• Journal of Mechanical Science and Technology
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• 제20권7호
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• pp.1012-1018
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• 2006

Diagnosis and treatment using the conventional flexible endoscope in gastro-intestinal tract are very common since advanced and instrumented endoscopes allow diagnosis and treatment by introducing the human body through natural orifices. However, the operation of endoscope is very labor intensive work and gives patients some pains. As an alternative, therefore, the capsule endoscope is developed for the diagnosis of digestive organs. Although the capsule endoscope has conveniences for diagnosis, it is passively moved by the peristaltic waves of gastro-intestinal tract and thus has some limitations for doctor to get the image of the organ and to diagnose more thoroughly. As a solution of these problems, various locomotive mechanisms for capsule endoscopes are introduced. In our proposed mechanism, the capsule-type microrobot has synchronized multiple legs that are actuated by a linear actuator and two mobile cylinders inside of the capsule. For the feasibility test of the proposed microrobot, a series of in-vitro experiments using small intestine without incision were carried out. From the experimental results, our proposed microrobot can advance along the 3D curved and sloped path with the velocity of about $3.29\sim6.26mm/sec$ and $35.1\sim66.7%$ of theoretical velocity. Finally, the proposed locomotive mechanism can be not only applicable to micro capsule endoscopes but also effective to advance inside of gastro-intestinal tract.

• 대한화학회지
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• 제10권4호
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• pp.166-174
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• 1966

cinnamoylated photosensitive polymer의 광증감 경화반응기구를 반응속도론적으로 연구했다. Cinnamic acid(C)와 증감제(S)의 first excited singlet and lowest triplet energy level diagram과 증감제의 농도증가에 따른 sensitivity의 포화 등의 사실로부터 이 반응의 주요과정은 C와 S의 광 energy흡수에 의한 $C^{*(1)}$ 및 $S^{*(1)}$로의 여기, $S^{*(1)}{\to}S^{*(3)}$ intersystem crossing, S의 excimer 형성, $S^{*(3)}{\to}C^{*(3)}$ energy transfer 그리고 $C^{*(3)}$와 C의 termination 등임을 가정하고 다음 반응속도를 구했다. $-\frac{d[C]}{dt} = \frac{K_1[C]}{K_2 + [C]}[\frac{I^c_{abs}}{K_3 + [S]} + \frac{K_4[C]}{(K_5 + [C])(K_6 + [S])}(I^s_{abs} + \frac{K_7I^c_{abs}[S]}{K_8 + [S]})]$ $I^c_{abs}$와 $I^s_{abs}$ ;C 및 S의 광흡수율 $K_n$;상수 적외선 흡수스펙트럼 분석의 결과, Cinnamoyl 에스테르화도와 sensitivity의 관계 및 증감제의 농도와 sensitivity의 관계에 대하여 발표된 실험 data는 윗식을 만족시키므로 가정한 반응기구에 대한 뒷받침을 얻었다.

• 생명과학회지
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• 제21권1호
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• pp.141-145
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• 2011

본 연구에서는 전사억제제(transcriptional inhibitor)로 알려진 actinomycin D가 전사조절인자(transcription factor)인 STAT의 인산화를 유도한다는 것을 확인하였다. Actinomycin D 처리 시 STAT1의 Tyr701, Ser727 인산화는 유도되지 않았지만 STAT3의 Tyr705 잔기의 인산화를 특이적으로 유도하는 것을 확인하였다. Actinomycin D에 의한 STAT3의 Tyr705 인산화 유도가 어떠한 기전을 통한 것인지 확인하기 위해서 관련 인자의 단백질 및 mRNA 발현을 확인한 결과 SOCS3의 단백질 및 mRNA 발현의 감소를 확인하였다. STAT3의 탈인산화를 유도한다고 알려진 tyrosine phosphatase인 SHP-1와 STAT의 upstream kinase인 JAK2의 인산화는 변화가 없었다. 또한 actinomycin D 뿐 아니라 다른 전사억제제인 DRB를 처리 하였을 경우에도 STAT3의 Tyr705 인산화가 유도되는 것을 확인하였다. 이상의 결과는 전사억제제에 의하여 특이적인 SOCS3 단백질 발현감소는 SOCS3의 하류의 target인 STAT3 인산화를 유도하였다.

