조절스트레스와 조절유도량에 따른 측정 AC/A ratio의 변화

노재현,유동식,문병연,김상엽,조현국 한국안광학회 2022 한국안광학회지 Vol.27 No.4

Purpose: To investigate the variations in measured AC/A ratio depending on the accommodative stress and spherical powers for accommodative induction. Methods: The near lateral heterophoria and AC/A ratio were measured using the modified Thorington chart and the horizontal red Maddox rod after subjective refraction for 25 participants (7 males, 18 females, mean age 20.96±1.54). Then, after accommodative stress induced by watching a video for 30 min, near lateral heterophoria and AC/ A ratio were measured. For AC/A ratio measurements, +2.50 D, +2.00 D, +1.00 D, −1.00 D, −2.00 D, and −2.50 D of spherical lenses were used for accommodative induction, respectively. Results: As a result of comparing the AC/A ratio measured before and after accommodative stress, there was no statistically significant difference between the two conditions. However, in case of AC/A ratio measured by the (+) powers, the AC/A ratio decreased as the (+) power increased. In case of AC/A ratio measured by the (-) powers, the AC/A ratio increased as the (−) power increased, and as a result of comparing the AC/A ratio measured at ±2.50 D, ±2.00 D, and ±1.00 D, there was a statistically significant difference at ±2.50 D (p<0.05) between two conditions. As a result of analyzing the correlation between the AC/A ratio measured before/after the accommodative stress and lateral heterophoria, there was no significant difference between the AC/A ratio and lateral heterophoria before the accommodative stress. After accommodative stress, there was a significant difference between the AC/A ratio measured with +2.50 D and +2.00 D and the lateral heterophoria (p<0.05). Conclusions: Tests related to AC/A ratio measurement and accommodation must be performed by maintaining a state of accommodation relaxation before the test. 목적: 조절스트레스와 조절유도량 변화가 AC/A ratio 측정값에 미치는 변수에 대해 분석하였다. 방법: 25명의 대 학생(남자 7명, 여자 18명, 평균연령 20.96±1.54세)을 대상으로 굴절이상 교정 후 수정된 토링톤시표와 수평방향 레 드마독스로드를 이용하여 근거리 수평사위와 AC/A ratio를 측정하였다. 그리고 30분간 스마트폰 동영상 시청으로 조절스트레스를 유발시킨 후 근거리 수평사위와 AC/A ratio를 측정하였다. AC/A ratio 측정 시 조절자극을 위해 사 용된 구면굴절력은 +2.50 D, +2.00 D, +1.00 D 그리고 –1.00 D, –2.00 D, –2.50 D를 사용하였다. 결과: 조절스트레스 전·후 조건에서 측정된 AC/A ratio를 비교한 결과, 두 그룹 모두 통계적으로 유의한 차이를 보이지 않았다. 두 그룹 모두 (+)굴절력으로 측정한 AC/A ratio에서는 (+)굴절력이 증가할수록 AC/A ratio가 감소하였으며, (–)굴절력으로 측정한 AC/A ratio에서는 (–)굴절력이 증가할수록 AC/A ratio가 증가하였다. 그리고 두 그룹의 ±2.50 D, ±2.00 D, ±1.00 D에서 측정된 AC/A ratio를 비교한 결과, ±2.50 D에서 통계적으로 유의한 차이를 보였다(p<0.05). 조절스트 레스 전·후 측정된 AC/A ratio와 사위와의 상관성을 분석한 결과, 조절스트레스 전 각 그룹의 AC/A ratio와 사위는 유의한 차이를 보이지 않았다. 조절스트레스 후 +2.50 D와 +2.00 D에서 측정된 AC/A ratio와 사위에서는 유의한 차이를 보였다(p<0.05). 결론: AC/A ratio 측정 및 조절과 관련된 검사에서는 반드시 검사 전 충분한 조절이완 상태 를 유지하여 검사해야 할 것이다.

