• Journal of the Earthquake Engineering Society of Korea
• /
• v.28 no.3
• /
• pp.149-158
• /
• 2024

Piloti-type structures with vertical irregularity are vulnerable to earthquakes due to the soft structure of the first story. Structural characteristics of buildings can significantly affect the seismic loss function, calculated based on seismic fragility, and therefore need to be considered. This study investigated the effects of the number of stories and core locations on the seismic loss function of piloti-type buildings in Korea. Twelve analytical models were developed considering two variations: three stories (4-story, 5-story, and 6-story) and four core locations (center core, x-eccentric core, y-eccentric core, and xy-eccentric core). The interstory drift ratio and peak floor acceleration were assessed through incremental dynamic analysis using 44 earthquake records, and seismic fragility was derived. Seismic loss functions were calculated and compared using the derived seismic fragility and repair cost ratio of each component. The results indicate that the seismic loss function increases with more stories and when the core is eccentrically located in the piloti-type structure model. Therefore, the uncertainty due to the number of stories and core location should be considered when deriving the seismic loss function of piloti-type structures.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.929-932
• /
• 2005

We report a pull-up type RF MEMS switch using double electrode without elastic deformation of the cantilever involved in the actuation. At a voltage of 4.5 V, reliable actuations are achieved such that the movable lower contact pad is pulled up by the electrostatic force to make contact with the upper pad. At a frequency of 50 GHz, an insertion loss of 0.7 dB and an isolation of 50.7 dB are obtained from the switch. The measured transient times for switch-on and switch-off are 120 and 80 us, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.9-14
• /
• 2002

Ferrule is widely used as fiber optic connecters. In fiber-optic communications, the shape accuracy such as coaxiality and cylindricity of ferrule affects insertion loss. When coaxial grinding of ferrule supported by two pin, pin alignment and chucking accuracy are very important. In this research, the kinematic behavior of the ferrule center is investigated in the case where cone-shaped center pins and round circle hales which make contact with each other near the edge of the holes, using homeogenous coordinate transformation and numerical analysis. The obtained results are as follows: The alignment errors between center pins alone do not affect the rotation accuracy of ferrule. The alignment errors between center holes cause a sinusoidal displacement of ferrule. And the maximum displacement of ferrule centers increase in proportion to the center pin angle in the case of a fixed alignment errors

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.815-818
• /
• 2004

The emerging applications such as reliable back-up power system and renewable energy call for high boost U-n converter. The conventional topologies to get high output voltage are using flyback circuit, cascade converters, and coupled inductor DC-DC converter. They have the stress and loss related to the leakage energy which results in low efficiency Tn this paper, novel high boost converter is presented. It has a structure of cascade boost converter but only one switch. Therefore, drive circuit is simple and extreme duty ratio is eliminated. To verify the proposed circuit, theoretical analysis and experimental results has been done using a prototype power supply.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.987-991
• /
• 2003

Ferrule is widely used as fiber optic connecters. In fiber-optic communications, the shape accuracy such as coaxiality and cylindricity of ferrule affects insertion loss. When coaxial grinding of ferrule supported by two pin, pin alignment and chucking accuracy are very important. In this research, the kinematic behavior of the ferrule center is investigated in the case where cone-shaped center pins and round circle holes which make contact with each other near the edge of the holes, using homeogenous coordinate transformation and numerical analysis. The obtained results are as follows: The alignment errors between center holes cause a sinusoidal displacement of ferrule. And the maximum displacement of ferrule centers increase in proportion to the center pin angle. The relationship between center pins displacement in coaxial grinding and grinding accuracy was explained.

• 대한생식의학회:학술대회논문집
• /
• 1999.11a
• /
• pp.89-90
• /
• 1999

• Annals of dermatology
• /
• v.30 no.6
• /
• pp.704-707
• /
• 2018

Parry Romberg Syndrome (PRS), also known as idiopathic progressive hemifacial atrophy, is a rare neurocutaneous disorder characterized by loss of skin and subcutaneous fat of face, muscles, and bones causing unilateral atrophy. Most patients require only soft tissue augmentation although syndrome has varying grades of severity. In the majority of reported cases, it has been treated with surgical flap or autologous fat transplantation. However, these treatments need complicated surgical skills which take a lot of time and cost. Herein we report the first case of PRS augmented by hyaluronic acid (HA) filler in a 42-year-old female patient to suggest that HA filler could be a safe, simple, and even rational economic alternative to surgical treatment.

• Journal of Cerebrovascular and Endovascular Neurosurgery
• /
• v.26 no.3
• /
• pp.331-337
• /
• 2024

This is a unique case of metastatic pheochromocytoma of the cervical spine treated with preoperative embolization and subsequent en bloc resection. A 65-year-old man with metastatic pheochromocytoma presented with two weeks of worsening neck pain, left arm and leg weakness and paresthesia, and urinary incontinence. Magnetic resonance imaging showed a metastatic osseous lesion at C6 with severe stenosis and spinal cord compression. The patient underwent successful preoperative angiographic embolization with a liquid embolic agent followed by C5-C7 laminectomy, en bloc tumor resection, and C3-T2 posterior spinal fusion. Six weeks postoperatively, the patient reported improving strength and resolving neck pain and paresthesias. While there is no standard paradigm for the treatment of metastatic pheochromocytomas of the cervical spine, preoperative embolization may minimize intraoperative blood loss and hemodynamic instability during subsequent surgical resection.

• Journal of the Microelectronics and Packaging Society
• /
• v.14 no.2 s.43
• /
• pp.41-47
• /
• 2007

Today lots of investigations on Embedded Passive Technology using materials and chip components have been carried out. We fabricated diplexers with 1005 sized-passives, which were made by burying chips in PCB substrate and surface mounting chip on PCB. 6 passive chips (inductors and capacitors) were used for the frequency divisions of $880\;MHz{\sim}960\;MHz(GSM)$ and $1.71\;GHz{\sim}1.88\;GHz(DCS)$. Two types of diplxer were characterized with Network analyzer. The chip buried diplexer showed extra 5db loss and a little deviation of 0.6GHz at aimed frequency areas, whereas the chip mounted diplexer showed man. 0.86dB loss within GSM field and max. 0.68dB within DCS field respectively. But few degradations were observed after $260^{\circ}C$ for 80min baking and $280^{\circ}C$ for 10sec solder floating.

• Journal of the Korean Electrochemical Society
• /
• v.12 no.2
• /
• pp.148-154
• /
• 2009

With respect to the durability of large scale ($150cm^2$) membrane electrode assembly (MEA) of direct methanol fuel cell (DMFC), degradation phenomena at cathode is monitored and analyzed according to the position on the cathode surface. After constant current mode operation of large scale MEA for 500 hr, the MEA is divided into three parts along the cathode channel; (close to) inlet, middle, and (close to) outlet. The performance of each MEA is tested and it is revealed that the MEA from the cathode outlet of large MEA shows the worst performance. This is due to the catalyst degradation and GDL delamination caused by flooding at cathode outlet of large MEA during the 500 hr operation. Particularly on the catalyst degradation, the loss of electrochemically active surface area (ECSA) of catalyst gets worse along the cathode channel from inlet to outlet, of which the reason is believed to be loss of catalysts by dissolution and migration rather than their agglomeration. The extent of loss in the performance and catalyst degradation has strong relation to the cathode flooding and it is required to develop proper water management techniques and separator channel design to control the flooding.