• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.2
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• pp.104-110
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• 2011

A CMOS Image Sensor (CIS) mounted on mobile appliances requires low power consumption due to limitations of the battery life cycle. In order to reduce the power consumption of CIS, we propose novel power reduction techniques such as a data flip-flop circuit with leakage current elimination and a low power single slope analog-to-digital (A/D) converter with a sleep-mode comparator. Based on 0.13 ${\mu}m$ CMOS process, the chip satisfies QVGA resolution (320 ${\times}$ 240 pixels) that the cell pitch is 2.25 um and the structure is a 4-Tr active pixel sensor. From the experimental results, the performance of the CIS has a 10-b resolution, the operating speed of the CIS is 16 frame/s, and the power dissipation is 25 mW at a 3.3 V(analog)/1.8 V(digital) power supply. When we compare the proposed CIS with conventional ones, the power consumption was reduced by approximately 22% in the sleep mode, and 20% in the active mode.

• Korean Journal of Optics and Photonics
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• v.18 no.6
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• pp.389-394
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• 2007

The characteristics of the single mode fiber hydrogen sensor have been investigated theoretically and experimentally. Palladium is adopted as a material for the transducer and a thin Ni film is used for the adhesion between the fiber end and the Pd film. It is shown that sensitivity and response time strongly depend on the thickness of Pd film. The single mode fiber sensor coated with 5 nm thick Ni adhesion layer and 10 nm thick Pd transducer layer showed 0.6 dB change of reflectivity and $3{\sim}5$ sec of response time as it absorbed 4% hydrogen gas.

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.311-317
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• 1999

Unidirectional single-mode operation of a diode-pumped Nd:YAG laser with a planar semimonolithic ring cavity has been demostrated at 1064 nm. The semimonolithic cavity consists of a laser active medium placed in a magnetic field, a crystal quartz plate, and an output coupling mirror. They form an optical diode by acting each part as a Faraday rotator, a reciprocal polarization rotator and a partial polarizer, respectively. An eigenpolarization theory for the cavity configuration was presented and losses for the eigenmodes were calculated. A pump-limited single-mode output power of 155 mW and a slope efficiency of 17% were obtained when the laser was pumped by a 1.2 W, 809 nm diode-laser. A laser linewidth of less than 100 kHz is inferred from a beat note frequency spectrum between two identical laser systems and continous single-mode tuning range was more than 2 GHz.

• Journal of the Korea Society of Computer and Information
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• v.26 no.6
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• pp.9-17
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• 2021

In this paper, we propose a reversely using the "Man In The Middle Attack" attack technique as a way to introduce network security without changing the physical structure and configuration of the existing network, a Virtual Network Overlay is formed with only a single Ethernet Interface. Implementing In-line mode to protect the network from external attacks, we propose an integrated control method through a micro network security sensor and cloud service. As a result of the experiment, it was possible to implement a logical In-line mode by forming a Virtual Network Overlay with only a single Ethernet Interface, and to implement Network IDS/IPS, Anti-Virus, Network Access Control, Firewall, etc.,. It was possible to perform integrated monitor and control in the service. The proposed system in this paper is helpful for small and medium-sized enterprises that expect high-performance network security at low cost, and can provide a network security environment with safety and reliability in the field of IoT and embedded systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.120-123
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• 2003

To investigate the characteristics of the single dendrimer molecule, we attempt to measure morphology and electrical properties of the self-assembled dendrimer on Au (111)substrate with SPM(scanning probe microscopy). The same self-assembly procedure was used for two different concentrations, $10{\mu}mol/ml$ and $100{\mu}mol/ml$. The case of lower concentration, we can measure the diameter and the height of the single molecule with the tapping mode AFM image. The imaged single molecules were dome shaped and the average diameter and height were 15.6 nm, 1.2 nm respectively. From these sizes, we can calculate the volume of the single molecule. The volume of the single molecule was estimated about $116nm^3$. However, that of higher concentration, it is difficult to obtain obvious image of the single molecule. To add to, I-V characteristics were investigated using STM, on which the phenomenon of negative differential resistance (NDR)was observed between 0.14 V and 0.24 V reproductively.

