• Journal of the Korean Chemical Society
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• v.17 no.4
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• pp.306-313
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• 1973

With the intention of obtaining technical data for the industrial production of ${\gamma}-MnO_2$ for dry cell depolarizer by electrolytic oxidation of acidic manganese sulfate solution made from domestic rhodochrosite, optimum conditions of ore leaching, purification of leached solution and electrolytic oxidation of divalent manganes to tetravalent were investigated using simulated micro pilot plant having a production capacity of 4 kg of $MnSO_4$ per day. The nature and quality of the products were investigated by means of chemical analysis, DTA, X-ray diffraction and electron microscopy. The cell activity of $MnO_2$were examined by cell discharging character measurements. The optimum electrolysis conditions were as follow: Temperature of the electrolyte, above $90^{\circ}C$; current density, 0.7${\sim}A/dm^2$; anode materials, graphite or lead ; concentration of electrolyte, $MnSO_4 50{\sim}150g/l $ g/l and $H_2SO_4/MnSO_4 = 0.15{\sim}0.25$. Under the best condition the current efficiency was 99% and the products were almost pure ${\gamma}-MnO_2$. The cell discharging character were good and almost the same as that of regular grade commercial electrolytic manganese dioxide.

• Therapeutic Science for Rehabilitation
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• v.8 no.4
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• pp.7-18
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• 2019

Objective : This systematic review aimed to investigate the impact of transcranial direct current stimulation combined with constraint-induced movement therapy (CIMT) in patients with stroke Methods : PubMed and NDSL databases were employed to review literature published between January 2009 and December 2018. The main search terms were "Transcranial direct current stimulation" or "tDCS," "Constraint-induced movement therapy" or "CIMT," "Upper extremity function," "Upper limb," and "Stroke." Based on the inclusion and exclusion criteria, 6 articles were selected. Furthermore, intervention effects on upper extremity function, activities of daily living, and cortical activity were assessed. Results : The current intensity, application time, and protocol of the CIMT varied the between studies. However, the intervention procedures to perform CIMT immediately after transcranial direct current stimulation was the same. Transcranial direct current stimulation combined with CIMT was effective in improving upper limb function and activities of daily living in patients with stoke and had a significant effect on cerebral cortex activation. Conclusions : This study provides information on transcranial direct current stimulation combined with CIMT for use by clinical therapists. Further studies are needed to standardize the stimulation time, current intensity, and electrode attachment position. Furthermore, randomized controlled trials, including long-term follow up, are needed for larger populations using the most appropriate CIMT protocol.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.1
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• pp.55-60
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• 2021

In order to produce wearable displays with high adhesion while maintaining flexible characteristics, the adhesive method using electro plating method was carried out. Laser lift-off (LLO) transcription was also used to remove sapphire substrates from LEDs bonded to fibers. Afterwards, the SEM and EDS data of the sample, which conducted the adhesion method using electro plating, confirmed that copper actually grows through the lattice of the fiber fabric to secure the light source and fiber. The adhesion characteristics of copper were checked using Universal testing machine (UTM). After plating adhesion, the characteristics of the LLO transcription process completed and the LED without the transcription process were compared using probe station. The electroluminescence (EL) according to the enhanced current was measured to check the characteristics of the light source after the process. As the current increases, the temperature rises and the bandgap decreases, so it was confirmed that the spectrum shifted. In addition, the change in the electrical characteristics of the samples according to the radius change is confirmed using probe station. The radius strain also had mechanical strength that copper could withstand bending stress, so the Vf variation was measured below 6%. Based on these results, it is expected that it will be applied to batteries, catalysts, and solar cells that require flexibility as well as wearable displays, contributing to the development of wearable devices.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.196-205
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• 2021

As industrial safety increases, various industrial accident prevention technologies using smart factory technology are being studied. However, small and medium enterprises (SMEs), which account for the majority of industrial accidents, are having difficulties in preventing industrial accidents by applying these smart factory technologies due to practical problems. In this study, customized monitoring and warning systems for each type of industrial accident were developed and applied to the actual field. Through this, we demonstrated industrial accident prevention technology through appropriate smart factory technology used by SMEs. A customized monitoring system using vision, current, temperature, and gas sensors was established for the four major disaster types: worker body access, short circuit and overcurrent, fire and burns due to high temperature, and emission of hazardous gas. In addition, a notification method suitable for each work environment was applied so that the monitored risk factors could be recognized quickly, and real-time data transmission and display enabled workers and managers to understand the disaster risk effectively. Through the application and demonstration of these appropriate smart factory technologies, the spread of these industrial safety technologies is to be discussed.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.4
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• pp.173-179
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• 2023

This paper analyzes the time-dependent dielectric breakdown(TDDB) degradation mechanism for each stress region of Peri devices manufactured by 4th generation VNAND process, and presents a complementary lifetime prediction model that improves speed and accuracy in a wider reliability evaluation region compared to the conventional model presented. SiON dielectric nMOSFETs were measured 10 times each under 5 constant voltage stress(CVS) conditions. The analysis of stress-induced leakage current(SILC) confirmed the significance of the field-based degradation mechanism in the low electric field region and the current-based degradation mechanism in the high field region. Time-to-failure(TF) was extracted from Weibull distribution to ascertain the lifetime prediction limitations of the conventional E-model and 1/E-model, and a parallel complementary model including both electric field and current based degradation mechanisms was proposed by extracting and combining the thermal bond breakage rate constant(k) of each model. Finally, when predicting the lifetime of the measured TDDB data, the proposed complementary model predicts lifetime faster and more accurately, even in the wider electric field region, compared to the conventional E-model and 1/E-model.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.65-76
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• 2024

