• Journal of the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.281-289
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• 2019

In order to investigate the influence of thru holes near leading edge of model propeller on cavitation behavior, a model propeller with thru holes was manufactured and tested at Large Cavitation Tunnel (LCT). The pressure distribution around the thru hole on propeller blade was numerically calculated to help understand the local flow characteristics related to cavitation behavior. The model propeller is a five bladed propeller which has 2 blades with thru holes and 3 blades with smooth surface. The cavitation observation tests were conducted at angles of $0^{\circ}$ & $6^{\circ}$ using an inclined-shaft dynamometer in LCT. There are big difference on the suction side cavitation behavior each other due to the existence of thru hole. While the blades with thou holes start generation of the sheet cavitation from the leading edge on the suction side, the blades with smooth surface generate the cloud cavitation from the mid-chord. Cavitation on the blades with thru holes shows more similar behavior to those of the full-scale propeller of which the pipe line for air injection is closed. The numerical analysis result shows that the sharp pressure drop occurs around thru holes on the blade. Consequently, the thru hole around leading edge stimulates the cavitation occurrence and stabilizes the cavitation behavior. Based on these results, the effect of thru holes on propeller cavitation behavior behind a model ship should be studied in the future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.257-262
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• 2008

In this paper, the key parameters of $CO_2$ laser(focus depth, air blow rate, total laser beam time, number of pulse) are experimented for thru-hole and scribing line on AIN(aluminum nitride) substrate with high thermal conductivity. And, microstrip line & spiral planar inductor are fabricated on AIN substrate using 5 um Cu-plating with self-masking technique. The microstrip line of AIN has 0.1 dB/mm attenuation at 10 GHz and 6 nH spiral planar inductor has 56 maximum quality factor at 1 GHz. Thus, the AIN substrate is promising for GHz applications of high power area.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.826-831
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• 2009

In this paper, a high power RF amplifier module using AlN substrate of high thermal conductivity has been proposed. This RF amplifier module has the advantage of compact size and effective heat dissipation for the packaging of high power chip. To fabricate the thru-hole and scribing line on AlN substrate, the key parameters of $CO_2$ laser were experimented. And then, microstrip lines and spiral planar inductors were fabricated on an AlN substrate using the thin-film process. The fabricated microstrip lines on the AlN substrate has an attenuation value of 0.1 dB/mm up to 10 GHz. The fabricated spiral planar inductor has a high quality factor, a maximum of about 62 at 1 GHz for a 5.65 nH inductor. Packaging of a RF power amplifier was implemented on an AlN substrate with thru-hole. From the measured results, the gain is 24 dB from 13 to 15 GHz and the output power is 33.65 dBm(2.3 W).

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.934-937
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• 1999

MMIC 제작을 위한 단일 반도체 공정으로써 PECVD를 이용한 Si₃N₄의 증착, RIE를 이용한 CaAs via-hole건식식각, 그리고 airbridge 공정조건을 위한 실험 및 분석 작업을 수행하였다. Si₃N₄의 증착 실험에서는 굴절률이 2인 조건을, GaAs via-hole 식각 실험에서는 최적화된 thru-via의 모양과 식각률을 갖는 조건을, airbridge 실험에서는 polyimide coating 및 건식 식각 조건과 금 도금 및 습식 식각의 최적 조건들을 찾아내었다.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.8 no.1
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• pp.36-44
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• 1999

No one really doubts that the hottest area of dentistry in 21st century would most likely be 'implant'. With the support of a vast amount of research, implant has been successfully and rapidly absorbed into the field of general dentistry including private practitioners. For teeth with hopeless(or refractory) periodontitis or periapical pathosis, with no hesitation most dentists would think extraction as the sole treatment option followed by prosthodontic replacement possibly including implant. Not many dentists would take Trasplantation/Replantation as another treatment option for a particular condition. Dentistry is often more focused on 'Restoration' than 'Preservation' of natural dentition. 'Biologic Implant' is obviously much closer to the concept of 'Preservation'. Many different types of biologic implant system have been introduced to clinical dentistry so far. Many of those have failed to earn reasonable acknowledgement despite of the clinical success they brought. For some reason biologic implant has rather been alienated for long time. RPI(Ring Pin Implant) is designed to improve the prognosis and success rate of transplanted/replanted teeth. RPI is a Ti-based custom made implant system. It is fabricated either by electric casting or milling process. The major feature RPI gas is the 'ring & hole' structure. The hole should be no less than 1mm diameter to allow bone bridge formation thru it. The ring structure and bone bridge formation creates anti-torque activity, which largely increases the 'initial stability' of the transplanted/replanted teeth. It is also reported that RPI is beneficial in the aspect of resisting root resorption following replantation/transplantation procedure.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.4
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• pp.415-422
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• 2015

The flow field structures of dual jet-in-cross-flow were examined experimentally for in-lined perforated damage holes configuration using particle image velocimetry. Ensemble averaged in-plane velocity and vorticity data in the jet were determined to study the mean jet structure. Jets are formed by pressure differences between upper and lower airfoil surface. The flow structure of vicinity of the thru holes consist of a vortical structure that wrap around the jets like a horseshoe and develop further downstream through a pair of stream-wise vortices. The shape, size and location of the horseshoe vortex were found to be dependent on the angle of attack. In spite of the existence of battle damage holes, the effect on the control force was insignificant when the damage size was not large enough.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1136-1141
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• 2016

