• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.911-915
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• 2014

Pyrotechnic devices are widely used for space appendages. However, a cube satellite requirements do not permit the use of explosive pyrotechnic device. A nichrome burn wire release has typically been used for holding and release of deployable appendages of the cube satellite due to its simplicity and low cost. However, relatively low mechanical constraint force and system complexity for application of multi-deployable systems are disadvantages of the conventional mechanism. To overcome these drawbacks, we have developed a segmented nut type holding and release mechanism based on the nichrome burn wire release. The great advantages of the mechanism are much lower shock level and larger constraint force than the conventional mechanism using pyro. Flight model for on-orbit verification was developed and verified through release function test, vibration test and thermal vacuum test.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.229-237
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• 2011

The pullout test is a nondestructive testing method certified by the American Society for Testing and Materials (ASTM) and British Standards (BS). Research has shown that it is very reliable in terms of evaluating the concrete strength of reinforced concrete members. However, the pullout test is rarely performed on domestic construction sites due to the complex procedures and high costs involved. This study proposes a new pullout test composed of a post installable break-off bolt, an insert nut, and a pullout tester, which satisfy both economical and practical purposes on a construction site. Three different types of special fastening methods, a temporary fixed bolt, a plastic fixed panel, and a fixed bar, have been developed. A pullout tester is proposed that is driven by the circle force introduced into a handle composed of eight gears without a load cell and a hydraulic cylinder. The serviceability and reliability of these instruments were investigated through experiments at construction sites. Furthermore, the sample pullout test with a wall specimen was conducted to estimate the usefulness of the temporary fixed bolt type of fastening methods and pullout devices. Eventually, the developed instruments will be useful on construction sites if minor requirements are met.

• Journal of Korean Society of Steel Construction
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• v.20 no.3
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• pp.399-407
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• 2008

The clamping of torque shear bolt is based on KS B 2819. It was misunderstood that the tension force of the TS bolt was induced generally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the intended tension, as it considerably varies due to torque coefficient dependent on temperature variables despite the break of the pin tail. In this study, the tension of torque shear bolts were compared with two types of high-strength hexagon bolts by temperature parameters from ${-10^{\circ}C}$ to ${50^{\circ}C}$. Torque shear bolts showed that the average clamping force increased to 20kN as the temperature increased. In case of galvanized high-strength hexagon bolts, the average clamping forces at $0^{\circ}C$, $20^{\circ}C$, $50^{\circ}C$ were recorded over standard bolt tension, 178kN, and the worst standard deviation was 50kN. In case of high-strength hexagon bolts, ave rage clamping forces increased as the temperature went up, and the worst standard deviation was 33kN lower than that of galvanized high-strength hexagon bolts. As for the turn-of-the-nut method, at nut rotation of ${90^{\circ}}$, two types of high-strength hexagon bolts did not met the intended design bolt in tension, 162kN.it is neccessary to re-evaluate the range of turn of nut, ${120^{\circ}{\pm}30^{\circ}}$.

• 한국정보통신설비학회:학술대회논문집
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• 2004.08a
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• pp.86-89
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• 2004

현재 센서 너트워크와 홈네트워크 분야에 대한 연구가 활발히 진행 중이다. 아직까지 센서 네트워크 분야는 기존의 네트워크 시스템에 연결된 형태의 연구가 많았고 홈 네트워크는 가전기기를 중심의 연구가 대부분이었다. 이런 문제를 해결하기 위해 센서네트워크를 관리할 수 있는 OSGi 기반의 서비스 미들웨어를 설계하였다. 서비스 미들웨어는 OSGi 프레임워크상에서 동작하며 센서 네트워크 시스템과 연동하기 위한 번들과 OSGi 프레임워크 사의 번들을 제어하는 관리 번들로 구성하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.573-574
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• 2009

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.472-474
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• 2000

본 논문은 VOD 시스템에서 QoS를 보장해 주기 위한 흐름 제어 기법을 제안하고 실제 구현된 VOD 시스템에서 제안된 알고리즘을 적용하고 성능을 측정하였다. 기존의 버퍼를 관리하는 Leaky Bucket 알고리즘과 패킷의 손실률에 기반한 네트워크의 상태를 동시에 고려해서 클라이언트와 서버간에 전송 속도를 제어한다. 즉, 시간에 따라 변화하는 네트워크의 상태를 클라이너트 버퍼 관리에 반영해줌으로써 클라이언트 버퍼의 오버플로우 및 언더 플로우를 방지하고 QoS를 보장한다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.173-175
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• 1998

정보 전달의 매개체로 사용되는 WWW와 많은 사업에 필수적으로 필요한 지리정보시스템의 결합은 많은 장점을 가진다. 본 논문에서는 WWW상에서 동작하는 지리정보 시스템인 WGIS를 설계한다. WGIS의 설계에 있어서 공간 객체 저장시스템인 GeoStore를 GIS로 사용하고, 이식성이 높은 Java로 클라이너트를 확장하고, NSAPI를 사용하여 서버를 확장한다. 상호 대화식으로 동작하도록 사용자 인터페이스를 설계하고, 다양한 질의 처리가 가능하도록 클라이언트/서버의 동작을 정의하고, 서버의 응답시간이 늦어지지 않도록 지리정보를 손실 없이 압축 전송할 수 있는 포맷을 정의한다.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.34-37
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• 2011

This paper presents sealing contact stress and deformation behaviors of an elastomeric contact seal for a pipe connection. In this study, a pipe connection is used by a joint nut and an elastomeric contact seal with a sealing interference of 0.2~0.5mm. A sealing interference in which compresses an elastomeric contact seal is generated by fastening a joint nut between two pipes. The FEM computed results show that the contact normal stress of contact model 1 with an inclined sealing surface is 1.5~1.75 times high in compared with that of contact model 2 with a parallel sealing surface. This indicates that the sealing contact surface recommends a wedge contact mode between two pipe connections for a high sealing compression stress.

• Korean Journal of Food Science and Technology
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• v.50 no.4
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• pp.357-361
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• 2018

This study aimed to explore efficient DNA extraction methods using tree nuts. Four different DNA extraction procedures, including silica membrane method, modified silica method, cetyltrimethylammonium bromide (CTAB) method, and modified CTAB method were examined for their relative efficiency in extracting DNA from pistachio, pine nut, almond, hazelnut, cashew nut, walnut, and peanut. The quality and quantity of the extracted DNA were subsequently assessed by spectrometric measurements, gel electrophoresis, and PCR amplifications. CTAB method was the most appropriate one for extracting DNA from pine nut, cashew nut, pistachio, and peanut. However, it could be replaced by the silica membrane method for walnut and modified CTAB method for almond and hazelnut.

• Journal of Korean Society of Steel Construction
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• v.12 no.3 s.46
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• pp.259-268
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• 2000

In the friction-type joints the external applied load is transmitted by frictional force acting on the contact area of the plates fastened by the high strength bolts. This frictional force is proportional to the product of the bolt clamping force and slip coefficient of the faying surface. But the bolt clamping force is dependent on many factors when the turn-of-nut method is used. The preserved thread length and length-to-diameter ratios are one of the major factors governing the bolt clamping force. This paper presents the correct method of high strength bolt tightening through the experiment on the mechanical properties on sets of high strength bolts in accordance with preserved thread length and length-to-diameter ratios.