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Podocyte hypertrophy precedes apoptosis under experimental diabetic conditions.
Lee, Sun Ha,Moon, Sung Jin,Paeng, Jisun,Kang, Hye-Young,Nam, Bo Young,Kim, Seonghun,Kim, Chan Ho,Lee, Mi Jung,Oh, Hyung Jung,Park, Jung Tak,Han, Seung Hyeok,Yoo, Tae-Hyun,Kang, Shin-Wook Rapid Science Publishers ; Kluwer Academic Publish 2015 Apoptosis Vol.20 No.8
<P>Podocyte hypertrophy and apoptosis are two hallmarks of diabetic glomeruli, but the sequence in which these processes occur remains a matter of debate. Here we investigated the effects of inhibiting hypertrophy on apoptosis, and vice versa, in both podocytes and glomeruli, under diabetic conditions. Hypertrophy and apoptosis were inhibited using an epidermal growth factor receptor inhibitor (PKI 166) and a pan-caspase inhibitor (zAsp-DCB), respectively. We observed significant increases in the protein expression of p27, p21, phospho-eukaryotic elongation factor 4E-binding protein 1, and phospho-p70 S6 ribosomal protein kinase, in both cultured podocytes exposed to high-glucose (HG) medium, and streptozotocin-induced diabetes mellitus (DM) rat glomeruli. These increases were significantly inhibited by PKI 166, but not by zAsp-DCB. In addition, the amount of protein per cell, the relative cell size, and the glomerular volume were all significantly increased under diabetic conditions, and these changes were also blocked by treatment with PKI 166, but not zAsp-DCB. Increased protein expression of cleaved caspase-3 and cleaved poly (ADP-ribose) polymerase, together with increased Bax/Bcl-2 ratios, were also observed in HG-stimulated podocytes and DM glomeruli. Treatment with either zAsp-DCB or PKI 166 resulted in a significant attenuation of these effects. Both PKI 166 and zAsp-DCB also inhibited the increase in number of apoptotic cells, as assessed by Hoechst 33342 staining and TUNEL assay. Under diabetic conditions, inhibition of podocyte hypertrophy results in attenuated apoptosis, whereas blocking apoptosis has no effect on podocyte hypertrophy, suggesting that podocyte hypertrophy precedes apoptosis.</P>
Development of a Safe Manipulator using Spring-Clutches
SeongHun Hong,Junho Choi,Woosub Lee,Sungchul Kang,Hyeongcheol Lee 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10
For physical safety of a service robot, various safe mechanisms have been studied and developed. Most researches on safety concentrated on safe joint component, and experimental results in situations that the safety component is well-functioned in 1 joint level. In cases of multi-axis, however, there exist many constraints when the safe component is mounted to the multi-axis manipulator, for example, the weight and/or volume of the component, the degradation of the safety performance due to the influence of the gravity as the pose of manipulator. So, it is realistically difficult to develop the manipulator with the safety component. This paper presents a safe manipulator with safety component at each joint to overcome practical limitations. Through experiments of unconstrained and constrained collision, it is shown that a new safe manipulator is mechanically safe.
A Novel Method for the Accurate Evaluation of Poisson's Ratio of Soft Polymer Materials
Lee, Jae-Hoon,Lee, Sang-Soo,Chang, Jun-Dong,Thompson, Mark S.,Kang, Dong-Joong,Park, Sungchan,Park, Seonghun Hindawi Publishing Corporation 2013 The Scientific World Journal Vol.2013 No.-
<P>A new method with a simple algorithm was developed to accurately measure Poisson's ratio of soft materials such as polyvinyl alcohol hydrogel (PVA-H) with a custom experimental apparatus consisting of a tension device, a micro X-Y stage, an optical microscope, and a charge-coupled device camera. In the proposed method, the initial positions of the four vertices of an arbitrarily selected quadrilateral from the sample surface were first measured to generate a 2D 1st-order 4-node quadrilateral element for finite element numerical analysis. Next, minimum and maximum principal strains were calculated from differences between the initial and deformed shapes of the quadrilateral under tension. Finally, Poisson's ratio of PVA-H was determined by the ratio of minimum principal strain to maximum principal strain. This novel method has an advantage in the accurate evaluation of Poisson's ratio despite misalignment between specimens and experimental devices. In this study, Poisson's ratio of PVA-H was 0.44 ± 0.025 (<I>n</I> = 6) for 2.6–47.0% elongations with a tendency to decrease with increasing elongation. The current evaluation method of Poisson's ratio with a simple measurement system can be employed to a real-time automated vision-tracking system which is used to accurately evaluate the material properties of various soft materials.</P>
Development of Context-Aware Power Management Scheme Using Beacons
Lee, Kwang Ok,Lee, Seok Min,Jo, Seonghun,Park, Gyeong Ho,Kim, Se-Jin The Basic Science Institute Chosun University 2018 조선자연과학논문집 Vol.11 No.1
In this paper, we propose a context-aware power management (CPM) scheme using beacons to reduce the power consumption of personal computers (PCs). In the proposed CPM scheme, the PC, smartphone, control server, and Internet of Things (IoT) device are necessary. PC users first log in the control server using their smartphones and select PCs to turn on. Then, the selected PCs automatically go into three different modes, i.e., sleep, shutdown, and standby power off modes, in order when the PC users leave the PCs without turning off them. Further, we develop a testbed with the proposed CPM scheme using the Arduino with Bluetooth low energy (BLE) and relay modules. Finally, it is shown that the proposed CPM scheme outperforms the conventional scheme in terms of the power consumption.
