• Journal of the Korean institute of surface engineering
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• v.33 no.4
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• pp.217-221
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• 2000

The gate oxide thickness is becoming thinner and thinner in order to speed up the semiconductor CMOS devices. We have investigated very thin$ SiO_2$ gate oxide layers and found anomaly between the thickness determined with capacitance measurement and these obtained with cross-sectional high resolution transmission electron microscopy. The thicknesses difference of the two becomes important for the thickness of the oxide below 5nm. We propose that the variation of dielectric constant in thin oxide films cause the anomaly. We modeled the behavior as (equation omitted) and determined $\varepsilon_{bulk}$=3.9 and $\varepsilon_{int}$=-4.0. We predict that optimum $SiO_2$ gate oxide thickness may be $20\AA$ due to negative contribution of the interface dielectric constant. These new results have very important implication for designing the CMOS devices.s.

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.333-339
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• 1997

We fabricated a sensor head which consists of spliced different-diameter fiber gratings for discrimination between strain and temperature. Because the fibers were drawn from the same preform, their temperature characteristics were the same but not for strain sensitivities which are inversely proportional to fibers cross-sectional areas. In measurement range of 0-1500$\mu$strain and 20-10$0^{\circ}C$, we could obtain, by using the matrix calculation, the unknown physical quantities within 10% of calculation error compared with the micrometer and thermocouple values. To improve the strain measurement accuracy, we suggest a new, novel method which deploys an unbalanced fiber Mach-Zehnder interferometer. This new signal processing technique converts the strain information to interference signal amplitude variation, temperature-independently. we obtained measurement accuracy nearly 80 times better than that obtainable with the conventional optical spectrum analyzer usage.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.50-50
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• 2000

In this paper, a new measuring system is :proposed which can measure the fine 6-DOF displacement of rigid bodies. Its measurement principle is based on detection of laser beam reflected from a specially fabricated mirror that looks like a triangular pyramid having an equilateral cross-sectional shape. The mirror has three lateral reflective surfaces inclined 45$^{\circ}$ to its bottom surface. We call this mirror 3-facet mirror. The 3-facet mirror is mounted on the object whose 6-DOF displacement is to be measured. The measurement is operated by a laser-based optical system composed of a 3-facet mirror, a laser source, three position-sensitive detectors(PSD). In the sensor system, three PSDs are located at three corner points of a triangular formation, which is an equilateral triangular formation tying parallel to the reference plane. The sensitive areas of three PSDs are oriented toward the center point of the triangular formation. The object whose 6-DOF displacement is to be measured is situated at the center with the 3-facet mirror on its top surface. A laser beam is emitted from the laser source located at the upright position and vertically incident on the top of the 3-fatcet mirror. Since each reflective facet faces toward each PSD, the laser beam is reflected at the 3-facet mirror and splits into three sub-beams, each of which is reflected from the three facets and finally arrives at three PSDs, respectively. Since each PSD is a 2-dimensional sensor, we can acquire the information on the 6-DOF displacement of the 3-facet mirror. From this principle, we can get 6-DOF displacement of any object simply by mounting the 3-facet mirror on the object. In this paper, we model the relationship between the 6-DOF displacement of the object and the outputs of three PSDs. And, a series of simulations are performed to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects.

• The Journal of Korean Physical Therapy
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• v.23 no.4
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• pp.59-66
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• 2011

Purpose: The objective of this study was to evaluate the inter- and intra-examiner reliability of ultrasonography (US) for measuring the thicknesses and cross-sectional area of the longus colli muscle (LCM) in healthy subjects. Methods: Twenty-five healthy adults participated in this study as subjects and two examiners attended to the study. LCM size was measured at the level of the thyroid cartilage. All subjects were randomly allocated to one of the three different methods. Method 1 was that the examiner A conducts the first measurement and one hour later conducts the second measurement and twenty four hours later conducts the third measurement, respectively. Method 2 was that the examiner B conducts the measurements in the same way as the examiner A. Method 3 was that the examiners A and B randomly conduct the measurements twice at an interval of one hour. Results: The intra-class correlation coefficient (ICC) for the intra-examiner reliability ranged from 0.78 to 0.98 at rest and 0.57 to 0.98 during contraction for the examiner A. The $ICC_{3,3}$ for the intra-examiner reliability ranged from 0.60 to 0.96 at rest and 0.57 to 0.92 during contraction for the examiner B. The $ICC_{2,3}$ for the inter-examiner reliability ranged from 0.80 to 0.91 at rest and 0.84 to 0.93 during contraction. Conclusion: The findings of this study indicate that US is a reliable method for measuring the LCM size.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.893-904
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• 2020