Mice lacking adenylyl cyclase-5 cope badly with repeated restraint stress

Kim, Kyoung-Shim,Han, Pyung-Lim Wiley Subscription Services, Inc., A Wiley Company 2009 JOURNAL OF NEUROSCIENCE RESEARCH - Vol.87 No.13

<P>Physiological responses to acute stress proceed with the activation of the hypothalamus-pituitary-adrenal gland (HPA) system. Many brain regions are known to modulate the HPA axis activation in stress responses, but the detailed neural circuits and signaling system in the upstream of the HPA axis have to be explored further. Type 5 adenylyl cyclase (AC5) is highly concentrated in the dorsal striatum and nucleus accumbens, which are implicated in reward and stress-related behavior. AC5<SUP>–/–</SUP> mice exposed to daily 2-hr restraint stress for only 3–5 days showed poor stress-coping responses, including severe body weight loss, poor coat condition, respiratory difficulties, and freezing behavior. Plasma corticosterone levels during 2-hr stress sessions increased in AC5<SUP>–/–</SUP> mice compared with those of AC5<SUP>+/+</SUP> mice. However, neither the corticosterone receptor antagonist RU486 nor the CRH receptor antagonist NBI27914 blocked their poor stress coping, whereas the administration of the GABA<SUB>A</SUB> receptor allosteric modulator diazepam or the D1 dopamine receptor antagonist SCH23390 prior to restraint stress sessions changed their stress-coping response to the stressed AC5<SUP>+/+</SUP> mouse level. Stress-triggered c-Fos expression was completely blunted in the dorsal striatum of AC5<SUP>–/–</SUP>. These results suggest that the AC5-associated signal system and neural network are involved in the regulation of anxiety and stress-coping response. © 2009 Wiley-Liss, Inc.</P>

Profiling of ACC synthase gene (ACS11) expression in Arabidopsis induced by abiotic stresses

은희동,Sajid Ali,정현정,김기환,김원찬 한국응용생명화학회 2019 Applied Biological Chemistry (Appl Biol Chem) Vol.62 No.-

Abiotic stress induce the production of 1-aminocyclopropane-1-carboxylate (ACC), the precursor of ethylene by activating the enzyme ACC synthase. There are twelve ACC synthase genes reported in the genome of Arabidopsis, and the ACC synthase 11 (ACS11) gene encodes a polypeptide that is functional; however, its involvement in ethylene biosynthesis in response to abiotic stresses remains unclear. We evaluated the effects of higher ACC accumulation on A. thaliana seedlings in response to abiotic stressors such as flooding, salinity, cold, and drought. Transgenic plants were generated with ACS11 (ACS11-OX), and they demonstrated that overexpression of ACS11 reduces both root and shoot length observed in seedlings. RT-PCR analysis revealed that abiotic stressors induce the expression of the wild type ACS11 gene. Histochemical staining revealed that GUS activity followed the same time course as induction of wild type ACS11 gene expression, increased ACC levels, and production of stress hormone, ethylene. One finding showed that although induction of wild type ACS11 gene occurs under drought stress, GUS activity was highest at 6 h of drought stress and decreased to levels similar to control seedlings at 12 and 24 h. Thus, Wild type ACS11 expression is involved in ACC production, and abiotic stressors induce the expression of ACS11 gene. Moreover, ACC increases in response to abiotic stress lead to the production of ethylene. All of the data presented here suggest that the overexpression of ACS11 paves the way for the production of stress hormone, ethylene, which adversely affected the growth and development of the plant.

