• 한국재료학회지
• /
• 제29권8호
• /
• pp.469-476
• /
• 2019

A lead-free bulk ceramic having a chemical formula $Ba_{0.8}Ca_{0.2}(Ti_{0.8}Zr_{0.1}Ce_{0.1})O_3$ (further termed as BCTZCO) is synthesized using mixed oxide route. The structural, dielectric, impedance, and conductivity properties, as well as the modulus of the synthesized sample are discussed in the present work. Analysis of X-ray diffraction data obtained at room temperature reveals the existence of some impurity phases. The natural surface morphology shows close packing of grains with few voids. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes on impedance and capacitive characteristics, (b) relationship between properties and crystal structure, and (c) nature of the relaxation mechanism of the prepared samples. The relationship between the structure and physical properties is established. The frequency and temperature dependence of the dielectric properties reveal that this complex system has a high dielectric constant and low tangent loss. An analysis of impedance and related parameters illuminates the contributions of grains. The activation energy is determined for only the high temperature region in the temperature dependent AC conductivity graph. Deviation from the Debye behavior is seen in the Nyquist plot at different temperatures. The relaxation mechanism and the electrical transport properties in the sample are investigated with the help of various spectroscopic (i.e., dielectric, modulus, and impedance) techniques. This lead free sample will serve as a base for device engineering.

• 한국산업보건학회지
• /
• 제33권4호
• /
• pp.439-446
• /
• 2023

Objectives: The aims of this study are to investigate how X-rays are emitted to surrounding parts during the ion implantation process, to analyze these emissions in relation to the properties of the ion implanter equipment, and to estimate the resulting exposure dose. Eight ion implanters equipped with high-voltage electrical systems were selected for this study. Methods: We monitored X-ray emissions at three locations outside of the ion implanters: the accelerator equipped with a high-voltage energy generator, the impurity ion source, and the beam line. We used a Personal Portable Dose Rate and Survey Meter to monitor real-time X-ray levels. The SX-2R probe, an X-ray Features probe designed for use with the Radiagem^TM meter, was also utilized to monitor lower ranges of X-ray emissions. The counts per second (CPS) measured by the meter were estimated and then converted to a radiation dose (𝜇Sv/hr) based on a validated calibration graph between CPS and μGy/hr. Results: X-rays from seven ion implanters were consistently detected in high-voltage accelerator gaps, regardless of their proximity. X-rays specifically emanated from three ion implanters situated in the ion box gap and were also found in the beam lines of two ion implanters. The intensity of these X-rays did not show a clear pattern relative to the devices' age and electric properties, and notably, it decreased as the distance from the device increased. Conclusions: In conclusion, every gap, in which three components of the ion implanter devices were divided, was found to be insufficiently shielded against X-ray emissions, even though the exposure levels were not estimated to be higher than the threshold.

• 정보과학회 논문지
• /
• 제42권4호
• /
• pp.530-540
• /
• 2015

산업 무선 센서 네트워크는 뛰어난 성능과 신뢰성 있는 통신을 요구한다. 클러스터 구조는 네트워크를 형성하기 위해 소모되는 비용을 줄인다. 그리고 예약 기반 MAC 프로토콜은 네트워크 경쟁 기반 프로토콜에 비해 통신 성능 및 신뢰성이 더 뛰어나다. 이러한 구조를 갖춘 깊이 기반 TDMA 스케줄링 기법은 클러스터 네트워크상에서 깊이 정보에 따라 타임 슬롯을 분산적으로 각 센서 노드에 할당하는 방식이다. DB-TDMA가 깊이 기반 TDMA 스케줄링 기법 중 하나이고 확장성과 에너지 효율성을 보장한다. 하지만 분산 기법의 한계로 네트워크 전체 상황을 파악할 수 없어, 병렬 처리된 타임 슬롯 할당을 수행하기 어렵고, 충돌 문제를 완벽히 피할 수 없다. 이를 위해 본 논문은 DB-TDMA의 종단 간 지연시간을 감소시키기 위한 향상된 알고리즘을 제시한다. 그리고 제안 알고리즘을 DRAND와 DB-TDMA와 비교한다.

