• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.1
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• pp.113-121
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• 2007

Commonly, in the Sensor Network that composed with multiple nodes uses Ad-hoc protocol to communicate each other. Each sensed data packets are collected by base node and processed by Host PC. But the Ad-hoc protocol is too vulnerable to Sinkhole attack, where the intruder attracts surrounding nodes with unfaithful routing information, and then performs selective forwarding or changes the data passing through it. The Sinkhole attack increases overhead over the network and boosts energy consumption speed to decrease network's life time. Since the other attacks can be easily adopted through sinkhole attack, the countermeasure must be considered carefully. In this paper, we proposed the Hop-depth algorithm that detects intruder in Sinkhole attack and colluded nodes. First, the proposed algorithm makes list of suspected nodes and identifies the real intruder in the suspected node list through the Hop-depth count value. And recalculates colluder's path information to find the real intruder. We evaluated the performance of the proposed algorithm using NS2. We compared and analyzed the success ratio of finding real intruder, false positive ratio, false negative ratio, and energy consumption.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.29-36
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• 2008

In this paper, mechanical reliability issues of copper through-wafer interconnections are investigated numerically and experimentally. A hermetic wafer level packaging for MEMS devices is developed. Au-Sn eutectic bonding technology is used to achieve hermetic sealing, and the vertical through-hole via filled with electroplated copper for the electrical connection is also used. The MEMS package has the size of $1mm{\times}1mm{\times}700{\mu}m$. The robustness of the package is confirmed by several reliability tests. Several factors which could induce via hole cracking failure are investigated such as thermal expansion mismatch, via etch profile, and copper diffusion phenomenon. Alternative electroplating process is suggested for preventing Cu diffusion and increasing the adhesion performance of the electroplating process. After implementing several improvements, reliability tests were performed, and via hole cracking as well as significant changes in the shear strength were not observed. Helium leak testing indicated that the leak rate of the package meets the requirements of MIL-STD-883F specification.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.75-75
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• 2010

3D 패키징 기술은 전기소자의 소형화, 고용량화, 저전력화, 높은 신뢰성등의 요구와 함께 그 중요성이 대두대고 있다. 이러한 3D 패키징의 연결방법은 와이어 본딩 또는 플립칩등의 기존의 방법에서 TSV(Through Silicon Via)를 이용하여 적층하는 방법이 주목받고 있다. TSV는 기존의 와이어 본딩과 비교하여 고집적도, 빠른 신호전달, 낮은 전력소비 등의 장점을 가지고 있어 많은 연구가 진행되고 있다. TSV의 세부 공정 중 비아필링(Via filling)기술은 I/O수 증가와 미세피치화에 따른 비아(Via) 직경의 감소 및 종횡비(Via Aspect Ratio)증가로 인해 기존 필링 공정으로는 한계가 있다. 기존의 비아 홀(Via hole)에 금속을 필링하기 위한 방법으로 전기도금법이 많이 사용되고 있으나, 전기도금법은 전기도금액 조성, 첨가제의 종류, 전류밀도, 전류모드 등에 따라 결과물에 큰 차이가 발생되어, 최적공정조건의 도출이 어렵다. 또한 20um이하의 비아직경과 높은 종횡비로 인하여 충진시 void형성등의 문제점이 발생하기도 한다. 본 연구에서는 용융솔더와 진공을 이용하여 비아를 필링시켰다. 이 방법은 관통된 비아가 형성된 웨이퍼 양단에 압력차를 주어, 작은 직경을 갖는 비아 홀의 표면장력을 극복하고, 용융상태의 솔더가 관통된 비아 홀 내부로 필링되는 방법이다. 관통 비아홀이 형성 된 웨이퍼 위에 솔더페이스트를 $250^{\circ}C$이상 온도를 가해 용융상태로 만든 후 웨이퍼 하부에 진공을 형성하여 필링하는 방법과 용융솔더를 노즐을 통하여 위쪽으로 유동시켜 그 위에 비아홀이 형성된 웨이퍼를 접촉하고 웨이퍼 상부에 진공을 형성하여 필링하는 방법으로 실험을 각각 실시하였다. 이 때, 웨이퍼 두께는 100um이하이며 홀 직경은 20, 30um, 웨이퍼 상부와 하부의 진공차는 약 0.02~0.08Mpa, 진공 유지시간은 1~3s로 실시하여 최적 조건을 고찰하였다. 각 조건에 따른 필링 후 단면을 전자현미경(FE-SEM)을 통해 관찰하였다. 실험 결과 0.04Mpa 이상에서 1s내의 시간에 모든 비아홀이 기공(Void)없이 완벽하게 필링되는 것을 관찰하였으며 이 결과는 기존의 방법에 비하여 공정시간을 감소시켜 생산성이 대폭 향상 될 수 있는 방법임을 확인하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.1
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• pp.29-36
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• 2007

Despite the role of tunnels in today's roadway environment, the study on tunnel lighting is still scant. Drivers passing through a tunnel face some difficulties caused by the visual differences between outside and inside of the tunnel. The whitehole phenomenon at a tunnel exit-zone severely decreases the driver's visibility in the daytime. A probeam lighting is generally recommended for the prevention of it. This paper simulates an exit-zone with a whitehole phenomenon to verify the effect of probeam lighting. Even though the tunnel lighting is important, it is not easy to consider enough number of lighting alternatives at the stage of tunnel design due to the complexity of tunnel conditions. This paper is expected to contribute improving the visibility in tunnels, especially at the exit-zone.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.125-130
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• 2019

