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Somatodendritic organization of pacemaker activity in midbrain dopamine neurons
Jang Jinyoung,Kim Shin Hye,Um Ki Bum,Kim Hyun Jin,Park Myoung Kyu 대한약리학회 2024 The Korean Journal of Physiology & Pharmacology Vol.28 No.2
The slow and regular pacemaking activity of midbrain dopamine (DA) neurons requires proper spatial organization of the excitable elements between the soma and dendritic compartments, but the somatodendritic organization is not clear. Here, we show that the dynamic interaction between the soma and multiple proximal dendritic compartments (PDCs) generates the slow pacemaking activity in DA neurons. In multipolar DA neurons, spontaneous action potentials (sAPs) consistently originate from the axon-bearing dendrite. However, when the axon initial segment was disabled, sAPs emerge randomly from various primary PDCs, indicating that multiple PDCs drive pacemaking. Ca2+ measurements and local stimulation/perturbation experiments suggest that the soma serves as a stably-oscillating inertial compartment, while multiple PDCs exhibit stochastic fluctuations and high excitability. Despite the stochastic and excitable nature of PDCs, their activities are balanced by the large centrally-connected inertial soma, resulting in the slow synchronized pacemaking rhythm. Furthermore, our electrophysiological experiments indicate that the soma and PDCs, with distinct characteristics, play different roles in glutamate-induced burst-pause firing patterns. Excitable PDCs mediate excitatory burst responses to glutamate, while the large inertial soma determines inhibitory pause responses to glutamate. Therefore, we could conclude that this somatodendritic organization serves as a common foundation for both pacemaker activity and evoked firing patterns in midbrain DA neurons.
Smart Small Cell with Hybrid Beamforming for 5G: Theoretical Feasibility and Prototype Results
Jang, Jinyoung,Chung, MinKeun,Hwang, Seung Chan,Lim, Yeon-Geun,Yoon, Hong-jib,Oh, TaeckKeun,Min, Byung-Wook,Lee, Yongshik,Kim, Kwang Soon,Chae, Chan-Byoung,Kim, Dong Ku IEEE 2016 IEEE wireless communications Vol.23 No.6
<P>In this article, we present a real-time 3D hybrid beamforming approach for 5G wireless networks. One of the key concepts in 5G cellular systems is the small cell network, which settles the high mobile traffic demand and provides uniform user-experienced data rates. The overall capacity of the small cell network can be enhanced with the enabling technology of 3D hybrid beamforming. This study validates the feasibility of 3D hybrid beamforming, mostly for link-level performance, through the implementation of a real-time test-bed using a SDR platform and fabricated antenna array. Based on the measured data, we also investigate system-level performance to verify the gain of the proposed smart small cell system over LTE systems by performing system-level simulations based on a 3D ray-tracing tool.</P>
Steam Reforming of Toluene Over Ni/Coal Ash Catalysts: Effect of Coal Ash Composition
( Jinyoung Jang ),( Gunung Oh ),( Ho Won Ra ),( Sung Min Yoon ),( Tae Young Mun ),( Myung Won Seo ),( Jihong Moon ),( Jae-goo Lee ),( Sang Jun Yoon ) 한국화학공학회 2021 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.59 No.2
The development of a low cost catalyst with high performance and small amount of carbon deposition on catalyst from toluene steam reforming were investigated by using coal ash as a support material. Ni-loaded coal ash catalyst showed similar catalytic activity for toluene steam reforming compared with the Ni/Al<sub>2</sub>O<sub>3</sub>. At 800℃, the toluene conversion was 77% for Ni/TAL, 68% for Ni/KPU and 78% for Ni/Al<sub>2</sub>O<sub>3</sub>. Ni/TAL showed similar toluene conversion to Ni/Al<sub>2</sub>O<sub>3</sub>. However, Ni/KPU produced higher hydrogen yield at relatively lower toluene conversion. Ni/KPU catalyst showed a remarkable ability of suppressing the carbon deposition. The difference in coke deposition and hydrogen yield is due to the composition of KPU ash (Ca and Fe) which increase coke resistance and water gas shift reaction. This study suggests that coal ash catalysts have great potential for the application in the steam reforming of biomass tar.
