• The Journal of Korean Institute of Information Technology
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• v.16 no.11
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• pp.115-121
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• 2018

Fluorescent images using near-infrared light have no worry about radioactivity, and images can be checked in real time during surgery. Therefore experiments using fluorescent images for monitoring lymph node biopsy are actively under way. Fluorescent imaging equipment uses high heat-generating components such as LED and camera, thus uses water-cooling system as a stable heating suppression means. However in the fluorescent image equipment, the water cooling system takes a large volume which is a disadvantage in terms of miniaturization of the equipment. Even if the air cooling system is used for miniaturizing the equipment, heat generation is a problem. In this paper, we have experimented with the air cooling method using PWM control for the miniaturization of the equipment, and confirmed the constant quality of the fluorescent image and the suppression of the heat generation without any problems even when the equipment is used for a long time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.465-468
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• 2014

In this paper, we describe a method capable of measuring biological signals including respiration, heart rate, blood pressure, and blood sugar, using UWB (Ultra Wide Band) pulses, while does not contact the human body. Physiological signal is a basic data for checking the health. Because life is longer and active area of human becomes very broad, the medical system and the physical human resources which are focused on existing hospital must be located close patient, In that way, they hope be to engage in healthy life by stepping a quick step and treatment. Thus, it must be fitted closely to the patient. It is necessary to monitor the health without inconvenience on an ongoing basis. How to utilize radio waves in this way have been studied for a long time. However, the characteristics of radio waves on the human body has not been accurately grasped and developed as such. Accordingly, it is a level that can not be applied clinically. So, it is not widely put to practical use. In this paper, We analyzed and described the impact and characteristics of UWB pulses to the human body is a problem existing.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.576-581
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• 2021

In the post-epidemic era, COVID-19 has not yet been fully controlled. Wearing masks is still the main means of epidemic prevention, and the negative effects brought by masks continue to continue. Wearing a mask for a long time can cause two problems. The first problem is hypoxia, and the other is an increase in psychological stress. To reduce the negative impact of masks, this paper proposes a new breathing mode. It is the "Umm~" vocal breathing mode, which simultaneously solves the two problems of hypoxia and increased stress. This paper explores the reasons why new breathing patterns can relieve stress. Explains the relationship between HRV and stress index and uses SDNN as an indicator to detect stress index to confirm the effectiveness of this breathing pattern. Experimental results prove that the "Umm~" vocal breathing mode can not only relieve the stress induced by wearing a mask. And when not wearing a mask, it can also be used to relieve daily stress. This method that anyone can easily implement should be more popularized.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.2
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• pp.45-50
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• 2021

With the recent development of IT technology, research and interest in various bio-signal measuring devices are increasing. But studies related to ECG(electrocardiogram), which is one of the most representative bio-signals, particularly arrhythmic signal detection, are incomplete. Since arrhythmia has various causes and has a poor prognosis after onset, preventive treatment through early diagnosis is best. However, the 24-hour Holter electrocardiogram, a tool for diagnosing arrhythmia, has disadvantages in the limitation of use time, difficulty in analyzing motion artifact due to daily life, and the user's real-time alarm function in danger. In this study, an ECG and pulse monitoring device capable of continuous measurement for a long time, a real-time monitoring app, and software for analysis were developed, and the trend of the measured values was confirmed. In future studies, research on derivation of quantitative results of ECG signal measurement analysis is required, and further research on the development of an arrhythmic signal detection algorithm based on this is required.

• Journal of Periodontal and Implant Science
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• v.52 no.3
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• pp.242-257
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• 2022

Purpose: This study investigated periodontal ligament (PDL) restoration in osseointegrated implants using stem cells. Methods: Commercial pure titanium and zirconium oxide (zirconia) were coated with beta-tricalcium phosphate (β-TCP) using a long-pulse Nd:YAG laser (1,064 nm). Isolated bone marrow mesenchymal cells (BMMSCs) from rabbit tibia and femur, isolated PDL stem cells (PDLSCs) from the lower right incisor, and co-cultured BMMSCs and PDLSCs were tested for periostin markers using an immunofluorescent assay. Implants with 3D-engineered tissue were implanted into the lower right central incisors after extraction from rabbits. Forty implants (Ti or zirconia) were subdivided according to the duration of implantation (healing period: 45 or 90 days). Each subgroup (20 implants) was subdivided into 4 groups (without cells, PDLSC sheets, BMMSC sheets, and co-culture cell sheets). All groups underwent histological testing involving haematoxylin and eosin staining and immunohistochemistry, stereoscopic analysis to measure the PDL width, and field emission scanning electron microscopy (FESEM). The natural lower central incisors were used as controls. Results: The BMMSCs co-cultured with PDLSCs generated a well-formed PDL tissue that exhibited positive periostin expression. Histological analysis showed that the implantation of coated (Ti and zirconia) dental implants without a cell sheet resulted in a well-osseointegrated implant at both healing intervals, which was confirmed with FESEM analysis and negative periostin expression. The mesenchymal tissue structured from PDLSCs only or co-cultured (BMMSCs and PDLSCs) could form a natural periodontal tissue with no significant difference between Ti and zirconia implants, consequently forming a biohybrid dental implant. Green fluorescence for periostin was clearly detected around the biohybrid implants after 45 and 90 days. FESEM showed the invasion of PDL-like fibres perpendicular to the cementum of the bio-hybrid implants. Conclusions: β-TCP-coated (Ti and zirconia) implants generated periodontal tissue and formed biohybrid implants when mesenchymal-tissue-layered cell sheets were isolated from PDLSCs alone or co-cultured BMMSCs and PDLSCs.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.379-385
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• 2021

