• Journal of Power Electronics
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• v.4 no.1
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• pp.46-55
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• 2004

This paper presents a high-frequency ZVS-PWM boost chopper-fed DC-DC converter with a single active auxiliary edge resonant snubber in the load-side which can be designed for power conditioners such as solar photovoltaic generation, fuel cell generation, battery and super capacitor energy storages. Its principle operation in steady-state is described in addition to a prototype setup. The experimental results of ZVS-PWM boost chopper-fed DC-DC converter proposed here, are evaluated and verified with a practical design model in terms of its switching voltage and current waveforms, the switching v-i trajectory, the temperature performance of IGBT module, the actual power conversion efficiency and the EMI of radiated and conducted emissions. And then discussed and compared with the hard switching scheme from an experimental point of view. Finally, this paper proposes a practical method to suppress parasitic oscillation due to the active auxiliary resonant switch at ZCS turn off mode transition with the aid of an additional lossless clamping diode loop, and reduced the EMI conducted emission in this paper.

• 한국해양학회지
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• v.16 no.1
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• pp.12-23
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• 1981

A numerical experiment is made in order to clarify the mechanism of the upwelling phenomenon along the coast near the poleward edge of the western boundary current. The possibility of the upwelling is suggested from the analysis of the observational data in the east of Honshu, Japan, and in the south eastern coast of Korean Peninsula. This upwelling phenomenon is very deep and can be traced to the bottom layer. The upwelling phenomenon seems to be a general oceanic feature which characterizes the region along the west coast near the poleward edge of the western boundary current. This experiment is simulating the oceanic condition of the transition region between Kuroshio front and the Oyashio front in the east of Honshu, Japan. The possible explanations of the causes of the upwelling are as follows;In the interior of the modeled ocean the cold heavy water supplied from the north and the warm light water from the south make the north-south gradient of the pressure field and accelerate the eastward current to produce the h-orizontal divergence feld near the west coast. The divergence is compensated by the upwelling near the separation region. Another one is that the upwell-ed cold water strengthen constantly the pressure gradient which is balanced by the northward current and is weakened by the horizontal diffusion.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.559-575
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• 2023

3D human pose estimation is widely applied in various fields, including action recognition, sports analysis, and human-computer interaction. 3D human pose estimation has achieved significant progress with the introduction of convolutional neural network (CNN). Recently, several researches have proposed the use of multiview approaches to avoid occlusions in single-view approaches. However, as the number of cameras increases, a 3D pose estimation system relying on a CNN may lack in computational resources. In addition, when a single host system uses multiple cameras, the data transition speed becomes inadequate owing to bandwidth limitations. To address this problem, we propose a distributed real-time 3D pose estimation framework based on asynchronous multiple cameras. The proposed framework comprises a central server and multiple edge devices. Each multiple-edge device estimates a 2D human pose from its view and sendsit to the central server. Subsequently, the central server synchronizes the received 2D human pose data based on the timestamps. Finally, the central server reconstructs a 3D human pose using geometrical triangulation. We demonstrate that the proposed framework increases the percentage of detected joints and successfully estimates 3D human poses in real-time.

• Steel and Composite Structures
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• v.18 no.1
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• pp.135-148
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• 2015

The cutout hole locating at the place of rib-to-diaphragm welded connection is adopted to minimize the restraint, which is caused by the floor-beam web to rib rotation at the support due to the unsymmetrical loads in orthotropic deck. In practice, an inevitable problem is that there is a large number of welding joint's cracks formed at the edge of cutout hole. In this study, a comparative experiment is carried out with two types of cutout hole, the circular arc transition and the vertical transition. The fatigue life estimation of specimens is investigated with the application of the structural hot spot stress approach by finite element analyses. The results are compared with the ones of the fatigue tests which are carried out on these full-scale specimens. Factors affecting the stress range are also studied.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.7
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• pp.75-81
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• 1993

In this paper, New type of Static Edge Triggered D Flip-Flop Circuits which are effective for the sequencial selecting and addressing of Matrix type Electrodes being applied to Flat Display Devices is proposed by the Design Technique using the Transmission Characteristics of Feedback Transistors and Charge Back Up Function. These Circuits composed of 2-4 less transistors in number than Conventional Static D Flip Flop's have some advantages that the Maximum Transition Time of Clock Signals allowed is increased by 100-450 times more than that of the Conventional circuit at 100KHz Clock Frequence and Circuit Safety is much increased by making the wider ranges, 1-4V, of Clock Levelas a Non-operating periods than 3-3.2V ranges in case of the Conventional Circuit at 10MHz clock frequence. By these advantages, These circuits can be very effectively used in case that clock signal has long transition time, especially on the low frequency operation.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.201-201
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• 2006

