• Journal of the Korean Institute of Telematics and Electronics
• /
• v.21 no.5
• /
• pp.90-99
• /
• 1984

A onetimensional distribution of the temperature and the heat source in the SOI (silicon-on-insulator) multi-layer structure illuminated by tungsten lamps from both sides was obtained by solving the heat equation in steady state on a finite difference grid using successive over-relaxation method. The heat source distribution was obtained by considering such features as spectral components of the light source, multiple reflection at the internal interfaces, temperature and frequency dependence of the light absorption coefficient, etc. The front and back surface temperatures, which are boundary conditions for the heat equation, were derived from a requirement that they satisfy the radiation conditions. The radiation flux as well as the conduction flux was considered in modelling the thermal behaviour at the internal interfaces. Since the temperature and the heat source profiles are strongly dependent upon each other, the calculation of each profile was iterated using the updated profile of the other until they are consistent with each other. The experimental temperature at the front surface of the wafer as measured by Pyrometer was about 1200$^{\circ}$K, while the simulated temperature was 1120$^{\circ}$K.

• Journal of Sensor Science and Technology
• /
• v.5 no.5
• /
• pp.69-77
• /
• 1996

In this paper, we fabricated the micro hotplate which consisted of a thin film heater(Pt/Cr bilayers) sandwiched with the thermal oxide and E-beam evaporated oxide. And we studied the electrical and the structural properties of Pt/Cr bilayers due to annealing temperature. When we compared the temperature measured from type k thermocouples with the temperature acquired from I.R. thermo-vision system according to the variations of emissivity, the emissivity of I-beam evaporated oxide was 0.5. The sheet resistance of Pt/Cr bilayers didn't depend on the Cr layer thickness, and it was considered as the existence of CrO between the Pt and the Cr layer. When the annealing temperature was increased from $500^{\circ}C$ to $700^{\circ}C$, the out-diffusions of Cr were increased(which was confirmed by AES depth profile) and the grain size of Pt(220) phase was enlarged also(analyzed by XRD and SEM photographs). From the results of XRD analysis and AES depth profile, the Pt/Cr bilayers annealed at $500^{\circ}C$ were more stable than any other cases in structural properties.

• Food Science of Animal Resources
• /
• v.44 no.4
• /
• pp.790-804
• /
• 2024

This study compared the physicochemical properties of edible insect oils from silkworm (Bombyx mori) pupa (SP), sago palm weevil (Rhynchophorus ferrugineus) larva (PW), and bamboo caterpillar (Omphisa fuscidentalis; BC) to oils from chicken skin (CK), beef back fat (BF), pork back fat (PF), salmon belly (SB), sea bass belly (BB), coconut (C), and peanut (P). The fatty acid profiles and thermal behaviors (crystallization and melting) of the extracted oils were evaluated. PW and BC oils had more saturated fatty acids (SFAs) than CK, PF, SB, BB, and P oils. SP oil had equivalent SFA content to CK and BB oils. Insect oils exhibited similar monounsaturated fatty acid concentrations in all samples, except C oils. PW and BC oils exhibited a higher content of palmitoleic acid than the other oils. SP oils contained polyunsaturated fatty acids similar to those in SB and BB oils, which were higher than those in PW, BC, CK, BF, and PF oils. SP oil also exhibited the highest concentration of α-linolenic acid (C18:3 n-3). Arachidonic acid (0.01-0.02 g/100 g) in all insect oils was lower level compared to CK, BF, PF, SB, and BB oils. SP oil (0.03 g/100 g) exhibited a slightly higher level of eicosapentaenoic acid compared to PW (0.01 g/100 g) and BC (0.01 g/100 g) oils. The insect oils were liquid at ambient temperature, solid below -15℃, and required less energy (∆H_m-max) for melting than other samples. This study indicated that insects, particularly SP, could serve as an alternative source of fat to meet its growing demand.

• Radiation Oncology Journal
• /
• v.7 no.2
• /
• pp.313-320
• /
• 1989

In capacitive heating device, which considered efficient for deep heating, parallel arrangement of the electrodes is a serious limiting factor in heating for eccentrically located lesions because it causes overheating of the exposed ipsilateral skin surface, the heating pattern is also frequently inappropriate, and the arrangement tends to be unstable due to the patient's gravity. Therefore we attempted an angular arrangement of the electordes to achieve more homogenous and efficient heating for such lesions. In phantom study, both the thermal profile and thermogram established the heating pattern in this unusual angular arrangement of the electrodes at $60^{\circ},\;90^{\circ}\; and\;120^{\circ}$ angles, respectively. An angular arrangement was also clinically applied to 3 patients. The patients' tolerance was good without significant complication and the thermal distribution was satisfactory. In conclusion, this unusual arrangement of electrodes appears to be promising in the clinical application to the eccentrically located lesions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.242-242
• /
• 2006

Increasingly complex tasks are performed by computers or cellular phone, requiring more and more memory capacity as well as faster and faster processing speeds. This leads to a constant need to develop more highly integrated circuit systems. Therefore, there have been numerous studies by many engineers investigating circuit patterning. In particular, PCB including module/package substrates such as FCB (Flip Chip Board) has been developed toward being low profile, low power and multi-functionalized due to the demands on miniaturization, increasing functional density of the boards and higher performances of the electric devices. Imprint lithography have received significant attention due to an alternative technology for photolithography on such devices. The imprint technique. is one of promising candidates, especially due to the fact that the expected resolution limits are far beyond the requirements of the PCB industry in the near future. For applying imprint lithography to FCB, it is very important to control thermal properties and mechanical properties of dielectric materials. These properties are very dependent on epoxy resin, curing agent, accelerator, filler and curing degree(%) of dielectric materials. In this work, the epoxy composites filled with silica fillers and cured with various accelerators having various curing degree(%) were prepared. The characterization of the thermal and mechanical properties wasperformed by thermal mechanical analysis (TMA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), rheometer, an universal test machine (UTM).

