Effect of reduced cutaneous cues on motion perception and postural control.

Yi, Yongwoo,Park, Sukyung Springer-Verlag 2009 Experimental brain research Vol.195 No.3

<P>To investigate whether the sensory perception could be a more direct assessment of sensory deficit as oppose to the postural performance, we examined the effect of reduced cutaneous cues on motion perception and motion control. The subject was translated in a mediolateral direction with a single sinusoidal acceleration at a stimulus frequency of 0.25 Hz with a peak acceleration magnitude ranging from 0.25 to 8 mG in the dark. Two different plantar cutaneous conditions were provided: the control condition (barefoot) and the reduced cutaneous condition (foot on a spongy surface). For each foot-sole sensory condition, the subject completed six sets of 33 randomly ordered translation stimuli. After each translational stimulus, the subject reported their perceived direction of motion by pressing a hand-held button. The center of pressure (COP) and joint kinematics of the quiet stance were also measured. The results showed a significant increase in perception threshold as well as COP variation in the anteroposterior direction in the reduced cutaneous cue trials. However, a non-significant increase in COP in the mediolateral direction was shown. Multivariate covariance analysis of joint kinematics showed changes in postural coordination, such as increased reliance on hip strategy under reduced cutaneous cues condition, that have not been differentiated by univariate measures. The observed discrepancy in the significance of the contribution of plantar cutaneous cues to the detection threshold and the COP variation implies that the 'perception' could provide more direct and sensitive assessment of the sensory degradation than the 'action'.</P>

Sensory reweighting model for translational motion perception

Yongwoo Yi,Sukyung Park 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.4

추가된 체성 감각에 의한 선형 운동 지각 변화

이용우(Yongwoo Yi),박수경(Sukyung Park) Korean Society for Precision Engineering 2011 한국정밀공학회지 Vol.28 No.6

When one sensor cannot provide information by sensory deficit or loss, the sensory information can be provided by substituting other sensors for the defected sensor. This sensory substation might be influence on the deteriorated motion perception that consists of multi-sensory information such as visual, vestibular and somatosensory information. In this study, to investigate whether the additional sensation by sensory substitution could be integrated into the motion perception, we examined the effect of substituted postural sway sensation on the directional perception of body movement. Deteriorated motion perception by the reduced plantar sensation was enhanced under sensory substitution condition that provided the body sway information as the plantar vibratory stimulus. These results imply that the additional sensation might be integrated into and improve the motion perception.

하지 허혈 유발에 따른 선형 운동 역치 변화

이용우(Yongwoo Yi),박수경(Sukyung Park) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.11

말초 신경 병변 환자들에게 하지 체성감각의 저하는 균형 능력 저하와 관련이 있다. 일반적으로 균형 능력은 운동 결과를 측정하여 평가하여 왔다. 그러나 인체 움직임은 다양한 감각 신호들이 통합된 운동 지각에 의해 유발된다. 따라서, 본 연구에서는 하지 체성감각의 저하는 운동 지각 능력 또한 저하시킬 것이라는 가정하에, 이를 확인하기 위하여 허혈에 의한 하지 체성 감각 저하를 유도하였고, 이때의 피부 감각 민감도 및 선형 운동 방향 지각 능력의 변화를 측정 하였다. 이 결과 발바닥 체성감각 저하 유도 시에는 운동 지각 역시 저하되었다. 그러나 운동 결과에 해당하는 압력 중심은 변화하지 않았다. 따라서, 운동 지각 측정이 체성 감각 저하를 조기 발견할 수 있는 평가 방법으로 사용될 수 있음을 확인하였다. The lower limb somatosensory deficit observed among peripheral neuropathy patients is partially related to the decline in their balance ability. In general, balance ability has been examined by measuring the postural response (i.e., action). However, body motion is induced by integrated multisensory cues (i.e., motion perception). In this study, we hypothesized that the reduced lower limb somatosensation might also lower motion perception. We induced lower limb sensory deficits through ischemia and then measured the cutaneous sensory sensitivity and directional motion perception. The sensory deficit was successfully induced, and it also lowered the motion perception. However, the center of pressure (COP) variation did not significantly change under the sensory deficit. This result implies that measuring motion perception could enable the detection of precursors of sensory deficits.

다이오드 여기 녹색광 레이저 개발

이용우,이종훈,김광석 嶺南大學校基礎科學硏究所 2001 基礎科學硏究 Vol.21 No.-

Diode pumped solid-state laser has very long lifetime and high efficiency compared with flashlamp pumped laser. We developed a highly efficient and miniature size green laser using an intra-cavity frequency doubling scheme. A Nd:YVO_4 crystal was end-pumped by a single diode with 808 ㎚ wavelength to generate infrared beam. When we used a KTP crystal for frequency doubling, we obtained green power more than 100 mW.

8-(Tosylamino)quinoline inhibits tumour progression through targeting phosphoinositide-3-kinase/Akt pathway.