• Structural Engineering and Mechanics
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• 제68권4호
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• pp.507-517
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• 2018

In this research the effect of bedding layer angle and bedding layer thickness on the shear failure mechanism of concrete has been investigated using PFC3D. For this purpose, firstly calibration of PFC3d was performed using Brazilian tensile strength. Secondly punch shear test was performed on the bedding layer. Thickness of layers were 5 mm, 10 mm and 20 mm. in each thickness layer, layer angles changes from $0^{\circ}$ to $90^{\circ}$ with increment of $25^{\circ}$. Totally 15 model were simulated and tested by loading rate of 0.016 mm/s. The results show that when layer angle is less than $50^{\circ}$, tensile cracks initiates between the layers and propagate till coalesce with model boundary. Its trace is too high. With increasing the layer angle, less layer mobilizes in failure process. Also, the failure trace is very short. It's to be note that number of cracks decrease with increasing the layer thickness. The minimum shear punch test strength was occurred when layer angle is more than $50^{\circ}$. The maximum value occurred in $0^{\circ}$. Also, the shear punch test tensile strength was increased by increasing the layer thickness.

• Computers and Concrete
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• 제15권1호
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• pp.37-54
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• 2015

In general, cracks significantly deteriorate the in-situ performance of concrete members and structures, especially in urban metro tunnels that have been embedded in saturated soft soils. The microcapsule self-healing method is a newly developed healing method for repairing cracked concrete. To investigate the optimal microcapsule parameters that will have the best healing effect in concrete, a 3D analytical probability healing model is proposed; it is based on the microcapsule self-healing method's healing mechanism, and its purpose is to predict the healing efficiency and healing probability of given cracks. The proposed model comprehensively considers the radius and the volume fraction of microcapsules, the expected healing efficiency, the parameters of cracks, the broken ratio and the healing probability. Furthermore, a simplified probability healing model is proposed to facilitate the calculation. Then, a Monte Carlo test is conducted to verify the proposed 3D analytical probability healing model. Finally, the influences of microcapsules' parameters on the healing efficiency and the healing probability of the microcapsule self-healing method are examined in light of the proposed probability model.

• 한국지능시스템학회논문지
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• 제16권5호
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• pp.601-607
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• 2006

본 논문은 칼만필터를 이용한 ZMP의 다음 상태 예측을 통한 새로운 이족로봇의 균형제어기법을 제안한다. 일반적으로 이족로봇의 동역학 모델은 3D-LIPM(3D-Linear Inverted Pendulum Mode)에 의해 수학적으로 근사화되지만, 이는 로봇의 동역학적 특성을 완벽하게 표현할 수 없다. 이족로봇의 안정성은 ZMP(Zero Moment Point) 위치가 안정영역에 존재하는 경우에 안정성이 보장된다. 그리고 로봇 구조와 그 모델 사이의 내재된 오차는 로봇의 안정성에 영향을 끼칠 수 있다. 그러므로 본 논문에서 제안하는 균형제어기법은 내부 오차를 줄일 수 있으며, 적절한 로봇의 제어가 가능하다. 제안된 균형제어기법의 실험은 다양한 상황을 포함한 가상의 공간상에서 모의실험 되었다.

