• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.294-298
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• 2000

The output characteristics of intracavity frequency doubling of laser-diode end-pumped Nd:S-VAP laser were investigated. Nd:S-VAP is suitable for a microchip laser medium, which has a low threshold property because of a very high value of the stimulated emission cross-section and lifetime product. The threshold energy measured was 81 J.ll. The second harmonic output energy measured was $126\mu\textrm{J}$at a pump energy of $2\mu\textrm{J}$. We described for intracavity frequency doubling by using theoretical calculations. Q-switched second harmonic energy measured was $15\mu\textrm{J}$per pulse with a pulse-width of 26 ns. at a pump energy of 2 mJ and an $M^2$ of 1.47 represented a good beam quality. ality.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.117-121
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• 2018

A Wireless Sensor Network is a network that is composed of wireless sensor nodes. There is no restriction on the place where it can be installed because it is composed wirelessly. Instead, sensor nodes have limited energy, such as batteries. Therefore, to use the network for a long time, energy consumption should be minimized. Several protocols have been proposed to minimize energy consumption, and the typical protocol is the LEACH protocol. The LEACH protocol is a cluster-based protocol that minimizes energy consumption by dividing the sensor field into clusters. Depending on how you organize the clusters of sensor field, network lifetimes may increase or decrease. In this paper, we will improve the network lifetime by improving the cluster head selection method in LEACH Protocol.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.5
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• pp.526-531
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• 2001

The flow of remote field eddy current energy is studied at nonmagnetic coaxial tubes by using both experiments and finite element calculations based on commercial software package. The results showed that remote field eddy current energy at coaxial tubes flow along over the outer surface of external tube, not through the gap between internal and external tubes. This means that the through wall transmission characteristic of remote field eddy current testing (RFECT) is still valid at tube in tube configurations and the RFECT could be potential nondestructive technique for crack detection, spacer location and gap sizing at the coaxial CANDU fuel channel tubes.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.3
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• pp.80-85
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• 2008

Capsule endoscopes generally use primary cells as a power source due to its limited space. However, the primary cells have several limitations such as high cost, limited power and no reuse. To solve these problems, a new wireless energy transmission method is proposed. The proposed approach uses air-gap transformer concepts and LC resonance to transmit energy from transmitter(primary side) to capsule endoscopes(secondary side). The ferrite core with 3-axis winding is used to increase energy transfer efficiency regardless of direction and location. The experimental results show that the proposed method stably supplies 30mW power to secondary circuit.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.10-16
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• 2010

As the study of ubiquitous computing environment has been very active in recent years, the senor network technology is considered to be a core technology of it. This wireless sensor network is enabled to sense and gather data of interest from its surroundings by sensor nodes applied in physical space. Each sensor node structuring the sensor network is demanded to execute the required service using limited resources. This limited usage of resources requires the sensor node to energy-efficiently perform in building wireless sensor network, which enables to extend the entire network life. This study structures a system able to monitor changing environment data on a real-time basis using a computer remotely as it energy-efficiently gathers and sends environment data of specific areas.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.226.1-226.1
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• 2014

이온빔 소스는 반도체 및 디스플레이 공정에 있어, 표면 에칭 및 증착 등 여러 응용 분야에 활발히 이용되고 있다. 본 연구에 사용된 원형 이온빔 소스는 선형 이온빔 소스의 가장자리에서의 특성 분석을 위해 제작되었으며, 높은 직류전압과 자기장 공간에서 플라즈마를 방전시키고 발생된 이온들을 가속시켜 높은 에너지의 이온빔을 발생시킨다. 이온빔 특성 분석을 위해 전위지연 탐침과 패러데이 탐침을 개발하였다. 전위지연 탐침은 격자판에 전압을 인가하여 선택적으로 이온을 수집하고, 이온의 에너지분포함수를 측정한다. 패러데이 탐침은 이온 수집기와 가드링으로 구성되어 수집기 표면에 일정한 플라즈마 쉬스를 형성하여 정확한 이온전류밀도를 측정한다. 본 연구에서는, 아르곤 기체를 이용하여 기체유량(8~12 sccm) 및 방전전압(1~2 kV)에 따라 방전전류 16~54 mA, 소모전력 16~108 mW의 특성을 보였다. 운전압력은 0.4~0.54 mTorr이며, 이온소스로부터 18 cm 거리에서 이온전류밀도와 이온에너지분포를 측정하였다. 또한, 중공음극선을 이용하여 인위적으로 전자를 이온 소스에서 발생된 플라즈마에 공급하고 이온빔 및 플라즈마의 특성 변화를 위 시스템에서 분석하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.177-177
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• 2012

