• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.597-603
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• 2014

The cargo of ships and offshore structures is the number of oil of combustibility and volatile, oil processing cargo. Furthermore heavy cargo of the vehicle or container box or bulk cargo are occupied the remainder of cargo. In addition, there is a possibility to move the location of the cargo and the vessel because it is received periodic / non-periodic a load of wave and ocean current. Therefore a shipboard hazard is much greater than onshore industry hazard. Monitoring and preparation for safety are necessary things because there is always risk of accidents arise from the impact of the freight and cargo of ships and offshore structures. In this study, we conducted a study with respect to the introduction of the wireless sensor network monitoring system to ensure the safety of the crew and workers on shipboard.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.513-519
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• 2016

In this study, dynamic vertical displacement of liquid in the tuned liquid column damper(TLCD) is measured by a laser Doppler vibrometer(LDV) to overcome limitations of existing sensors and to leverage noncontact sensing. Addressing advantages of noncontact measurements, operational principles of the LDV to measure velocity and displacement of a target object in motion is explained. The feasibility of application of the LDV to measurement of liquid motion in the TLCD is experimentally explored. A series of shake table tests with the TLCD are performed to determine requirements of application of the LDV. Based on the experimental results, it is proved that the LDV works under the condition of adding dye to the liquid by increasing the intensity of reflected laser and thus validity is verified by comparison with a conventional wave height meter.

• Journal of Ship and Ocean Technology
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• v.6 no.2
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• pp.23-36
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• 2002

This paper describes the powering, seakeeping and maneuvering performances for a 2,500-ton class trimaran. Influence of the side-hull forms and location of those in longitudinal and transverse direction to resistance performance was systematically investigated by a series of model tests and numerical calculations. It was found that the longitudinal location of side-hulls was the most influential design parameter to the resistance performance of the trimaran and the optimum location of side-hull depends on ship speeds. When the side-hull stem is located near the primary wave hollow generated by the main hull, the trimaran shows the best resistance performance. Powering performance of the trimaran is superior to those of similar mono-hull ships. Seakeeping model tests for the trimaran were executed and the results were compared with the theoretical results of a similar mono-hull ship. Generally speaking, seakeeping performance of the trimaran is superior to that of a mono-hull ship. In particular, pitching and rolling performance of the trimaran is excellent, which is due to the increased length and breadth. Maneuvering model tests using a HPMM equipment were executed to evaluate the maneuvering performance of the trimaran. Maneuvering simulation was performed using the maneuvering coefficients from the model tests. The results show that the control ability of heading angle and the direction keeping stability of the trimaran is excellent, even though the turning performance is rather worse compared to those of a similar mono-hull ship.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.24-30
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• 2016

An experimental study for the characteristics of the thrust-vectoring of a sonic jet utilizing the coanda flap installed at a rectangular nozzle exit is performed. Two side plates are installed at both sides of the flap to decrease the three dimensional effects of the jet on the flap surface. Schlieren flow visualizations and quantitative measurements of the deflection angle of thrusting vector show that the side plates are able to delay the separation of the jet at the downstream of the flap surface. Substantial increase in the deflection angle of the jet as high as $72^{\circ}$ and small thrust loss as low as 7% are obtained by the present thrust-vectoring technique using the side plates.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.12
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• pp.83-91
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• 1998

Fiber Bragg grating which has a blazed ang1e to the plane of incident wave generates a side-mode as well as main-mode. The side-mode has an identical characteristics with a long period grating that couples with a cladding mode, so rejects the special wavelength. We experimented on the side-mode characteristics with two fibers which Ge doped depressed index fiber and very high photosensitive H$_2$ loaded step index fiber according to the tilted angle. Also, using a phase mask equipped with rotation plate which has 0.02$^{\circ}$ resolution, we can control the bandwidth and the peak value of a total loss spectrum by aligned tilted grating in a fiber and using this, tried to compose the ASE band rejection filter of the Erbium doped fiber amplifier.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.68-76
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• 2010