Lee, Donggil,Lee, Kyounghoon,Pyeon, Yongbeom,Kim, Seonghun,Bae, Jaehyun The Korean Society of Fisheries and Ocean Technolo 2015 수산해양기술연구 Vol.51 No.2
Recently LED fish-attracting lamps have been more widely used in fisheries as low-cost and high-efficiency fishing gear, and development of long-life high-efficiency lamps is required through the design of LED packages to optimize heat resistance. This study developed an improved LED fish-attracting lamp with excellent heat performance, which was verified using a numerical model. Heat-resistance design factors such as the heat-radiation fin shape, PCB type, and LED chip count were investigated and optimized. Comparison with a commercial 180-W LED fishing lamp showed that the increase in initial temperature was 40% higher than that of the surrounding LED chip because of design errors in contact thermal resistance. The 250-W LED lamp developed in this study has a characteristic with thermal rising in linearly stable according to the heat source. In addition, luminance efficiency was improved by 20-65% by using flow-visualization simulation. A decrease of 45% in total power consumption with a fuel-cost reduction of over 55% can be expected when using these optimized heat release design factors.
Acoustic monitoring using multi-beam imaging sonar through a set net in the Southern Sea, Korea
Lee, Hyungbeen,Lee, Kyounghoon,Kim, Seonghun,Lee, Donggil,Yang, Yongsu Springer Japan KK 2016 Fisheries Science Vol.82 No.5
<P>This study investigated a method for monitoring fish flux though a set net in the coastal South Sea, Korea, using sideward-looking wide angle multi-beam imaging sonar (blueview). This data set was used to examine the impact of changes in diel variation and current speed from a set net. During nighttime, the influx of fish in the set net was significantly 22 times higher than in daytime. The time when high fish flux was observed corresponded to the time of low current speed during nighttime. In contrast, the fish flux was not affecting current speed during daytime. The study provides implications for understanding fish behavior through use of a set net.</P>
Lee, Jae-Hoon,Han, Changwan,Ahn, Dongsu,Lee, Jin Kyoo,Park, Sang-Hu,Park, Seonghun Hindawi Publishing Corporation 2013 The Scientific World Journal Vol.2013 No.-
<P>We designed and validated a rotary magnetorheological (MR) damper with a specified damping torque capacity, an unsaturated magnetic flux density (MFD), and a high magnetic field intensity (MFI) for unmanned vehicle suspension systems. In this study, for the rotary type MR damper to have these satisfactory performances, the roles of the sealing location and the cover case curvature of the MR damper were investigated by using the detailed 3D finite element model to reflect asymmetrical shapes and sealing components. The current study also optimized the damper cover case curvature based on the MFD, the MFI, and the weight of the MR damper components. The damping torques, which were computed using the characteristic equation of the MR fluid and the MFI of the MR damper, were 239.2, 436.95, and 576.78 N<I>·</I>m at currents of 0.5, 1, and 1.5 A, respectively, at a disk rotating speed of 10 RPM. These predicted damping torques satisfied the specified damping torque of 475 N<I>·</I>m at 1.5 A and showed errors of less than 5% when compared to experimental measurements from the MR damper manufactured by the proposed design. The current study could play an important role in improving the performance of rotary type MR dampers.</P>
이성훈 ( Seonghun Lee ),구경아 ( Kyung Ah Koo ),임창민 ( Changmin Im ),윤태경 ( Tae Kyung Yoon ) 한국환경영향평가학회 2021 환경영향평가 Vol.30 No.2
본 연구는 최근 국립공원을 찾는 사람들이 많아짐에 따라 국립공원 관리의 정책 방향을 검토·결정하는데 필요한 국립공원 이용·보전 관리에 대한 시민의 여론을 확인하고자 진행하였다. 지금까지 국립공원 이용 및 인식과 관련한 설문 조사, 빅데이터 분석 등이 수행됐으나 공원 관리의 쟁점 사항 및 이용에 관한 조사 문항 등이 부족하며 조사 대상이 탐방객으로 국한되는 등의 한계가 있었다. 따라서 시민들의 국립공원 이용과 현재 운영되고 있는 제도에 대한 인식을 확인하기 위해 일반 시민을 대상으로 설문 조사를 진행하였다. 연구결과 탐방객을 상대로 진행된 선행연구들과는 달리 일반 시민들은 고지대 탐방보다는 저지대 탐방을 선호하는 결과가 나타났다. 또한 국립공원에서는 산정부 탐방 금지 정책에 대해 일반 시민들은 현재의 정책을 유지하거나 탐방예약제를 소폭 도입하는 것을 선호하는 것으로 나타났다. 그리고 탐방예약제를 이용해본 시민들의 비율도 매우 적은 것으로 나타났다. 도출된 결과를 바탕으로 탐방객과 일반 시민의 차이점을 고찰하고 공원 관리 원칙과 방향성의 변화, 국민의식과 탐방형태의 변화에 따른 정책여건을 전망하였다. This study investigated the public opinion on the use and conservation management of national park, to manage the growing demand of national park visit and to support the policy direction of national park. So far, various surveys and big data analysis on the use and perception of national park have been conducted, but there have been limitations such as lack of survey questions on issues in park management and use. In addition, the object of the previous studies were limited to the national park visitors; therefore, this study expanded the object of survey from national park visitors to ordinary citizens. Unlike previous studies conducted only on national park visitors, ordinary citizens relatively prefered bottom areas rather than high-altitude ones. A policy to limit the visit to high-ridge area of mountain is being currently driven; however, the survey results of ordinary citizens suggested to maintain current policies or to increase visitor reservations system within narrow limits. On the other hand, the proportion of citizens who have used the visitor-reservation system was very small. We discuss the difference between national park visitors and ordinary citizens and the policy conditions according to changes in park management principles and public attitudes toward national parks.