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Exposure to Stressors Facilitates Long-Term Synaptic Potentiation in the Lateral Habenula
Park, Hoyong,Rhee, Jeehae,Park, Kwanghoon,Han, Jung-Soo,Malinow, Roberto,Chung, ChiHye Society for Neuroscience 2017 The Journal of neuroscience Vol.37 No.25
<P>The lateral habenula (LHb) is a small part of the epithalamus that projects to monoamine centers in the brain. Previously, neurotrans-mission onto the LHb was shown to be abnormally potentiated in animal models of depression. However, synaptic plasticity in this brain area and the effect of stressor exposure on synaptic plasticity of the LHb have not been investigated. Thus, we explored whether the LHb undergoes dynamic changes in synaptic efficacy or not. First, we observed that a moderate LTP occurs in a fraction of LHb neurons obtained from naive Sprague Dawley rats. Interestingly, a single exposure to acute stressors, such as inescapable foot shock or restraint plus tail shock (RTS), significantly enhances the magnitude of LTP in the LHb. We also observed an increased number of LHb neurons expressing phosphorylated cAMP response element-binding protein (pCREB) after exposure to stressors, which may contribute to determine the threshold for LTP induction. LTP induction in the LHb resulted in an additional increase in the number of pCREB expressing neurons in stress-exposed animals but not in naive control animals. Together, we showed that LHb neurons have heterogeneous propensity for synaptic potentiation at rest; however, a single exposure to stressors greatly facilitates LTP induction in the LHb, suggesting that fundamental alterations in synaptic plasticity in the LHb may occur in animal models of depression or post-traumatic stress disorder.</P>
Minimum Wage Hike and Multinational Enterprises' Employment: Firm-Level Evidence from South Korea
Hoyong Jung,Sunyoung Park 세종대학교 경제통합연구소 2024 Journal of Economic Integration Vol.39 No.1
This study examines the impact of a consecutive double-digit hike in Korea's minimum wage from 2018 to 2019 after the impeachment of President Park Geun-hye as an exogenous shock on the employment of multinational enterprises (MNEs). Notably, this topic has received limited attention in extant literature. Using a firm-level dataset covering the period 2006-2020, we find that MNEs respond to increases in the minimum wage by reducing their total employment size, including both regular and temporary workers. Furthermore, the effects are heterogeneous and depend on the participation of international trade and strategic partnerships. Our findings indicate that the minimum wage policy can even lead to a decrease in high-quality jobs within high-productivity companies, underscoring the need to adjust the pace of such increases to mitigate their side effects on the labor market.
Parametric study on excitation temperature and electron temperature in low pressure plasmas
Hoyong Park,최원호 한국물리학회 2010 Current Applied Physics Vol.10 No.6
Thiswork aimsat investigation of the validity of the electron excitation temperature (Texc) byopticalemission spectroscopy (OES) as an alternative diagnostic to the electron temperature (Te). The excitation and the electron temperatureswere measured at a wide range of gas pressures and input powers in different plasmas such as capacitively-coupled, inductively-coupled, and magnetron direct current plasmas. As a result, both temperatures were found to decrease with an increase in pressure, whereas they not very dependent on power, indicating that Texc showed a tendency identical to that of Te as pressure and powerwere varied. This result suggests that Texc measurement can be an alternative diagnostic for Te measurement once the ratio of the two temperatures is found in advance through a calibration experiment especially for low pressure high electron density industrial processing plasmas in which probe measurements are limited.
Hoyong Hwang,Changhyun Lee,Jonghoon Park,Changkun Park IEEE 2014 IEEE transactions on microwave theory and techniqu Vol.62 No.11
<P>In this study, we propose an auxiliary power regulator (APR) for the current-shared cascade (CSC) structure of the driver stages of RF CMOS power. Although the CSC structure provides a method to reduce the power consumption at the driver stages of a differential power amplifier (PA), it is difficult to obtain optimum levels of effective supply voltage for the first and second driver stages. Additionally, the transistor sizes of the first and second driver stages of the CSC structure must be identical to ensure the proper operation of the PA. Thus, in this work, we propose an APR structure that ensures the proper operation of a PA with different transistor sizes in its first and second driver stages. To prove the feasibility of the proposed technique, we designed the PA with a CSC structure using an APR. From the measured results, we successfully verify the feasibility of the proposed structure. Additionally, we provide experimental results for a typical CMOS PA to determine the optimum supply voltage for the second driver stage.</P>
Hoyong Kim,Han-Seob Jeong,Seon-Hong Kim,Se-Yeong Park,Joon Weon Choi,In-Gyu Choi 한국산림바이오에너지학회 2020 산림바이오에너지 Vol.30 No.2
In this study, ethanol organosolv lignin (EOL) yield and structural characteristics of EOL depending on the production condition were evaluated to understand the lignin fractionation behavior and to determine the optimal condition for the production of phenolic compounds. EOL yield was enlarged until combined severity factor (CSF) reached 1.2, while molecular weight and nitrobenzene oxidation (NBO) yield of EOL were declined more than a half compare to those from CSF 0 to 0.6. Both EOL and NBO yields were predictable as a function of CSF with very high coefficient of determination. Concentration of phenolic compounds released from pyrolysis GC/MS was relatively stable until reaching CSF 1.5. However, it was significantly affected by not only CSF but also the concentration of acid used for the fractionation of EOL. Therefore, in order to produce phenolic compounds from EOL, production condition should be controlled between CSF 1.2 and 1.5 with low acid concentration.