Touch-enabled technology is increasingly being accepted as a main communication interface between human and computers. However, conventional touchscreen technologies, such as resistive overlay, capacitive overlay, and SAW(Surface Acoustic Wave), are not cost-effective for large screens. As an alternative to the conventional methods, we introduce a newly emerging method, an optical imaging touchscreen which is much simpler and more cost-effective. Despite its attractive benefits, optical imaging touchscreen has to overcome some problems, such as heavy computational complexity, intermittent ghost points, and over-sensitivity, to be commercially used. Therefore, we designed a hardware controller for signal processing and multi-coordinate computation, and proposed Infrared-blocked DA(Dark Area) manipulation as a solution. While the entire optical touch control took 34ms with a 32-bit microprocessor, the designed hardware controller can manage 2 valid coordinates at 200fps and also reduce energy consumption of infrared diodes from 1.8Wh to 0.0072Wh.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.107-113
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• 2014

A VCO (Voltage Controlled Oscillator) and a divide-by-4 high speed frequency divider are implemented using 65nm CMOS technology for 60GHz wireless communication system. The mm-wave VCO was designed by NMOS cross-coupled LC type using current source. The architecture of the divide-by-4 high speed frequency divider is differential ILFD (Injection Locking Frequency Divider) with varactor to control frequency range. The frequency divider also uses current sources to get good phase noise characteristics. The measured results show that the VCO has 64.36~67.68GHz tuning range and the frequency divider divides the VCO output by 4 exactly. The high output power of 5.47~5.97dBm from the frequency divider is measured. The phase noise of the VCO including the frequency divider are -77.17dBc/Hz at 1MHz and -110.83dBc/Hz at 10MHz offset frequency. The power consumption including VCO is 38.4mW with 1.2V supply voltage.

• Journal of IKEEE
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• v.21 no.3
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• pp.248-251
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• 2017

In this paper, The proposed board is developed by EMI compliant Dash Camera with $360^{\circ}$ omni angle. The proposed board is designed by designing DM and CM input noise reduction circuit and applying active EMI filter coupling circuit. The DM and CM input noise reduction circuit design uses a differential op amp circuit to obtain the DM noise coupled to the input signal via the parasitic capacitance(CP). In order to simplify the circuit by applying the active EMI filter coupling circuit, a noise separator is installed to compensate the noise of the EMI source to compensate the CM and DM active filter simultaneously. In order to evaluate the performance of the board for the proposed EMI response, an authorized accreditation body has confirmed that the electromagnetic certification standard for each frequency band is satisfied.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.18-25
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• 2001

The results of systematic numerical experiments of secondary gas injection thrust vector control are presented. The effects of secondary injection system such as injection location and nozzle divergent cone angle onto the overall performance parameters such as thrust ratio, specific impulse ratio and axial thrust augmentation, are investigated. Complex nozzle exhaust flows induced by the secondary jet penetration is numerically analyzed by solving unsteady three-dimensional Reynolds-averaged Navier-Stokes equations with Baldwin-Lomax turbulence model for closure. Numerical simulations compared with the experiments of secondary air injection into the rocket nozzle of $9.6^{\cire}$ divergent half angle showed good agreement. The results obtained in terms of overall performance parameters showed that locating the secondary injection orifice further downstream of primary nozzle ensures the prevention of occurrence of reflected shock wave, therefore is suitable for efficient and stable thrust vectoring over a wide range of use.

• Korean Journal of Optics and Photonics
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• v.17 no.2
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• pp.191-197
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• 2006

We analyze the self-pulsation(SP) characteristics due to mode beating of two modes emitted in a multi-section complex-coupled (CC) DFB laser composed of two DFB sections and a phase control section between them. SP frequency due to mode beating of the two modes is determined by the difference of grating periods in the two CC DFB regions. As the difference of grating periods in the two CC DFB regions increases, the SP frequency increases from very low frequency to the THz region. In the case of a mode which is not located in the stop band of the other DFB region, the mode propagates into the other DFB region without a high reflection, so that output powers emitted in a multi-section CC DFB laser have high modulation indexes due to the large interaction between the two modes.