The study examines the relationship between credit risk and operational risk (understanding of risk management, risk identification, risk assessment and control, and risk monitoring) on risk management practices followed by private and public sector commercial banks. The cross-sectional data method was used to check the impact of risk management practices. Data was collected from the bank employees and a total of 284 respondents were finally selected for further analysis. Measurement Invariance of Composite Models analysis is used to test the quality of the measurement model for sub-samples, and multi-group analysis is used for path analysis in sub-sample through PLS-SEM. The findings of the study as the total sample show that both types of banks are managing adequate and significant risk management practices. On the other hand, sub-groups' results show private sector banks are more momentous than public sector banks. Risk identification is significantly different at the sub-group level, which shows public sector banks are more concentrating on this type of risk. Understanding of risk management has no significant effect on both types of banks and risk assessment & control for public sector banks, and there is a difference in the risk management practices among private and public sector commercial banks.

• The Korean Journal of Pain
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• v.33 no.1
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• pp.54-59
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• 2020

Background: The median nerve cross-sectional area (MNCSA) is a useful morphological parameter for the evaluation of carpal tunnel syndrome (CTS). However, there have been limited studies investigating the anatomical basis of median nerve flattening. Thus, to evaluate the connection between median nerve flattening and CTS, we carried out a measurement of the median nerve thickness (MNT). Methods: Both MNCSA and MNT measurement tools were collected from 20 patients with CTS, and from 20 control individuals who underwent carpal tunnel magnetic resonance imaging (CTMRI). We measured the MNCSA and MNT at the level of the hook of hamate on CTMRI. The MNCSA was measured on the transverse angled sections through the whole area. The MNT was measured based on the most compressed MNT. Results: The mean MNCSA was 9.01 ± 1.94 ㎟ in the control group and 6.58 ± 1.75 ㎟ in the CTS group. The mean MNT was 2.18 ± 0.39 mm in the control group and 1.43 ± 0.28 mm in the CTS group. Receiver operating characteristics curve analysis demonstrated that the optimal cut-off value for the MNCSA was 7.72 ㎟, with 75.0% sensitivity, 75.0% specificity, and an area under the curve (AUC) of 0.82 (95% confidence interval [CI], 0.69-0.95). The best cut off-threshold of the MNT was 1.76 mm, with 85% sensitivity, 85% specificity, and an AUC of 0.94 (95% CI, 0.87-1.00). Conclusions: Even though both MNCSA and MNT were significantly associated with CTS, MNT was identified as a more suitable measurement parameter.

• Journal of Wetlands Research
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• v.8 no.4
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• pp.59-67
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• 2006

In this study, dilution discharge method to measure streamflow using water quality data at small streams during low flow season was applied and compared with the conventional method using flowmeter combined with cross-sectional measurement. Streamflow were measured using both methods in Dal-cheon around Naesok Wastewater Treatment Plant located in Boeun, Chugbuk. This stream is reported to suffer from excessive algal growth in spring. An average flowrate difference of $0.004m^3/sec$ was obtained between the two methods. Once further tested for various conditions, the simple water quality method suggested in this study can be used effectively to estimate stream flowrates during low flow seasons where no measuring facilities such as weirs and flowmeters are not available or water depths are too small to measure flow velocities and exact cross-sections.