In order to synchronize a remote system time to the reference time like Coordinated Universal Time (UTC), it is required to compare the time difference between the two clocks. GNSS Precise Point Positioning (PPP) is one of the most general geodetic positioning methods and can be used for time and frequency transfer applications which require more precise time comparison performance than GNSS code. However, the PPP technique has a main drawback of day-boundary discontinuity which comes from the PPP model that the code measurements are applied to resolve the floating carrier-phase ambiguities. The Integer PPP (IPPP) technique is one of the methods which has been studied to compensate the day-boundary discontinuities exited in the conventional PPP. In this paper, we investigate the time and frequency capabilities of PPP and IPPP by using the measurement data obtained from two time transfer receivers which are closely located and using common reference 1 Pulse Per Second (PPS) and RF signals. From the experiment, it is investigated that the IPPP method can effectively compensate the day-boundary discontinuities without producing frequency offset. However, the PPP method can generating frequency offset which can severely degrade the time comparison performance with long-term period data.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.89-96
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• 2023

The Wiener-type nonlinear model where a static nonlinear block follows a dynamic linear block is widely used to describe the dynamics of chemical processes. A long process excitation step is typically needed to identify this Wiener-type nonlinear model with two blocks. In order to cope with this disadvantage, an identification method for the Wiener-type nonlinear model that uses only a single-step response is proposed here. The proposed method estimates the response of the dynamic linear sub-block from the initial part of the step response, and then the static nonlinear sub-block is identified. Because the only single-step response is used to identify the Wiener-type nonlinear model, there is great benefit in time and cost for obtaining process response. The performance of the proposed identification method with the single-step response is verified through a representative Wiener-type nonlinear process, a pH titration process, and a liquid level system.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.216-221
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• 2024

Ion cyclotron range of frequency (ICRF) heating system is an important auxiliary heating method in the experimental Advanced Superconducting Tokamak (EAST). In EAST, several megawatts of power are transmitted with coaxial transmission lines and coupled to the plasma. For the long pulse and high power operation of the ICRF waves heating system, it is very important to effectively control the power and initial phase of the ICRF signals. In this paper, a power and phase feedback control system is described based on field programmable gate array (FPGA) devices, which can realize complicated algorithms with the advantages of fast running and high reliability. The transmitted power and antenna phase are measured by a power and phase detector and digitized. The power and phase feedback control algorithms is designed to achieve the target power and antenna phase. The power feedback control system was tested on a dummy load and during plasma experiments. Test results confirm that the feedback control system can precisely control ICRF power and antenna phase and is robust during plasma variations.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.5
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• pp.353-362
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• 2016

Thermal barrier coating (TBC) is an essential element consisting of a super-alloy base and ceramic coating designed to achieve long operational time under a high temperature and pressure environment. However, the top coat of TBC can be delaminated at certain temperatures with long operation time. As the delamination of TBC is directly related to the blade damage, the coupling status of the TBC should be assured for reliable operation. Conventional studies of nondestructive evaluation have been made for detecting generation of thermally grown oxide (TGO) or qualitatively evaluating delamination in TBC. In this study, the ultrasonic C-scan method was developed to obtain the damage map inside TBC by estimating the delamination in a quantitative way. All specimens were isothermally degraded at $1,100^{\circ}C$ with different time, having different partial delamination area. To detect partial delamination in TBC, the C-scan was performed by a single transducer using pulse-echo method with normal incidence. Partial delamination coefficients of 1 mm to 6 mm were derived by the proportion of the surface reflection signal and flaw signal which were theoretical signals using Rogers-Van Buren and Kim's equations. Using the partial delamination coefficients, the partial delamination maps were obtained. Regardless of the partial delamination coefficient, partial delamination area was increased when degradation time was increased in TBC. In addition, a decrease in partial delamination area in each TBC specimen was observed when the partial delamination coefficient was increased. From the portion of the partial delamination maps, the criterion for delamination was derived.

• The Korean Journal of Pain
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• v.33 no.2
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• pp.99-107
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• 2020

Chronic severe pain results in a detrimental effect on the patient's quality of life. Such patients have to take a large number of medications, including opioids, often without satisfactory effect, sometimes leading to medication abuse and the pain worsening. Spinal cord stimulation (SCS) is one of the most effective technologies that, unlike other interventional pain treatment methods, achieves long-term results in patients suffering from chronic neuropathic pain. The first described mode of SCS was a conventional tonic stimulation, but now the novel modalities (high-frequency and burst), techniques (dorsal root ganglia stimulations), and technical development (wireless and implantable pulse generator-free systems) of SCS are becoming more popular. The improvement of SCS systems, their miniaturization, and the appearance of new mechanisms for anchoring electrodes results in a significant reduction in the rate of complications and revision surgeries, and the appearance of new waves of stimulation allows not only to avoid the phenomenon of addiction, but also to improve the long-term results of chronic SCS. The purpose of this review is to describe the current condition of SCS and up-to-date technical advances.