• 한국멀티미디어학회논문지
• /
• 제16권10호
• /
• pp.1147-1155
• /
• 2013

본 연구에서는 걸음 검출 알고리즘들의 걸음 검출률과 걸음 검출 결과를 상호 비교 분석할 수 있는 걸음검출 분석기를 구현하였다. 걸음 검출 분석기는 3축 가속도 센서의 데이터를 SVM 연산을 통하여 연속적인 에너지값으로 변환하고 걸음 측정 장치들에 사용되고 있는 걸음 검출 알고리즘들을 적용하여 걸음 검출결과를 동시에 비교할 수 있도록 함으로써 걸음 검출의 과정과 검출 형태, 그리고 정확성을 분석할 수 있게 하였다. 이를 위하여 걸음 검출 분석기는 에너지값을 에너지 파형 그래프로 나타내고, 걸음 검출 알고리즘을 에너지값에 적용하여, 걸음으로 검출된 Peak값들과 위치를 확인하고, 실제 걸음이 정상적으로 검출되지 않은 경우에는 원인을 시각적으로 분석할 수 있도록 하였다. 또한 걸음 검출 알고리즘마다 걸음 검출에 적용된 임계값을 그래프화하여 같이 표시함으로써, 걸음으로 인정되지 않는 경우에 사용된 임계값을 바로 확인하고, 이를 통하여 적절한 임계값을 구하는 수식의 조정에 필요한 요소들을 파악하는 데에 도움이 될 수 있도록 하였다. 본 연구에서 구현된 걸음 검출 분석기는 여러 걸음 검출 알고리즘을 수평적으로 비교, 분석함으로써 측정 장치에 가장 적합한 걸음 검출 알고리즘을 선택하거나, 기존의 걸음 검출 알고리즘의 성능 개선 방안을 파악하는 데에 효과적으로 활용할 수 있으므로 걸음 검출 알고리즘에 대한 연구, 또는 걸음 측정 장치의 설계에 폭넓게 활용될 수 있다.

• Korean Journal of Chemical Engineering
• /
• 제35권12호
• /
• pp.2327-2335
• /
• 2018

Fluid catalytic cracking (FCC) is an important chemical process that is widely used to produce valuable petrochemical products by cracking heavier components. However, many difficulties exist in modeling the FCC process due to its complexity. In this study, a dynamic process model of a FCC process is suggested and its structural observability is analyzed. In the process modeling, yield function for the kinetic model of the riser reactor was applied to explain the product distribution. Hydrodynamics, mass balance and energy balance equations of the riser reactor and the regenerator were used to complete the modeling. The process model was tested in steady-state simulation and dynamic simulation, which gives dynamic responses to the change of process variables. The result was compared with the measured data from operating plaint. In the structural analysis, the system was analyzed using the process model and the process design to identify the structural observability of the system. The reactor and regenerator unit in the system were divided into six nodes based on their functions and modeling relationship equations were built based on nodes and edges of the directed graph of the system. Output-set assignment algorithm was demonstrated on the occurrence matrix to find observable nodes and variables. Optimal locations for minimal addition of measurements could be found by completing the whole output-set assignment algorithm of the system. The result of this study can help predict the state more accurately and improve observability of a complex chemical process with minimal cost.

• International journal of advanced smart convergence
• /
• 제6권1호
• /
• pp.82-88
• /
• 2017

Emergency lights and exit signs are an indispensable part of safety precautions for effective evacuation in case of emergency in public buildings. These emergency sign indicates safe escape routes and emergency doors, using an internationally recognizable sign. However visibility of those signs drops drastically in case of emergency situations like fire smoke, etc. and loss of visibility causes serious problems for safety evacuation. This paper propose a novel emergency light and exit sign built-in with Bluetooth Low Energy (BLE) Beacon to assist the emergency self-guiding evacuation using devices for crisis and emergency management to avoid panic condition inside the buildings. In this approach, the emergency light and exit sign with the BLE beacons deployed in the indoor environments and the smart devices detect their indoor positions, direction to move, and next exit sign position from beacon messages and interact with map server in the Internet / Intranet over the available LTE and/or Wi-Fi network connectivity. The map server generate an optimal emergency exit path according to the nearest emergency exit based on a novel graph generation method for less route computation for each smart device. All emergency exit path data interfaces among three system components, the emergency exit signs, map server, and smart devices, have been defined for modular implementation of our emergency evacuation system. The proposed exit sign experimental system has been deployed and evaluated in real-time building environment thoroughly and gives a good evidence that the modular design of the proposed exit sign system and a novel approach to compute emergency exit path route based on the BLE beacon message, map server, and smart devices is competitive and viable.

• 한국정보통신학회논문지
• /
• 제26권3호
• /
• pp.469-478
• /
• 2022

본 논문은 산업용 생산 장비의 부하 전력을 모니터링하기 위한 스마트 디바이스와 애플리케이션을 개발하고 성능을 평가한 결과를 담고 있다. 스마트 디바이스는 산업용 생산 장비의 부하 전력 및 동작 환경 데이터를 수집해 이를 서버로 전송하는 기능을 가진 스마트 전력 디바이스와 이의 경량화 버전에 해당하는 에너지 미터링 디바이스로 구분해 하드웨어와 더불어 펌웨어를 개발하였다. 이들 디바이스에서 수집한 부하 전력 데이터는 AWS(Amazon Web Services) 서버내 MariaDB에 저장될 수 있도록 하였으며, RESTFul API를 이용해 웹사이트 및 모바일 애플리케이션 상에서 그래프 형태로 부하 전력을 모니터링할 수 있도록 구현하였다. 개발 시스템의 성능을 평가하기 위해 MariaDB에서 웹사이트 및 모바일 애플리케이션까지의 응답 시간을 측정하였으며, 4G(LTE) 네트워크 환경에서는 0.0256~0.0545초, 3G 네트워크 환경에서는 0.6126~1.2978초로 만족스러운 결과를 보여줌을 알 수 있었다.