• Journal of Ocean Engineering and Technology
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• v.35 no.4
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• pp.266-272
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• 2021

Mooring systems are among the most important elements employed to control the motion of floating offshore structures on the sea. Considering the use of polymer material, a new method is proposed to address the creep characteristics rather than the method of using a tension load cell for measuring the tension of the mooring line. This study uses a synthetic mooring rope made from a polymer material, which usually consists of three parts: center, eye, and splice, and which makes a joint for two successive ropes. We integrate the optical sensor into the synthetic mooring ropes to measure the rope tension. The different structure of the mooring line in the longitudinal direction can be used to measure the loads with the entire mooring configuration in series, which can be defined as SMART (Smart Mooring and Riser Truncation) mooring. To determine the characteristics of the basic SMART mooring, a SMART mooring with a diameter of 3 mm made of three different polymer materials is observed to change the wavelength that responds as the length changes. By performing the longitudinal tension experiment using three different SMART moorings, it was confirmed that there were linear wavelength changes in the response characteristics of the 3-mm-diameter SMART moorings. A 54-mm-diameter SMART mooring is produced to measure the response of longitudinal tension on the center, eye, and splice of the mooring, and a longitudinal tension of 100 t in step-by-step applied for the Maintained Test and Fatigue Cycle Test is conducted. By performing a longitudinal tension experiment, wavelength changes were detected in the center, eye, and splice position of the SMART moorings. The results obtained from each part of the installed sensors indicated a different strain measurement depending on the position of the SMART moorings. The variation of the strain measurement with the position was more than twice the result of the difference measurement, while the applied external load increased step-by-step. It appears that there is a correlation with an externally generated longitudinal tensional force depending on the cross-sectional area of each part of the SMART mooring.

• Journal of ILASS-Korea
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• v.28 no.1
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• pp.1-9
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• 2023

In the cylinder of gasoline direct injection engines, the spray targeting from injectors is of great significance for fuel consumption and pollutant emissions. The automotive industry is putting a lot of effort into improving injector targeting accuracy. To improve the targeting accuracy of injectors, it is necessary to develop models that can predict the spray targeting positions. When developing spray targeting models, the most used technique is computational fluid dynamics (CFD). Recently, due to the superiority of machine learning in prediction accuracy, the application of machine learning in this field is also receiving constant attention. The purpose of this study is to build a machine learning model that can accurately predict spray targeting based on the design parameters of injectors. To achieve this goal, this study firstly used laser sheet beam visualization equipment to obtain many spray cross-sectional images of injectors with different parameters at different injection pressures and measurement planes. The spray images were processed by MATLAB code to get the targeting coordinates of sprays. A total of four models were used for the prediction of spray targeting coordinates, namely ANN, LSTM, Conv1D and Conv1D & LSTM. Features fed into the machine learning model include injector design parameters, injection conditions, and measurement planes. Labels to be output from the model are spray targeting coordinates. In addition, the spray data of 7 injectors were used for model training, and the spray data of the remaining one injector were used for model performance verification. Finally, the prediction performance of the model was evaluated by R² and RMSE. It is found that the Conv1D&LSTM model has the highest accuracy in predicting the spray targeting coordinates, which can reach 98%. In addition, the prediction bias of the model becomes larger as the distance from the injector tip increases.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.2
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• pp.37-42
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• 2000

The comparative study of texture of Al/Ti thin films deposited on low-dielectric polymer and $SiO_2$substrates has been investigated. Fifty-nm-thick Ti films and 500-nm-thick Al-1%Si-0.5%Cu (wt%) films were deposited sequentially onto low-k polymers and $SiO_2$by using a DC magnetron sputtering system. The texture of Al thin film was determined using X-ray diffraction (XRD) theta-2theta ($\theta$-2$\theta$) and rocking curve and the microstructure of Al/Ti films on low-k polymer and $SiO_2$substrates was characterized by cross-sectional transmission electron microscopy (TEM). Both the $\theta$-2$\theta$ method and rocking curve measurement suggest that Al/Ti thin films deposited on $SiO_2$have stronger texture than those deposited on low-k polymer. The texture of Al thin films strongly depended on that of Ti films. Cross-sectional TEM revealed that grains of Ti films on $SiO_2$substrates had grown perpendicular to the substrate, while the grains of Ti alms on SiLK substrates were formed randomly. The lower degree of (111) texture of Al thin films on low-k polymer was due to Ti underlayer.