IoT technology has been used as a core technology of convergence service that needs intelligent information processing, and the importance is largely emerging now. And internal network construction thru IoT interaction device can connect with IoT device effectively, provide diverse services by connection with open platform. Especially, beacon that is based on low electric power bluetooth device is receiving attention as one of core technology of IoT. Beacon technology is utilized widly in various fields of industry, and there are lot of demands in the specific environment and conditions beyond the basic function. On this thesis, the authors are proposing the beacon device that utilized acceleration sensor and hole sensor. this beacon device can control the target on specific situation thru sensing of moving target. For the more, we will expect to apply to the various type of factory environments like detachable installation, optimized management using sensor.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.71-71
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• 2018

Sea pollution accidents have been occurred due to the increase of marine ship traffic. Oil spill from the hull hole induced by tanker collision results in the huge sea pollution. Proper and prompt reaction on such oil spill disaster is needed to minimize the damage. Thru-hull emergency wood plug is typically used to manually close small holes, while it is required to develop some mechanical devices for closing large holes in the hull due to huge fluid pressure. Accurate estimation of oil discharge and velocity from such holes are important to develop proper device to control hull hole damage. High resolution CFD modeling investigation on the configurations of hull hole of 7.5 m initial depth and 30 cm diameter, which was observed in the oil spill accident of the Hebei Sprit off the west coast of Korea in 2007, has been carried out to compute the oil spill velocity distribution in terms of flow depth. Friction loss due to the viscous flow and the discharge coefficient of crude oil with specific gravity SG = 0.85 and viscosity of $4-12cP(mPa{\cdot}s)$ at the temperature of $20^{\circ}C-100^{\circ}C$ are presented in terms of Reynolds number based on the results of high-resolution CFD modeling.

• Journal of the Korea Society of Computer and Information
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• v.14 no.4
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• pp.69-76
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• 2009

The construction of Internet IP-based Network is composed of router and switch models in a variety of companies. The construction by various models causes the complexity of the management and control as different types of CLI is used by different company to filter out abnormal traffics like worm, virus, and DDoS. To improve this situation, IETF is working on enacting XML based configuration standards from NETCONF working group, but currently few commands processing at the level of operation layer on NETCONF are only standardized and it's hard for unified control operation process between different make of system as different company has different XML command to filter out abnormal traffics. This thesis proposes ways to prevent abnormal attacks and increase efficiency of network by re-routing the abnormal traffics coming thru unified control for different make of systems into Sinkhole router and designing a control system to efficiently prevent various attacks after checking the possibility of including abnormal traffics from unified control operation.

• Journal of Korean Neurosurgical Society
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• v.65 no.6
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• pp.779-789
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• 2022

Objective : To analyze the effects of the number and shape of fenestrations on the mechanical strength of pedicle screws and the effects of bone cement augmentation (BCA) on the pull-out strength (POS) of screws used in conventional BCA. Methods : For the control group, a conventional screw was defined as C1, a screw with cannulated end-holes was defined as C2, a C2 screw with six pinholes was defined as C3, and the control group type was set. Among the experimental screws, T1 was designed using symmetrically placed thru-hole type fenestrations with an elliptical shape, while T2 was designed with half-moon (HM)-shaped asymmetrical fenestrations. T3 and T4 were designed with single HM-shaped fenestrations covering three pitches and five pitches, respectively. T5 and T6 were designed with 0.6-mm and 1-mm wider fenestrations than T3. BCA was performed by injecting 3 mL of commercial bone cement in the screw, and mechanical strength and POS tests were performed according to ASTM F1717 and ASTM F543 standards. Synthetic bone (model #1522-505) made of polyurethane foam was used as a model of osteoporotic bone, and radiographic examinations were performed using computed tomography and fluoroscopy. Results : In the fatigue test, at 75% ultimate load, fractures occurred 7781 and 9189 times; at 50%, they occurred 36122 and 82067 times; and at 25%, no fractures occurred. The mean ultimate load for each screw type was 219.1±52.39 N for T1, 234.74±15.9 N for T2, 220.70±59.23 N for T3, 216.45±32.4 N for T4, 181.55±54.78 N for T5, and 216.47±29.25 N for T6. In comparison with C1, T1, T2, T3, T4, and T6 showed significantly different ultimate load values (p<0.05). However, when the values for C2 and the fenestrated screws were evaluated with an unpaired t test, the ultimate load value of C2 significantly differed only from that of T2 (p=0.025). The ultimate load value of C3 differed significantly from those of T1 and T2 (C3 vs. T1 : p=0.048; C3 vs. T2 : p<0.001). Linear correlation analysis revealed a significant correlation between the fenestration area and the volume of bone cement (Pearson's correlation coefficient r=0.288, p=0.036). The bone cement volume and ultimate load significantly correlated with each other in linear correlation analysis (r=0.403, p=0.003). Conclusion : Fenestration yielded a superior ultimate load in comparison with standard BCA using a conventional screw. In T2 screws with asymmetrical two-way fenestrations showed the maximal increase in ultimate load. The fenestrated screws can be expected to show a stable position for the formation of the cement mass.