Jinyoung Jang,Hyun-Sung Jung,Jumee Wang,Sukil Kim 대한신경정신의학회 2021 PSYCHIATRY INVESTIGATION Vol.18 No.1
Objective The aim of this study was to investigate the prevalence of depression and suicidal ideation among older Korean adults and the predictors of suicidal ideation. Methods We analyzed data from 5,604 Koreans aged 65 or older collected by the Korea National Health and Nutrition Examination Survey in 2012-2016, an annual national, cross-sectional, epidemiologic study of the Korean population. A chi-square test was used to assess differences in socio-demographic characteristics by suicidal ideation. Psychological variables, self-rated physical health, and the five dimensions of the Korean version of the EQ-5D (EuroQoL) were compared between four subgroups categorized according to the presence/absence of suicidal ideation and depression. Multiple logistic regression was used to estimate the predictive power of health-related quality of life variables, as well as physical and psychological factors regarding suicidal ideation. Results Overall, 11.5% of the sample reported suicidal ideation, and 20.0% of the suicidal ideation group were diagnosed with depression. Respondents with suicidal ideation had significantly lower levels of health-related quality of life than those without suicidal ideation. EQ-5D self-control (OR=1.42), anxiety/depression (OR=2.32), depression (OR=2.07), and self-rated physical health (OR=1.36) were found to significantly predict suicidal ideation. Conclusion Suicidal ideation without depression was prevalent among older Koreans. Self-control, anxiety/depression of EQ-5D, selfrated physical health, and depression predicted suicidal ideation. Interventions to screen older Koreans for early detection of suicide risk and prevention strategies should consider evaluating each EQ-5D dimension.
DME 예혼합 압축착화 엔진에서 배기가스 재순환의 영향
장진영(Jinyoung Jang),염기태(Kitae Yeom),배충식(Choongsik Bae) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The combustion and exhaust emission characteristics were investigated in an DME fueled HCCI engine with EEGR(external exhaust gas recirculation) and iEGR(internal exhaust gas recirculation). The effects of EEGR and iEGR on HCCI engine were compared each other under combustion and emission results. The effect of EEGR on HCCI engine was a contrary to the effect of iEGR. In case of increasing EEGR rate, start of auto-ignition was retarded and bum duration was extended. Due to these, indicated mean effective pressure was increased. Hydrocarbon(HC) and carbon monoxide(CO) were increased due to EEGR by low temperature of combustion. In case of increasing iEGR, start of auto-ignition was advanced and bum duration was reduced. Due to these, indicated mean effective pressure was decreased and pumping mean effective pressure was increased. HC and CO were decreased due to iEGR by increasing mixture temperature.
SI엔진에서 흡기밸브 개폐시기 변화와 배기스로틀이 잔류가스율과 배기가스 변화에 미치는 영향
장진영(Jinyoung Jang),염기태(Kitae Yeom),배충식(Choongsik Bae) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In-cylinder residual gas fraction(RGF) affects engine performance and emission characteristics. With RGF, the flame speed and maximum combustion temperature are decreased, which are deeply related with combustion stability particularly at idle and NOx emission at relatively high load, respectively. In this work, in-cylinder RGF was measured in a 2.0L Variable Valve Timing (VVT) SI engine for various intake valve timing, torque conditions. A Gas Chromatography (GC) and a high-speed solenoid valve were used for the sampling and measurement of CO₂ concentration. Increased valve-overlap resulted in an increased RGF and a decreased torque. At each operating conditions, RGF could be increased by applying the exhaust throttle. Those phenomena were liked to the back flow and pressure difference generated difference between intake and exhaust pressure during the valve overlap period.