With the recent activation of the offshore wind power industry, there has been a development of power plants with a scale exceeding 400MW, comparable to traditional thermal power plants. Renewable energy, characterized by intermittency depending on the energy source, is a prominent feature of modern renewable power generation facilities, which are structured based on controllable inverter technology. As the integration of renewable energy sources into the grid expands, the grid codes for power system connection are progressively becoming more defined, leading to active discussions and evaluations in this area. In this paper, we propose a method for selecting optimal reactive power compensation capacity when multiple offshore wind farms are integrated and connected through a shared interconnection facility to comply with grid codes. Based on the requirements of the grid code, we analyze the reactive power compensation and excessive stability of the 400MW wind power generation site under development in the southwest sea of Jeonbuk. This analysis involves constructing a generation site database using PSS/E (Power System Simulation for Engineering), incorporating turbine layouts and cable data. The study calculates reactive power due to charging current in internal and external network cables and determines the reactive power compensation capacity at the interconnection point. Additionally, static and dynamic stability assessments are conducted by integrating with the power system database.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1326-1331
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• 2006

Weld root gap is a important fact of a falling-off weld quality in various kind of weld defect. The welding quality can be controlled by monitoring important parameters, such as, the Arc voltage, welding current and welding speed during the welding process. Welding systems use either a vision sensor or an Arc sensor, both of which are unable to control these parameters directly. Therefore, it is difficult to obtain necessary bead geometry without automatically controlling the welding parameters through the sensors. In this paper we propose a novel approach using neural networks for detecting and monitoring of weld root gap and bead shape. Through experiments we demonstrate that the proposed system can be used for real welding processes. The results demonstrate that the system can efficiently estimate the weld bead shape and detect the welding defects.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.71.2-71.2
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• 2010

고체산화물연료전지는 청정에너지원으로써 기존의 발전방식을 대신할 차세대 에너지원으로 각광 받고 있다. 고체산화물 연료전지는 고온에서 작동하는 특성상 실험을 통하여 전극미세구조 및 구동조건을 최적화하는 것은 매우 어렵다. 본 연구는 전기화학식을 이용한 전산모사를 통해서 고체산화물 연료전지의 구동조건에 따른 성능 평가 및 전극의 미세구조 최적화 과정을 수행하였다. 전극 내 전달현상을 무시하고 오직 전기화학반응만을 고려한 전산모사는 단전지의 전극미세구조 및 구동조건에 따른 전지성능을 빠르게 예측할 수 있으며, 이를 기반으로 다양한 조건에서 얻은 전지 성능 데이터를 통해 전극미세구조를 최적화하였다. 개회로전압, 활성화분극, 저항분극, 물질수송손실을 표현하기 위하여 Nernst 식, Butler-Voler 식, 옴의 법칙, dusty-gas 모델을 각각 사용하였으며, 전극미세구조 및 구동조건의 변화는 물질확산계수 및 교환전류밀도를 통하여 그 영향이 전지성능에 반영된다. 온도, 압력, 주입 연료의 조성에 대한 성능평가가 수행되었으며, 1023K, 1 bar의 조건하에서 최적의 단전지 성능을 위한 기공도와 기공크기를 조사하였다. 더 향상된 단전지 성능 확보를 위해서 실험에서 쓰이는 기능층(functional layer)과 유사하게 넓은 반응 면적과 원활한 반응물 및 생성물의 이동을 보장하도록 기공도 및 기공크기를 그레이딩한 전극구조(graded-electrode)를 디자인하고 성능을 평가하였다. 그 결과 기존의 전지구조 대신에 그레이딩된 전극을 사용할 경우 50%이상 향상된 전지성능을 예측할 수 있었다.

• Journal of the Korean Electrochemical Society
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• v.13 no.4
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• pp.283-289
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• 2010

A two-dimensional isothermal model has been employed for numerical simulations of a high temperature hydrogen fuel cell with proton exchange membrane. The model is validated with existing experimental data and used for examination on the effects of various operating conditions on the fuel cell performance. The present numerical results show that the cell performance increases with increasing exchange current density, ion conductivity of the membrane, inlet gas flow rate as well as operating pressure. Also, higher porosity of gas diffusion layer (GDL) results in higher cell performance due to enhancement of the diffusion through the GDL, where the cathode GDL porosity more influences on the performance as compared with the anode one.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.5
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• pp.71-78
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• 2004

An infrared remote control-type transcutaneous control device using a $\mu$-processor is design for the totally implantable middle ear system. An infrared light transmission model for the tissue of skin was introduced and then a radiant intensity and the required current of the infrared light emitting diode(IR LED) driving circuit at transmission part were calculated for the external control device. And the transmission part generates IR signal by the system's own data protocol which prevents interferences from other infrared remote controls of the household appliances. The control part of the implanted device was designed to analyze functions of the received infrared(IR) signal that indicate the power ON/OFF and volume UP/DOWN. After the system is implemented, a data transmission experiments using 4 mm thickness of porcine skin were carried out. From the experiment, it was verified that the infrared control signal was transmitted to receiving module of the implemented system without any error.