진공을 기초로 한 다양한 반도체 식각 공정에서 RF bias가 결합된 유도 결합 플라즈마 소스는 널리 사용되고 있다. 하지만, 대부분의 연구는 RF bias에 의한 자기 바이어스 효과에만 한정되어 있으며, 공정 결과와 소자 품질에 결정적인 역할을 하는 플라즈마 변수들(전자 온도, 플라즈마 밀도)과 RF bias의 상관관계에 대한 연구는 거의 없는 실정이다. 본 연구에서는 RF bias가 플라즈마 변수에 미치는 영향과 비충돌 전자 가열 메커니즘의 실험적 증거에 관한 연구를 진행하였다. 플라즈마 밀도는 RF bias에 의하여 감소 또는 증가하였으며, 이러한 결과는 Fluid global model에 의한 계산과 잘 일치하는 결과를 보였다. 전자 온도는 RF bias에 의하여 증가하였으며, 적은 RF bias 전력에서는 플라즈마 전위에 갇혀있는 낮은 에너지 그룹의 전자들의 가열이 주가 되었으나, 큰 RF bias 전력에서는 높은 에너지 그룹의 전자들의 가열이 주가 됨을 관찰하였다. 이는 높은 에너지 그룹의 전자 가열 메커니즘이 anomalous skin effect에서 collisionless sheath heating으로 전이되는 것을 나타내며, bounce resonance heating이 RF bias의 전자가열에 중요한 역할을 함을 보여주는 실험적 근거이다. 플라즈마 밀도의 공간 분포는 RF bias의 인가에 의하여 더욱 균일함을 보였으며, 이는 (electro-static and electro-magnetic) edge effect에 의한 영향으로 해석될 수 있다. 이러한 RF bias와 플라즈마 변수들의 상관관계 및 전자 가열 메커니즘에 대한 연구는 방전 특성의 물리적 이해뿐만 아니라, 반도체 식각 공정에서 소자 품질 및 공정 개선을 위한 최적의 방전 조건 도출과 외부 변수 제어에 큰 도움을 주리라 예상된다.

• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.607-614
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• 2015

This study evaluated the flexural performance of steel and PP fiber reinfroced shotcrete using round panel test according to ASTM that can consider the actual stress of fiber reinforced shotcrete in tunnel and under ground structures. The results of round panel test are converted to the square panel test results according to the EFNARC. The energy absorptions of each fiber reinforced shotcrete were classified according to the EFNARC toughness classification. Test results show that the PP fiber reinforced shotcrete has better flexural performance compared with the steel fiber reinforced shotcrete.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.221-227
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• 2013

In this paper, zero-energy house in order to monitor the energy savings come with Zigbee communication temperature humidity, smoke detection, illumination and CO2 to develop complex sensor board a protocol for handling about it dealt. In particular, indoor space to mount the sensor based on the location of the control algorithm, so it varies through the Zigbee wireless sensor mounting position is free, and the advantage of being able to change. Also, the energy loss that occurs through the window can be reduced to the room lighting can play an important role in the control system.

• The Journal of the Korea Contents Association
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• v.12 no.11
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• pp.458-468
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• 2012

The purpose of this study is to define U-Eco City services and to analyze the possibility and easiness of application in urban space. The most significant meaning of this study is that these results could be used as the design and planning guidelines for integrated U-Eco City. This study progress as follows; First, U-Eco City concept and their services were defined and the spatial units of U-Eco City were distinguished through literature review. Second, U-Eco City spaces are classified into four levels such as building, street, facility and district. Finally, the application of U-Eco city services was analyzed together by the statistical technique of cross-tabulation. 35.7% of U-city services was serviced in urban district and 38.8% of Eco City services was applied to Building. U-City and/or Eco city services were adapted differently according to the urban spatial hierarchy. Those services should be applied in terms of the characteristics of urban space in designing and planning U-Eco City.