• Structural Engineering and Mechanics
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• v.53 no.4
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• pp.725-744
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• 2015

In this paper, a new damage indicator based on mode shape data is introduced to identify damage in beam structures. In order to construct the indicator proposed, the mode shape, mode shape slope and mode shape curvature of a beam before and after damage are utilized. Mode shape data of the beam are first obtained here using a finite element modeling and then the slope and curvature of mode shape are evaluated via the central finite difference method. In order to assess the robustness of the proposed indicator, two test examples including a simply supported beam and a two-span beam are considered. Numerical results demonstrate that using the proposed indicator, the location of single and multiple damage cases having different characteristics can be accurately determined. Moreover, the indicator shows a better performance when compared with a well-known indicator found in the literature.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.214-219
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• 2004

Crack tip behavior of single mode loading condition(mode I)depend on tensile loading component but one of mixed mode loading condition(mode I+II) have influenced on shear loading component like the practical structure. Because crack closure is caused by shear loading component under mixed-mode loading a research on the behavior in the stage of crack initiation and propagation require to be evaluate about crack closure effect by fatigue crack surface friction. For that reasion we examined the behavior at the crack tip by direct measuring method. Measured behavior at the crack tip was analyzed through vector crack tip displacement. As a result, crack propafation equation was corrected by considering with crack closure effect. In addition we compared fatigue fracture crack surface and crack closure level.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.1
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• pp.13-21
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• 2003

This paper presents the analysis of the mode characteristics of an annular ring microstrip patch antenna for circular polarization with attachment mode using method of moments in the spectral domain. For a probe excitation, the input impedance are obtained by using the single mode approximation for both the $TM_{11}$ and $TM_{12}$ modes and compared with those by Vector Hankel Transform. While the $TM_{11}$ mode has a high Q, it is a poor radiating mode; the $TM_{12}$ mode is more suitable for antenna applications. It is also shown that the bandwidth of the $TM_{12}$ mode is wider than that of the $TM_{11}$ mode in terms of axial ratio for circular polarizatio

• Smart Structures and Systems
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• v.9 no.6
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• pp.549-563
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• 2012

Theoretical analysis is performed on a multi-mode energy harvester design with focus on the first two vibration modes. Based on the analysis, a modification is proposed for designing a novel adaptive multi-mode energy harvester. The device comprises a simply supported beam with distributed mass and piezoelectric elements, and an adaptive damper that provides a 180 degree phase shift for the motions of two supports only at the second vibration mode. Theoretical analysis and numerical simulations show that the new design can efficiently scavenge energy at the first two vibration modes. The energy harvesting capability of the multi-mode energy harvester is also compared with that of a cantilever-based energy harvester for single-mode vibration. The results show that the energy harvesting capacity is affected by the damping ratios of different designs. For fixed damping ratio and design dimensions, the multi-mode design has higher energy harvesting capacity than the cantilever-based design.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.53.2-53.2
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• 2015

Fiber Bragg gratings (FBGs) are the most compact and reliable method of suppressing atmospheric emission lines in the infrared for ground-based telescopes. It has been proved that real FBGs based filters were able to eliminate 63 bright sky lines with minimal interline losses in 2011 (GNOSIS). Inscribing FBGs on multi-core fibers offers advantages. Compared to arrays of individual SMFs, the multi-core fiber Bragg grating (MCFBG) is greatly reduced in size, resistant to damage, simple to fabricate, and easy to taper into a photonics lantern (PRAXIS). Multi-mode fibers should be used and the number of modes has to be large enough to capture a sufficient amount of light from the telescope. However, the fiber Bragg gratings can only be inscribed in the single-mode fiber. A photonic lantern bi-directionally converts multi-mode to single-mode. The number of cores in MCFBGs corresponds to the mode. For a writing system consisting of a single ultra-violet (UV) laser and phase mask, the standard writing method is insufficient to produce uniform MCFBGs due to the spatial variations of the field at each core within the fiber. Most significant technical challenges are consequences of the side-on illumination of the fiber. Firstly, the fiber cladding acts as a cylindrical lens, narrowing the incident beam as it passes through the air-cladding interface. Consequently, cores receive reduced or zero illumination, while the focusing induces variations in the power at those that are exposed. The second effect is the shadowing of the furthest cores by the cores nearest to the light source. Due to a higher refractive index of cores than the cladding, diffraction occurs at each core-cladding interface as well as cores absorb the light. As a result, any core that is located directly behind another in the beam path is underexposed or exposed to a distorted interference pattern from what phase mask originally generates. Technologies are discussed to overcome the problems and recent experimental results are presented as well as simulation results.