HT22 해마세포의 oxidative toxicity에 대한 천문동 유래 에탄올추출물의 보호 효과

박맑은(Malk Eun Pak),최병태(Byung Tae Choi) 한국생명과학회 2016 생명과학회지 Vol.26 No.12

본 연구는 oxidative stress에 의한 세포죽음 분석의 이상적인 모델로 사용되는 HT22세포를 이용하여 천문동 에탄올추출물의 glutamate에 의한 oxidative toxicity에 대한 신경보호 효과를 살펴보았다. 이를 위해 cell viability, lactate dehydrogenase (LDH), 그리고 세포죽음형태, reactive oxygen species (ROS), mitochondria membrane potential (MMP) 등에 대한 flow cytometry 및 Western blot분석을 이용하였다. 천문동 추출물의 처리는 cell viability 및 LDH분석에서 glutamate에 의한 cell toxicity를 저하시키며, 특히 apoptotic cell death를 현저히 감소시켰다. ROS 및 MMP분석 결과, 천문동 추출물은 ROS의 형성을 저하시키며 glutamate에 의해 저하된 MMP를 현저히 회복시켜 주었다. 이와 관련된 단백질 발현을 보면, 천문동 추출물은 PARP 및 HO-1의 발현을 억제하였다. 이상의 결과는 천문동 추출물이 HT22해마세포에서 ROS형성저해 및 MMP회복에 의해 세포죽음을 완화시켜 보호작용을 하는 것으로 사료되며 oxidative toxicity관련 질환에 적용 가능할 것으로 보여 진다. We investigated the neuroprotective effect of an ethanol extract from Asparagus cochinchinensis (AC) against glutamate-induced toxicity in the HT22 hippocampal cell, which is an ideal in vitro model for oxidative stress. The neuroprotective effects of AC in HT22 cells were evaluated by analyzing cell viability, lactate dehydrogenase (LDH), flow cytometry for cell death types, reactive oxygen species (ROS), mitochondria membrane potential (MMP), and Western blot assays. In the cell death analysis, AC treatment resulted in significantly attenuated glutamate-induced loss of cell viability with a decrease in LDH release. AC treatment also reduced glutamate-induced apoptotic cell death. In the ROS and MMP analysis, AC treatment inhibited the elevation of intracellular ROS induced by glutamate exposure and the disruption of MMP. In oxidative stress-related proteins analysis, AC treatment inhibited the expression of poly ADP ribose polymerase and heme oxygenase-1 by glutamate. These results indicate that AC exerts a significant neuroprotective effect against glutamate-induced hippocampal damage by decreasing ROS production and stabilizing MMP. Thus, AC potentially provides a new strategy for the treatment of oxidative stress-related diseases.

Al₂O₃-HfO₂-Al₂O₃와 SiO₂-HfO₂-SiO₂ 샌드위치 구조 MIM 캐패시터의 DC, AC Stress에 따른 특성 분석

곽호영,권혁민,권성규,장재형,이환희,이성재,고성용,이원묵,이희덕,Kwak, Ho-Young,Kwon, Hyuk-Min,Kwon, Sung-Kyu,Jang, Jae-Hyung,Lee, Hwan-Hee,Lee, Song-Jae,Go, Sung-Yong,Lee, Weon-Mook,Lee, Hi-Deok 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.12

In this paper, reliability of the two sandwiched MIM capacitors of $Al_2O_3-HfO_2-Al_2O_3$ (AHA) and $SiO_2-HfO_2-SiO_2$ (SHS) with hafnium-based dielectrics was analyzed using two kinds of voltage stress; DC and AC voltage stresses. Two MIM capacitors have high capacitance density (8.1 fF/${\mu}m^2$ and 5.2 fF/${\mu}m^2$) over the entire frequency range and low leakage current density of ~1 nA/$cm^2$ at room temperature and 1 V. The charge trapping in the dielectric shows that the relative variation of capacitance (${\Delta}C/C_0$) increases and the variation of voltage linearity (${\alpha}$/${\alpha}_0$) gradually decreases with stress-time under two types of voltage stress. It is also shown that DC voltage stress induced greater variation of capacitance density and voltage linearity than AC voltage stress.

AC7A 알루미늄 합금 금형의 응고과정에서 금형 내부에 발생하는 열변형에 대한 수치해석적 연구

오율권(Yoolkwon Oh),김용범(Yongbum Kim),양호동(Hodong Yang) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The manufacturing industry such as automobile tire must be changed to consult the tastes of customers and is required to make the finest product that it has improved more stability and driving performance at consumer's desire in a quick time. In the present study, AC7A aluminum alloy casting mold which consist of 8 pieces is introduced as an analysis model. Also, numerical work using a finite element method was applied to investigate the thermal deformation that included the temperature distribution, stress and strain during the cooling process in AC7A aluminum alloy casting mold. The numerical results such as temperature distributions, stress and strain are presented to help to make the effective and the best tire mold. In addition, the introduced technique of numerical work using a finite element method is very useful and especially needs to improve the precision of tire mold such as sectional type or puzzle type.

