, a sample with the conventional continuous geometry was also prepared. Although the pixelated geometry showed X-ray sensitivity of about 58% compared with the conventional geometry, the resolving power was improved by about 70% above a spatial frequency of 3 $mm^{-1}$. The spatial frequency at 10% of the modulation-transfer function was about 6 $mm^{-1}$.