• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.219-219
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• 2007

Ni stamper위에 100nm의 Si 코팅후 자기조립 단문자막(SAM)을 액상 코팅방식으로 형성 하였고, 내구성 및 열적 안정성을 검증하기 위해 반복적인 이형 및 압력인가test가 실시하였다. 20 회 이상의 이형실험을 통해 열적, 기계적 안정성을 확인하고, 접촉각 측정을 통해 이형특성의 안정성도 고찰하였다. 이를 Imprint공법을 적용 fine pattern의 구조물을 얻을수 있었다. SAM코팅은 TRICHLOROSILANE을 사용하였으며 Hexane과 1000:1의 비율로 섞어서 stirrer에서 mixing하는 방식을 사용했으며, UV-ozone처리를 통한 이형성 제거 효과도 관찰하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.209-209
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• 2007

Ni stamper위에 100nm의 Si 코팅후 자기조립 단분자막(SAM)을 액상 코팅방식으로 형성 하였고, 내구성 및 열적 안정성을 검증하기 위해 반복적인 이형 및 압력인가 test가 실시하였다. 20회 이상의 이형실험을 통해 열적, 기계적 안정성을 확인하고, 접촉각 측정을 통해 이형특성의 안정성도 고찰하였다. 이를 Imprint공법을 적용 fine pattern의 구조물을 얻을 수 있었다. SAM코팅은 TRICHLOROSILANE을 사용하였으며 Hexane과 1000:1의 비율로 섞어서 stirrer에서 mixing하는 방식을 사용했으며, UV-ozone처리를 통한 이형성 제거 효과도 관찰하였다.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.95-103
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• 2020

Purpose: The purpose of this study was to compare the axial displacement of the hexagonal and conical abutment in internal conical connection implant after screw tightening and cyclic loading. Materials and Methods: Internal conical connection implants were divided into two groups (n = 10): group HEX, hexagonal abutment; and group CON, conical 2-piece abutments. The axial displacement and removal torque values were measured after 30 Ncm torque tightening and 250N loading test of 100,000 cycles. The Student t test with 5% significance level was used to evaluate the data. Results: HEX group demonstrated significantly higher axial displacement values after 30 Ncm tightening in comparison to the CON group (P < 0.05). No significant difference was found in axial displacement after cyclic loading (P = 0.052). Removal torque loss before and after the cyclic loading both revealed no significant difference between groups (P = 0.057 and P = 0.138). Removal torque value decreased after cyclic loading in both groups (P < 0.05). Conclusion: Overall, both abutment with or without hexagon index presented similar biomechanical performance except HEX group demonstrated significantly more axial displacement after applying tightening torque.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.156-159
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• 2002

2차원 감성 모형에서는 중립 감성이라는 것이 존재하지 않지만, 인간이 생활에서 느끼는 감성은 중립 감성이 상당 부분을 자치한다. 따라서 인간의 감성 변화를 정확히 파악하기 위해서는 중립 감성에 대한 이해가 필수적이다. 본 연구에서는 5명의 뇌파 출현량을 반복적으로 측정함으로써 중립 감성의 개인내 안정성과 개인간 차이를 살펴보았다. 그 결과 $\theta$파와 $\alpha$파는 개인내 안정성을 반영하였으며, $\delta$파와 $\beta$파는 개인간 차이를 반영하는 것으로 나타났다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1033-1039
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• 2012

Artificial joints are used when joints lose their function because of either the destruction or damage of the composing bones of the joints. To evaluate the primary stability of a femur-implant system, the relative displacement caused by a repeated load is measured immediately after the insertion of the artificial joint. For more accurate stability evaluation, the accurate measurement of the penetration displacement of the artificial joint to the bone and the rotation angle of the artificial joint is essential. In this study, to evaluate the primary stability of the femur-implant system, we propose a new relative displacement measurement method. By using this new method, we comparatively evaluate the primary stability for various surgical methods and the varying stiffness of the cadaver femur-implant itself.

• Development and Reproduction
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• v.10 no.4
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• pp.263-269
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• 2006

To evaluate the potentiality of industrial use of cysteine proteinase inhibitor (cystatin) of tilapia egg and serum stability of the tilapia cystatin on low temperature storage and heat treatment was studied. When the eggs were stored at $4^{\circ}C$ for 3 days the cystatin activity was not changed much, while the supernatant of egg homogenate lost its cystatin activity significantly, remaining only about 65% of initial activity. When the eggs and serum were subjected to repeated freeze at $-20^{\circ}C$ and thaw at room temperature once a day, the egg cystatin was decreased after 5 cycles of freeze and thaw. However the serum cystatin was not changed by the 5 times repetition of freeze and thaw. More than 80% of egg cystatin activity was remained when the egg was heated at $35^{\circ}C$ for 30 min, but less than 10% was remained when heated at $50^{\circ}C$. On the other hand, the serum cystatin was very resistant to heat, remaining about 74% after heating at as high as $80^{\circ}C$ for 30 min. In summary, the egg cystatin was more stable when stored as intact form of egg rather than as supernatant of homogenate when stored at refrigeration. Egg cystatin was relatively stable against repeated freeze-thaw, and serum was found to be more stable in cysteine proteinase inhibitory activity than egg. Egg cystatin was not very resistant to heat treatment, while serum cystatin was quite resistant to high temperature heat treatment. These results suggest that tilapia egg and serum, especially the serum, would be a useful source for cysteine proteinase inhibitor in surimi production.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.949-957
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• 2017