A gas-spring has been used in many areas and its use is increasing because it can be designed for a range of purposes. In this study, the behavior of a piston with an orifice hole inside the gas-spring cylinder was predicted using computational fluid dynamics (CFD). The piston was designed to reduce the reaction force if the gas-spring is compressed and to move at a low speed when it is returned. The analysis showed that if the initial gas pressure in the gas-spring is increased to a certain level, the speed of the piston would not decrease with time but will remain constant. The effects of orifice hall size on the piston return speed were investigated. Reducing the size of the orifice hole will increase the pressure difference on both sides of the piston, reduce the piston speed, and make it more constant. On the assumption of a constant speed of the piston, a theoretical solution to the return speed of the piston was derived according to the initial gas pressure, and the results for several initial gas pressures were compared with those of CFD. Comparison studies showed similar results for both methods.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.43-53
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• 2020

The effect of the relative location between pre-swirl nozzle and receiver hole on the performance of radial on-board injection type pre-swirl system was analyzed. In this study, tendency of the change of discharge coefficient and temperature drop efficiency were analyzed for 20 design points through the combination of 5 pre-swirl nozzle location and 4 receiver hole location. Discharge coefficient of system tended to be similar to the pressure ratio of the pre-swirl nozzle. System performance variation occurred as the flow structure in the cavity was affected by the surface, and the influence of the stationary surface is greater than that of the rotating surface. Discharge coefficient of system changed -1.39% to 1.25% and temperature drop efficiency changed -5.41% to 2.94% refer to reference design point.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.3
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• pp.63-69
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• 2019

Soldering technology has been used in electronic industry for a long time. However, due to solder fatigue characteristics, automotive electronics are searching the semi-permanent interconnection technology such as press-fit method. Press fit interconnection is a joining technology that mechanically inserts a press fit metal terminal into a through hole in a board, and induces a strong bonding by closely contacting the inner surface joining of the through hole by plastic deformation of press-fit terminal. In this paper, the bonding properties of press-fit interconnection are investigated with PCB hole size and surface finishes. In order to compare interconnection reliability between the press fit and soldering, the change in resistance of the press-fit and soldering joints was observed during thermal shock test. After thermal cycling, the failure modes are investigated to reveal the degradation mechanism both press-fit and soldering technology.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.184-192
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• 2014

Various types of unit packaging methods were applied for 'Fuji' apples during short-term cold storage and export simulation. Gas tightness of the package was controlled stepwise in the successive two-year experiments using different perforation treatments (none, punch hole, or pinhole) and sealing methods (tie v s. heat seal). Risk of tight packaging and effectiveness of macroperforation on weight loss and quality maintenance were analyzed as related to changes in gas concentration inside the packages. Immediately after harvest, each 5 apple units were packaged in $40{\mu}m$ polypropylene (PP) film bags, stored 4 weeks at $0^{\circ}C$, and then put on the shelf for one week at ambient temperature in the preliminary experiment, In the main experiment, export process was imposed after storage simulating 2 week refrigerated container shipment at $0^{\circ}C$ plus one week local marketing at ambient temperature. Non-perforated film packaging with relatively high gas tightness induced flesh browning caused by carbon dioxide accumulation regardless of the sealing methods. Among perforated film packaging, in contrast, atmospheric modification was partly established only in the pinhole treatment and flesh browning symptom was not observed in all the treatments. Even the punch hole perforated film packaging without gas tightness effectively reduced the weight loss, whereas had slight benefits for quality maintenance. Reduced perforation using pinhole treatment seemed to improve sensory texture, while effects on physicochemical quality were insignificant. Overall results suggest the need of more minute perforation treatments on the packaging film to ensure modified atmosphere effects on quality maintenance.

• Journal of the Korean Magnetics Society
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• v.25 no.4
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• pp.117-122
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• 2015

The holes with a diameter of $35{\mu}m$ inside the GMR-SV (giant magnetoresistance-spin valve) film were patterned by using the photolithography process and ECR (electron cyclotron resonance) Ar-ion milling. From the magnetoresistance curves of the GMR-SV film with holes measuring by 4-electrode method, the MR (magnetoresistance ratio) and MS (magnetic sensitivity) are almost same as the values of initial states. On other side hand, the $H_{ex}$ (exchange bias coupling field) and $H_c$ (coercivity) dominantly increased from 120 Oe and 10 Oe to 190 Oe and 41 Oe as increment of the number of holes inside GMR-SV film respectively. These results were shown to be attributed to major effect of EMD (easy magnetic domian) having a region positioned between two holes perpendicular to the sensing current. On the basis of this study, the fabrication of GMR-SV applying to the hole formation improved the magnetoresistance properties having the thermal stability and durability of bio-device.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.271-274
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• 1992

본 논문은 판재상에 부품을 자동배치 하고 이를 최적으로 절단할 수 있도록 NC 프로그램을 자동 생성해 주는 네스팅 소프트웨어를 PC에서 구현한 내용을 기술하고 있다. 본 네스팅 소프트웨어에서는 부품의 자동배치에 비트 프로세싱 처리를 이용함으로써 계산 시간과 메모리 소모를 줄였으며 자유곡선을 포함한 2차원의 부품 내부에 홀이 있는 경우도 부품이 배치가 가능토록 하였다. 그리고 GUI 를 이용한 모든 처리를 WISIWTC 방식으로 이루어지도록 하였으며 부품 절단을 위한 각종 유틸리티와 한글을 사용한 도움 기능의 제공으로 사용자가 쉽게 사용 할 수 있도록 설계되었다.