Jung, Yongwoo,Yi, Young-Su,Yoo, Dae Sung,Kim, Ji Hye,Yang, Woo Seok,Lee, Jongsung,Park, Kye Won,Kweon, Dae-Hyuk,Hong, Sungyoul,Cho, Jae Youl Govi-Verlag Pharmazeutischer Verlag [etc.] ; Verla 2013 PHARMAZIE Vol.68 No.2

<P>We examined whether 8-(tosylamino)quinoline (8-TQ), a structural analogue of BAY 11-7082, is able to modulate various tumourigenic responses using various in vitro and in vivo experimental conditions. 8-TQ exhibited the strongest suppressive activity on the proliferation of C6, A431, HeLa and MDA-MB-231 cells with IC550 values ranging from 10 to 30 microM. According to the analysis of level of active caspase-3, and morphologies of C6, HeLa and MDA-MB-231 cells, it was revealed that 8-TQ is able to induce apoptosis. Furthermore, this compound strongly diminished the invasion of MDA-MB-231 cells, the migration of HeLa cells, and the new generation of blood vessels under non-toxic conditions. Reduction of the phospho-form levels of intracellular signalling enzymes by 8-TQ strongly indicated that molecular signalling machineries composed of phosphoinositide 3-kinase (PI3K)/phosphoinositide-dependent kinase-1 (PDK1)/Akt and extracellular-signal-regulated kinase (ERK) could be targeted by 8-TQ treatment. Indeed, the specific inhibitors (LY294002 and U0126) of PI3K/PDK1/Akt and ERK showed similar anti-cancer properties to 8-TQ. Finally, 8-TQ intraperitoneally injected suppressed the increase of tumour volume up to 40% compared to vehicle-treated control. Taken together, our results clearly suggest that 8-TQ might have applications as a novel anti-cancer drug or may be served as a lead compound to be further optimized.</P>

녹색광 레이저의 출력 안정화 연구

이용우,이종훈 嶺南大學校基礎科學硏究所 2002 基礎科學硏究 Vol.22 No.-

We tried to reduce laser power fluctuation due to beating between multi longitudinal modes. Single longitudinal mode lasing was achieved by using a simple etalon made by cover-glass and it dramatically reduced laser fluctuation from 49% to 10%.

Selective Activation of Methane on Single-Atom Catalyst of Rhodium Dispersed on Zirconia for Direct Conversion

Kwon, Yongwoo,Kim, Tae Yong,Kwon, Gihun,Yi, Jongheop,Lee, Hyunjoo American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.48

<P>Direct methane conversion into value-added products has become increasingly important. Because of inertness of methane, cleaving the first C–H bond has been very difficult, requiring high reaction temperature on the heterogeneous catalysts. Once the first C–H bond becomes activated, the remaining C–H bonds are successively dissociated on the metal surface, hindering the direct methane conversion into chemicals. Here, a single-atom Rh catalyst dispersed on ZrO<SUB>2</SUB> surface has been synthesized and used for selective activation of methane. The Rh single atomic nature was confirmed by extended X-ray fine structure analysis, electron microscopy images, and diffuse reflectance infrared Fourier transform spectroscopy. A model of the single-atom Rh/ZrO<SUB>2</SUB> catalyst was constructed by density functional theory calculations, and it was shown that CH<SUB>3</SUB> intermediates can be energetically stabilized on the single-atom catalyst. The direct conversion of methane was performed using H<SUB>2</SUB>O<SUB>2</SUB> in the aqueous solution or using O<SUB>2</SUB> in gas phase as oxidants. Whereas Rh nanoparticles produced CO<SUB>2</SUB> only, the single-atom Rh catalyst produced methanol in aqueous phase or ethane in gas phase.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2017/jacsat.2017.139.issue-48/jacs.7b11010/production/images/medium/ja-2017-11010p_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja7b11010'>ACS Electronic Supporting Info</A></P>

Q-switching of a diode-pumped Nd:YVO4 laser with a closely folded resonator

Hyuncheol Lee,Yongwoo Lee,Chonghoon Kwak,Jinhyuk Kwon,Jonghoon Yi,Yong-Sik Lim 한국광학회 2005 Current Optics and Photonics Vol.9 No.2

A diode-pumped Nd:YVO4 laser is developed. The laser has a closely folded resonator. The laser beam in two arms of the folded resonator passes the same acousto-optic modulator. The laser output power and pulsewidth dependence on a Q-switching frequency were measured. It is found that the newly proposed geometry provides an effective means for reducing the pulsewidth while maintaining almost the same output power compared with the usual folded resonator, where the beam in one arm of the resonator passes the acousto-optic modulator.

Immunomodulatory effect of -rich fraction on Macrophage Functions

Yanyan Yang,Tao Yu,Yongwoo Jung,Man Hee Rhee,Yi-Seong Kwak,Chae Kyun Kim,Jae Youl Cho 고려인삼학회 2011 고려인삼학회 학술대회 Vol.2011 No.4