• 대한금속재료학회지
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• 제46권5호
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• pp.310-314
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• 2008

Electromigration test of flip chip solder bump is performed at $140^{\circ}C$ C and $4.6{\times}10^4A/cm^2$ conditions in order to compare electromigration with thermomigration behaviors by using electroplated Sn-3.5Ag solder bump with Cu under-bump-metallurgy. As a result of measuring resistance with stressing time, failure mechanism of solder bump was evaluated to have four steps by the fail time. Discrete steps of resistance change during electromigration test are directly compared with microstructural evolution of cross-sectioned solder bump at each step. Thermal gradient in solder bump is very high and the contribution of thermomigration to atomic flux is comparable with pure electromigration effect.

• International Journal of Advanced Culture Technology
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• 제10권4호
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• pp.478-486
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• 2022

Holography is a human-friendly technology that can express 3D stereoscopic information without eye fatigue. You can experience the mysterious features of light directly and indirectly, and you can also experience the principles of 3D imaging, which makes it a very good curriculum. As such, although holography is very effective in teaching students optics and 3D imaging technology, it has not yet been systematically established. The reason is the cost burden such as expensive equipment and laboratories, and the lack of easily accessible educational equipment. We implemented a portable holographic recording system to solve this problem. In addition, since silver halides, which use harmful chemicals, are not used in the process of developing the recording medium, and photopolymers are used, it is possible to educate not only the general public but also young students. In order to improve the completeness of the recorded result, the mechanism part, light source, and recording medium part of the production system were newly constructed to complement all the existing problems. The proposed system will make holography easily accessible to many people in a variety of fields, not just education. Through the interesting experience of various features and principles of light and the production of holograms with high satisfaction, we hope to popularize them in various fields such as education.

• 한국해양환경ㆍ에너지학회지
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• 제1권2호
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• pp.82-95
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• 1998

이 논문에서는 LS/DYNA3D를 이용하여 다음과 같은 2가지 수치 시뮬레이션을 수행한다: 첫 번째 시뮬레이션은 310,000 DWT 이중선체 VLCC (피충돌선)과 35,000 및 105,000 DWT의 2척의 유조선(충돌선)들과의 충돌에 관한 경우로서, 충돌선들은 VLCC의 중심선에 직각으로 중앙부에 충돌하는 것으로 가정한다. 두 번째는 40,000 DWT급의 재래식과 개량식 이중선체 유조선의 선저구조의 2가지 모델, CONV/PD328과 ADH/PD328에 대한 좌초에 관한 시뮬레이션이다. 이 연구의 전체적인 목적은 이중선체 유조선의 선측 및 선저구조에 충돌 및 좌초가 각각 발생하는 동안에 이중선체의 내판이 찢어지기 시작하고 운동에너지가 소산되면서 선체가 정지되는 등의 구조적인 파손 및 흡수에너지의 역학적인 거동을 이해하는 것이다. 이러한 수치 시뮬레이션을 통하여 충돌 및 좌초시의 손상 정도를 쉽게 추정할 수 있을 것이고 유조선의 설계 시 안전도의 개선에 이바지할 수 있게 할 것이다.

• Biomolecules & Therapeutics
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• 제24권6호
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• pp.610-615
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• 2016

Quercetin, a flavonol, has been reported to exhibit a wide range of biological properties including anti-oxidant and anti-inflammatory activities. However, pharmacological properties of quercetin-3-O-${\beta}$-D-glucuronide (QG), a glycoside derivative of quercetin, have not been extensively examined. The objective of this study is to elucidate the anti-inflammatory property and underlying mechanism of QG in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells in comparison with quercetin. QG significantly suppressed LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and $PGE_2$, and pro-inflammatory protein expressions of iNOS and COX-2. To elucidate the underlying mechanism of the anti-inflammatory property of QG, involvement of MAPK signaling pathways was examined. QG significantly attenuated LPS-induced activation of JNK and ERK in concentration-dependent manners with a negligible effect on p38. In conclusion, the present study demonstrates QG exerts anti-inflammatory activity through the suppression of JNK and ERK signaling pathways in LPS-challenged RAW264.7 macrophage cells.