• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.91-96
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• 2012

The retract actuator makes the landing gear retract or extend during take-off and landing of an aircraft. To prevent folding of landing gear that has remained in the extended state because of an unexpected external disturbance, an internal locking device is applied to the retract actuator. The locking device is restrained with another internal component by oil pressure supplied to the retract actuator, and this restraint makes the locking of the actuator possible. Because locking and unlocking are repeated during retraction and extension of the landing gear, the locking device takes repeated identical loads, and the possibility of fatigue failure exists. In this study, the process and results of fatigue analysis for the locking device are presented, and the appropriateness of the analysis result is verified using a fatigue test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.6
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• pp.699-705
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• 2012

The role of a seat belt in a vehicle is to protect the driver from injury when a crash occurs. However when a large crash occurs, the driver slips forward and receives a strong impact. To prevent this situation, improvement of seat belts is essential. In this study, the new concept of a dynamic locking tongue (DLT) for seat belts is developed. The DLT device is used to reduce the impact to the driver's chest by tightening the webbing, so the driver is protected from severe injury in a large crash. First, a finite element model of the DLT device is created using SAMCEF and structural analysis is conducted with boundary conditions similar to those found in experiments. Then, the stress in the DLT device can be calculated. Second, the shape of the DLT device is optimized using the response surface analysis method in order to minimize the stress and weight. The validity of the optimization of the DLT device is verified using structural analysis.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.191-193
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• 2005

Flash memories are one of best media to support portable computer's storages. However, we need to improve traditional data management scheme due to the relatively slow characteristics of flash operation as compared to RAM memory. In order to achieve this goal, we devise a new scheme called Flash Two Phase Locking (F2PL) scheme for efficient data processing. F2PL improves transaction performance by allowing multi version reads and efficiently handling slow flash write/erase operation in lock management process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1353-1354
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• 2011

• Transactions of the Society of Information Storage Systems
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• v.2 no.4
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• pp.230-235
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• 2006

The machine locking system is an important device for the safety of persons using the machine. In this study, a locking system using electromagnetic fields is proposed to decrease the defects and the cost for repairing and maintenance of the existing locking system using structural mechanism. We analyze the electromagnetic locking system and calculate the generated force considering direction by the finite element method. Also, we set up two design domains for the topology optimization; first domain is optimized to reduce the volume and the other is optimized to maximize the generated force keeping the volume, especially. The optimal design is obtained by integration of the two optimized results. An improved design is obtained by the optimal topology and it is confirmed by comparison with the initial locking system.

• Proceedings of the Korean Magnestics Society Conference
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• 2011.06a
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• pp.73-74
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• 2011

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.9
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• pp.2362-2372
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• 1996

This paper deals with the design and development of an Injection-Locking Coupled Oscillators(ILCO), which functions like phase-shifter in the Active Intergrated Phased Array Antenna(AIPAA). This linear array 2-element ILCO consists of two Injection Locking Hair-pin Resonator Oscillators(ILHRO) and an unilateral amplifier. The first and second elements of the ILCO have same frequency tuning range but locking bandwidths of 11.5MHz and 14MHz respectively. A phase shift of .DELTA..PHI.=158.4.deg.(-78.0.deg. to 80.4.deg.) could be obtained inthe second element of ILCO when the first elementof the ILCO was in the reference locking mode(.DELTA..PHI.=0.deg.). When the ILCO is applied to the AIPAA, the predicted beam scanning angle value will be 38.4.deg.. Each ILCO gives good frequency stability and lower AM, FM, and PM noise charactheristics in the mutual coupling lockingmode. The ILCO can not only play a part as the phase shifter for the AIPAA but it can also be usedas the power combining device in the mm-wave frequency range and as a part of a T/R MMIC module.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.135-139
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• 2016

I propose a vector passive harmonic mode-locked fiber laser based on topological insulator Bi2Se3 interacting with a fiber taper with a diameter of 7 μm. The particles of topological insulator are deposited uniformly onto the fiber taper with light pressure effect. By incorporating the fabricated saturable absorber into an Er-doped fiber laser cavity, stable mode-locked fiber is obtained. Due to the intense evanescent field of the fiber taper, strong confinement of light enhances the nonlinearity of the laser cavity, and passive harmonic mode-locking is performed. I observe a maximum harmonic mode-locking of 356th, corresponding to a frequency of 3.57 GHz. The pulse duration is 824 fs, and the full width at half maximum of the spectrum is about 8.2 nm. The polarization dependent loss of the saturable absorber is ~ 2.5 dB in the wavelength range of the C band. As the cavity contains no other polarization dependent device, the mode-locked laser is functioning in the vector state. The harmonic order vs pump power is investigated. To the best of our knowledge, this report is the highest frequency mode-locked fiber laser based on Bi2Se3. Experimental results indicate that the topological insulator Bi2Se3 functioning with a thin fiber taper is effective for vector harmonic mode-locking.

• Journal of Drive and Control
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• v.21 no.1
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• pp.1-7
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• 2024

The locking performance of a multi-plate clutch with a mechanical lock-up system is governed by the engagement algorithm. In this paper, a control algorithm to improve the locking performance of the clutch was studied. A 1D dynamic model was constructed and simulated according to the developed algorithm. The developed algorithm was composed of a method in which the locking device is engaged while generating artificial slip on the friction plate by controlling the piston pressure of the clutch. Furthermore, a case study of the parameters within the developed algorithm was conducted to explore combinations that maximize locking performance and analyze trends according to these parameters.

• Journal of Internet Computing and Services
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• v.12 no.3
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• pp.17-26
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• 2011

We have developed a wearable device that can convert sensor data into real-time step counts. Sensor data on gait were acquired using a triaxial accelerometer. A test was performed according to a test protocol for different walking speeds, e.g., slow walking, walking, fast walking, slow running, running, and fast running. Each test was carried out for 36 min on a treadmill with the participant wearing an Actical device, and the device developed in this study. The signal vector magnitude (SVM) was used to process the X, Y, and Z values output by the triaxial accelerometer into one representative value. In addition, for accurate step-count detection, we used three algorithms: an heuristic algorithm (HA), the adaptive threshold algorithm (ATA), and the adaptive locking period algorithm (ALPA). The recognition rate of our algorithm was 97.34% better than that of the Actical device(91.74%) by 5.6%.