• 대한영양사협회학술지
• /
• 제22권3호
• /
• pp.214-224
• /
• 2016

The purpose of this study was to assess the physical activity of preschool children using an accelerometer and investigate differences related to epoch length setting during use of the accelerometer. Subjects of the study were 26 children (12 boys and 14 girls) at the age of 5, enrolled in one preschool located in Gangneung. From 9:00 a.m. to 4:00 p.m. (7 hours period), every child wore a total of four accelerometers (ActiGraph $GT3X^+$, USA), including three attached to the left hip (with epoch length set at 5 seconds, 15 seconds, and 30 seconds). For comparison purposes, a forth was attached to the opposite position, with epoch length set at 5 seconds. Data collected using 15s epoch and 30s epoch (single larger epoch) were compared with those obtained after reintegration of 5s to 15s epoch, 5s to 30s epoch, and 15s to 30s epoch, respectively (smaller epochs reintegrated). According to the results of this study, there were no significant differences in VM between 30s epoch and 5s to 30s epoch reintegrated and in MVPA (moderate-to-vigorous physical activity), between 15s epoch and 5s to 15s epoch reintegrated. From the Bland-Altman plot, reintegration of 15s to 30s epoch in VM and reintegrations of 15s to 30s epoch and 5s to 15s epoch in MVPA can be recommended for assessing physical activity in preschool children. Further research is needed into the reintegration method while using an accelerometer for assessment of energy expenditure in children.

• The Journal of Korean Physical Therapy
• /
• 제12권3호
• /
• pp.319-329
• /
• 2000

The purpose of this study w8s to evaluate the effects of pulsed electromagnetic energy(Diapulse) and microcurrent on the wound healing in rabbits. 15 domestic rabbits were randomly assigned to the PRME(n=5). MC(n=5) and CON(n=91 group. Each rabbits were anesthetized with lidocaine HCL $2\%$. Skin wounds were created laterally on the back of IS domestic rabbits(33cm). From 24 hours after being injured, the rabbits of the PEME group were irradiated with an intensity of 3 at a 300 pulses per second, which were applied for 15 minutes every day during the 12 days. The MC group were stimulated with an intensity of $50{\mu}A$ at frequency of40 pulses per second, which were applied for 15 minutes every day during the 12 days. The CON group were not stimulated. The rabbits were sacrificed and the incised wound pans were processed appropriately for the light microscopic examination on the 3rd day, 6th day and 12th day before the beginning of wound treatment. The areas of wound were measured with metric graph paper. The results were as tallows. 1 The PRME and MC group compared with control group showed that wound closure rate increased on 6th, 12th day. 2. It was found that the CON group did not show a complete maturation and had a chronic inflammatory response. Judging from the irregularity of intercellular space and the loose alignment of connective tissue. these findings showed that wound healing was delayed. 3. It showed that inflammatory cells. fibroblasts and epithelial cells activity rapidly processed in the PEME group compared with the CON group. It was found that the PEMI; group showed a advanced remodeling of epithelial layer and a positive repair of connective tissue. 4. It showed that fibroblasts, epithelial cells and inflammatory cells activity rapidly processed in the MC group compared with the CON group. It was found that the MC group showed a improved remodeling of epithelial layer and a dense connective tissue.

• 대한전자공학회논문지SP
• /
• 제49권3호
• /
• pp.10-17
• /
• 2012

이미지 기반 3차원 장면은 비전 시스템, 게임, 가상현실 체험 등의 분야에서 쉽게 찾아볼 수 있다. 본 논문은 단일 영상으로부터 자동으로 3차원 가상 장면을 생성하기 위한 방법을 제안한다. 제안된 방법은 어린이용 도서의 팝업 이미지의 생성과 유사하다. 특히, 단일 외부 영상으로부터 장면의 3차원 기하학적 구조를 평가하기 위한 과분할 영상을 얻기 위해 텐서 보팅을 적용하였다. 텐서 보팅은 이미지의 균질 영역을 더욱더 부드러운 영역에 가깝게 만들며 영역 중심의 토큰은 매우 큰 saliency 값을 갖게 된다. 그리고 각 분할된 영역을 지면, 하늘, 수직성분 등의 대략적인 카테고리로 분류하고 라벨을 부여한다. 이 라벨은 간단한 가정 하에서 이미지를 팝업 모델로 변환시키기 위한 "잘라내기"와 "접기" 로 이용된다. 실험결과 제안된 방법은 복잡한 자연 영상에서도 성공적으로 영역 분할을 수행하였으며 분할된 영역 정보를 기반으로 구조 정보를 추론하여 3차원 팝업 영상으로 모델링하였다.