In this study the glass transition temperature in thin polymer films has been studied. Ellipsometry has been used to measure $T_{g}$ of thin film as a function of film thickness. Empirical equation has been proposed to fit the measured $T_{g}$ pattern with thickness. Also, a continuous multilayer model was proposed and derived to describe the effect of surface on the observed $T_{g}$ reduction in thin films, and the depth-dependent $T_{g}$ profile was obtained. These results showed that $T_{g}$ at the top surface was much lower than the bulk $T_{g}$ and gradually approached the bulk $T_{g}$ with increasing distance from the edge of the film. The model and equation were modified to apply for the polymer coated on the strongly favorable substrate and the freely standing film.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.257-259
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• 2002

As a new host material for a red phosphor for PDP applications, has studied (Y,Gd)$Al_3(BO_3)_4$ which gives non-centrosymmetric sites for $Eu^{3+}$ activators. Vacuum ultraviolet (VUV) excitation spectrum of new red phosphor (Y,Gd)$Al_3(BO_3)_4$:$Eu^{3+}$ has two broad bands. One band with the absorption edge at ca. 168 nm is the band-gap absorption of aluminoborate and the other broad band centered 240 nm is the charge transfer transition between $Eu^{3+}$ and the neighboring oxygen anions. The PL spectrum shows the strongest emission at 617 nm due to the electric dipole $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$, whose luminescent chromaticity is (0.67, 0.33).

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.43-47
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• 1997

A procedure presented in this paper generates test sequences to check the conformity of an implementation with a protocol specification, which is modeled as a deterministic finite state machine (FSM). Given a FSM, a common procedure of test sequence generation, first, constructs a directed graph which edges include the state check after each transition, and produces a symmetric graph G* from and, finally, finds a Euler tour of G*. We propose a technique to determine a minimum-cost tour of the transition graph of the FSM. The proposed technique using Multiple Unique State Signature (MUSS) solves an open issue that one MUIO sequence assignment may lead to two more edges of unit cost being replicated to from G* while an optimal assignment may lead to the replication of a single edge of high cost. In this paper, randomly generated FSMs have been studied as test cases. The result shows that the proposed technique saves the cost 4∼28% and 2∼21% over the previous approach using MUIO and MUSP, respectively.

• Wind and Structures
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• v.28 no.3
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• pp.191-201
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• 2019

In this paper, the aerodynamic analysis of a vertical axis wind turbine was carried out by CFD approach to optimize the turbine performance. To perform numerical simulation, SST-Transition turbulence model was used, which demonstrated more precise results compared to non-transition models. A parametric study was conducted to optimize the VAWT performance based on the selected model. The investigation of pitch angle changes showed that the highest power produced by the turbine occurs at $2^{\circ}$ angle. Considering the effect of the rotor's arm junction to the airfoil showed that by increasing the distance of the junction from the edge of the airfoil from 25 cm to 40 cm, the power of the turbine increases by 60%. However, further increase in this distance results in power decrease. Based on the proposed numerical model, a case study was conducted to consider the installation of four VAWTs in the southwest corner of the medical science building at TMU campus with a height of 42m. The results of the simulation showed that 8.27 MWh energy is obtainable annually.

• Journal of the Korean Chemical Society
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• v.48 no.1
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• pp.46-52
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• 2004

The effect of crystallinity on the structural stability of layered manganese oxide has been systematically investigated. While well-crystalline manganate was prepared by solid-state reaction-ion exchange method, nanocrystalline one was obtained by Chimie-Douce reaction at room temperature. According to micro-Raman and Mn K-edge X-ray absorption spectroscopic results, manganese ions in both the manganese oxides are stabilized in the octahedral sites of the layered lattice consisting of edge-shared MnO6 octahedra. The differential potential plot clarifies that the layered structure of nanocrystalline material is well maintained during electrochemical cycling, in contrast to the well-crystalline homologue. From the micro-Raman results, it was found that delithiation-relithiation process for well-crystalline material gives rise to the structural transition from layered to spinel-type structure. On the basis of the present experimental findings, it can be concluded that nanocrystalline nature plays an important role in enhancing the structural stability of layered manganese oxides.