• Bulletin of the Korean Chemical Society
• /
• v.35 no.11
• /
• pp.3319-3325
• /
• 2014

Eu(III)-doped $CeO_2$ nanorods were prepared by a co-precipitation method at room temperature, and their photoluminescence profiles were examined with different Eu(III)-doping concentrations and thermal annealing temperatures. Scanning electron microscopy, X-ray diffraction crystallography and UV-Vis absorption spectroscopy were employed to examine the morphology, crystal structure and photon absorption profiles of the nanorods, respectively. Additionally, their 2D and 3D-photoluminescence profile maps were obtained to fully understand the photoluminescence mechanism. We found that the magnetic dipole $^5D_0{\rightarrow}^7F_1$ and the electric dipole $^5D_0{\rightarrow}^7F_2$ transitions of Eu(III) were highly dependent on the doping concentration, annealing temperature and excitation wavelength, which was explained by the presence of different Eu(III)-doping sites (with and without an inversion center) in the $CeO_2$ host with a cubic crystal structure.

• Nuclear Engineering and Technology
• /
• v.40 no.6
• /
• pp.477-488
• /
• 2008

The objective of the paper is to analyze the thermally induced density wave oscillations in water cooled boiling water reactors. A transient thermal hydraulic model is developed with a characteristics-based implicit finite-difference scheme to solve the nonlinear mass, momentum and energy conservation equations in a time-domain. A two-phase flow was simulated with a one-dimensional homogeneous equilibrium model. The model treats the boundary conditions naturally and takes into account the compressibility effect of the two-phase flow. The axial variation of the heat flux profile can also be handled with the model. Unlike the method of characteristics analysis, the present numerical model is computationally inexpensive in terms of time and works in a Eulerian coordinate system without the loss of accuracy. The model was validated against available benchmarks. The model was extended for the purpose of studying the flow-induced density wave oscillations in forced circulation and natural circulation boiling water reactors. Various parametric studies were undertaken to evaluate the model's performance under different operating conditions. Marginal stability boundaries were drawn for type-I and type-II instabilities in a dimensionless parameter space. The significance of adiabatic riser sections in different boiling reactors was analyzed in detail. The effect of the axial heat flux profile was also investigated for different boiling reactors.

• Nuclear Engineering and Technology
• /
• v.49 no.4
• /
• pp.781-786
• /
• 2017

The presence of crust on the inner walls of metallic ducts impairs transportation because crust completely or partially hinders the passage of fluid to the processing unit and causes damage to equipment connected to the production line. Its localization is crucial. With the development of the electronic imaging system installed at the Argonauta/Nuclear Engineering Institute (IEN)/National Nuclear Energy Commission (CNEN) reactor, it became possible to visualize crust in the interior of metallic piping of small diameter using real-time neutron radiography images obtained with a low neutron flux. The obtained images showed the resistance offered by crust on the passage of water inside the pipe. No discrepancy of the flow profile at the bottom of the pipe, before the crust region, was registered. However, after the passage of liquid through the pipe, images of the disturbances of the flow were clear and discrepancies in the flow profile were steep. This shows that this technique added the assembled apparatus was efficient for the visualization of the crust and of the two-phase flows.

• Advances in aircraft and spacecraft science
• /
• v.8 no.4
• /
• pp.289-302
• /
• 2021

Ensuring flight safety for passengers as well as crew is the most important aspect of modern aviation, and in order to achieve this, it is necessary to be able to forecast the durability of individual components. The present contribution illustrates the results of a computational analysis to determine the possibility of analysing the prediction of bearing durability in on-board rotating equipment from the point of view of thermal fatigue.In this study, a method developed at the Air Force Institute of Technology was used for analysis, which allowed to determine the bearing durability from the flight altitude profile. Two aircraft have been chosen for analysis - a military M-28 and a civilian Embraer. As a result of the analysis were obtained: the bearing durability in on-board rotating devices, average operation time between failures, as well as failure rate. In conclusion, the practical applicability of this approach is demonstrated by the fact that even with a limited number of flight parameters, it is possible to estimate bearing durability and increase flight safety by regular inspections.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.6
• /
• pp.535-540
• /
• 2022

DC-link capacitors are reliability-critical components in a photovoltaic (PV) inverter. Typically, the lifetime of a DC-link capacitor is evaluated by considering the voltage and hot-spot temperature of the capacitor under the specific operating condition of the PV inverter. However, the output of the PV inverter is determined by solar irradiation and ambient temperature, which vary with the seasons; accordingly, the hot-spot temperature of the capacitor also changes. Therefore, the mission profile of the PV system should be considered to effectively evaluate the reliability of the DC-link capacitor. In this study, the reliability of the DC-link capacitor of a three-level NPC inverter is comparatively analyzed with and without considering the mission profiles of the PV system, where two mission profiles recorded in Arizona and Iza are considered. The accumulated damage of the DC-link capacitor is calculated based on the lifetime model by analyzing its thermal loading. Afterward, a reliability evaluation of the DC-link capacitor is performed at the component level and then at the system level by considering all capacitors by means of Monte Carlo analysis. Results reveal the importance of performing a mission-profile-based reliability evaluation during the design of high-reliability PV inverters to achieve the target reliability performance.