NO기반 게이트절연막 NMOS의 AC Hot Carrier 특성

장성근,김윤장,Chang, Sung-Keun,Kim, Youn-Jang 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.6

We studied the dependence of hot-tarrier-induced degradation characteristics on nitrogen concentration in NO(Nitrided-Oxide) gate of nMOS, under ac and dc stresses. The $\Delta$V$_{t}$ and $\Delta$G$_{m}$ dependence of nitrogen concentration were observed, We observed that device degradation was suppressed significantly when the nitrogen concentration in the gate was increased. Compared to $N_2$O oxynitride, NO oxynitride gate devices show a smaller sensitivity to ac stress frequency. Results suggest that the improved at-hot carrier immunity of the device with NO gate may be due to the significantly suppressed interface state generation and neutral trap generation during stress.ess.

The RMS Current Stress Reduction Technique in Link Capacitor of Two-stage AC/DC Converter

Du-Hee Jang,Cheol-Hee Yoo,Dong-Sung Oh,Sung-Soo Hong,Sang-Kyoo Han 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

The RMS (Root Mean Square) current reduction technique for the link capacitor of two-stage PFC (power factor correction) AC/DC converter is proposed. Although there exist various factors for optimizing the link capacitor, the RMS current stress is one of the most important factors to determine the capacitor size. To reduce the RMS current of the link capacitor, the main concept of the proposed method is by adding the small C-L-L-C filter around the link capacitor. Namely, the front C-L filter and rear L-C filter of proposed C-L-L-C filter can effectively reduce the RMS currents entering into and coming out of the link capacitor by filtering out the switching current components, respectively. Especially, since the crossover frequency of proposed filter is very far from that of the PFC converter, the proposed filter has hardly any effect on the dynamics of the AC/DC converter and thus, makes it easy to design the overall system controller. To confirm the validity of proposed filter, the theoretical analysis, design considerations, and experimental verification are presented.

Effects of DC and AC stress on the VT shift of AlGaN/GaN MIS-HEMTs

Kang Soo Cheol,Jung Hyun-Wook,Chang Sung-Jae,Choi Ilgyu,Lee Sang Kyung,Kim Seung Mo,Lee Byoung Hun,Ahn Ho-Kyun,Lim Jong-Won 한국물리학회 2022 Current Applied Physics Vol.39 No.-

AlGaN/GaN MIS-HEMTs with adjusted VT were fabricated using a recess gate to investigate the effect on actual operation when the polarity of the gate voltage is opposite in the on- and off-state. The direction and time exponents of VT shift depend on the polarity of the gate bias stress. Electrons detrapping from the Al2O3/AlGaN interface trap site to AlGaN under negative gate bias stress has to overcome the energy barrier, resulting in a higher temperature dependence. In addition, the unaffected gm and SS show that the degradation occurred primarily at the Al2O3/AlGaN interface rather than channel or mobility degradation. For unipolar and bipolar AC stresses, the time exponent of the VT shift during stress time has two values, and a relatively low value during relaxation after bipolar AC stress. These results may be due to the further degradation by Vmin at the broader energy levels of the Al2O3/AlGaN interface.

측정부 온도 부하에 따른 광용적맥파 파형 요동 특성 분석

이충근(Chungkeun Lee),신항식(Hangsik Shin) 대한전기학회 2015 전기학회논문지 Vol.64 No.2

Applicable range of Photoplethysmography (PPG) becomes wider as a non-invasive physiological measurement technique. However, PPG waveform is easy to be distorted by ambient light or vascular variation from temperature changes. Especially, irregular variation of PPG waveform caused by ambient temperature not only severely distorts the PPG, but also leads miss interpretation in clinical applications. Therefore, the investigation of between temperature and PPG waveform is quite important in using PPG. The purpose of this research is to quantify the PPG waveform characteristic and to investigate the waveform variation following the temperature change on measuring site. To quantify the fluctuation of PPG waveform, we use two techniques; detrended fluctuation analysis (DFA) and AC/DC analysis of PPG. We record PPG under temperature stress, which applied by medical use heat pack (40℃) and ice pack (0℃). Ten participants were applied to the experiment, and the result was evaluated to approve the temperature effect with statistical method, Wilcoxon signed rank test. The result shows that the AC component (p<0.05) and perfusion index DFS scale exponent (p<0.01) of PPG have the significance to temperature stress except for a DC component of PPG.