A laser-vision-based height measurement system is developed and implemented for the inspection of two-step variable valve lift module assemblies. The proposed laser-vision sensor module is designed based on the principle of laser triangulation. This paper summarizes the work on 3D point cloud data collection and height difference measurements. The configuration of the measurement system and the proposed height measurement algorithm are described and analyzed in detail. Additional measurement experiments on the height differences of valves and lash adjusters of a two-step variable valve lift module were implemented repeatedly to evaluate the accuracy and repeatability of the proposed measurement system. Experimental results show that the proposed laser-vision-based height measurement system achieves high accuracy, repeatability, and stabilization for the inspection of two-step variable valve lift module assemblies.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.606-606
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• 2012

최근 지구 환경변화에 따른 기후변화의 영향으로 이상홍수 발생의 위험성이 증가하고, 상습적으로 홍수피해가 반복되고 있다. 홍수피해의 원인 중 하나인 하천제방의 붕괴는 월류, 침식, 제체불안정, 구조물에 의한 파괴 등으로 구분되고 이 중 월류 및 침식은 제방 파괴의 주된 원인으로 최근 통계자료에 보고되고 있다. 제방붕괴의 주된 원인 중 하나인 침식파괴로부터 제방을 보호하기 위해 제내지 사면에 호안공을 설치하며, 하천설계기준 해설(2009)에서는 제방 또는 하안을 유수에 의한 파괴와 침식으로부터 직접 보호하기 위해 제방 앞비탈에 설치하는 구조물로 정의하고 있다. 특히 사행하천의 만곡부에서는 제방파괴의 위험성이 높을 뿐만 아니라 국부적으로 집중되는 유속분포는 제방의 안정성을 위협한다. 또한 원심력, 2차류(secondary flow) 등에 의한 수위상승 등에 의해 제방이 파괴되고 월류되어 홍수피해가 발생할 가능성이 큰 취약지점이라고 할 수 있다. 본 연구에서는 2차원 수치모형을 이용하여 만곡부 흐름 특성을 분석하고 수리실험을 통해 측정된 유속 및 수위분포 결과와 비교하여 분석하였다. 또한 수리실험에서 도출된 호안 붕괴 시의 흐름을 구현하여 호안 붕괴 시 국부유속 및 전단응력을 계산하고 만곡부 호안의 안정성을 위한 설계인자를 분석하였다. 연구결과로 제시된 만곡부 안정성을 위한 설계인자는 국외 호안공 설계식과 비교하여 국부유속 및 전단응력의 설계인자의 적합성을 검토하고 국내 만곡부 호안의 안정성 설계기법개발에 도움이 될 수 있는 설계인자를 제시하고자 한다.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.164-173
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• 2009

Purpose: The purpose of this study was to evaluate the effect of abutment material on screw-loosening before and after cyclic loading. Among the different materials of abutments, zirconia and metal abutment were used. Material and methods: Two types of implant systems: external butt joint(US II, Osstem Implant, Korea) and internal conical joint(GS II, Osstem Implant, Korea) were used. In each type, specimens were divided into two different kinds of abutments: zirconia and metal(n=5). The implant was rigidly held in a special holding to device ensure fixation. Abutment was connected to 30 Ncm with digital torque gauge, and was retightened in 30 Ncm after 10 minutes. The initial removal torque values were measured. The same specimens were tightened in 30 Ncm again and held in the cycling loading simulator(Instron, USA) according to ISO/FPIS 1480. Cycling loading tests were performed at loads 10 to 250 N, for 1 million cycles, at 14 Hz,(by subjecting sinusoidal wave from 10 to 250 N at a frequency of 14 Hz for 1 million cycles,) and then postload removal torque values were evaluated. Results: 1. In all samples, the removal values of abutment screw were lower than tightening torque values(30 Ncm), but the phenomenon of the screw loosening was not observed. 2. In both of the implant systems, initial and postload removal torque of zirconia abutment were significantly higher than those of metal abutment(P<.05). 3. In both of the implant systems, the difference in removal torque ratio between zirconia abutment and metal abutment was not significant(P>.05). 4. In metal abutments, the removal torque ratio of GS II system(internal conical joint system) was lower than that of US II system(external butt joint system)(P<.05). 5. In zirconia abutments, the difference in removal torque ratio between the two implant systems was not significant(P>.05). Conclusion: Zirconia abutment had a good screw joint stability in the condition of one million cycling loading.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.4
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• pp.281-287
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• 2016

Fiber Bragg grating (FBG) sensors are applied in structural health monitoring (SHM) in various application fields because of their ease of multiplexing and capability of performing absolute measurements. Moreover, the packaging methods of FBG sensors accelerate their commercialization rapidly. However, long-term SHM exposes the FBG sensors to cyclic thermal loads, and a investigation is required because it finally leads to the signal instability of the FBG sensors. In this study, the effects of sensor packaging methods two methods are generally used for the FBGs: (bonding both sides of the FBG or bonding the FBG directly on signal stability of FBG sensors are investigated. Tests are conducted on specimens in a thermal chamber, over a temperature range from $-20^{\circ}C$ to $60^{\circ}C$ for 300 cycles. Signal characteristics such as Bragg wavelength, light intensity and full width at half maximum are examined and are compared with those of the FBG sensors, obtained in a previous study under direct bonding conditions. From the comparison, it is observed that the FBG sensors with bonding on both sides of the FBG demonstrate higher signal stabilities when exposed to cyclic thermal loads during long-term SHM. Consequently, it guarantees more effectiveness when packaging the FBG sensors.