Comparison of Ipsilateral Breast Tumor Recurrence Rate between Re-Excision and Radiotherapy Only Group When Surgical Margin Involvement of DCIS after Breast-Conserving Surgery

Hyunjun Lee(이현준),Jun-Hee Lee,Jae Min Ryu,Se Kyung Lee,Jonghan Yu,Jeong Eon Lee,Seok Won Kim,Seok Jin Nam,Byung Jioo Chae 대한외과학회 2021 대한외과학회 학술대회 초록집 Vol.2021 No.5

Observer design for exhaust gas recirculation rate estimation in a variable-geometry turbocharger diesel engine using a model reference identification scheme

Lee, Hyunjun,Park, Yeongseop,Sunwoo, Myoungho Professional Engineering Publishing Ltd 2014 Proceedings of the Institution of Mechanical Engin Vol. No.

<P>Exhaust gas recirculation systems are used in diesel engines to reduce nitrogen oxide emissions. Since excessive recirculation in the cylinders may lead to an increase in generation of particulate matter and to unstable combustion, the exhaust gas recirculation rate should be measured correctly and should be controlled precisely. Unfortunately, the harsh conditions of the exhaust gas recirculation path make it difficult to measure the exhaust gas recirculation mass flow rate directly by using the relevant sensors. Therefore, precise control of the exhaust gas recirculation system depends on accurate estimation of the exhaust gas recirculation rate. To estimate accurately the exhaust gas recirculation rate in a turbocharged diesel engine, we propose an observer based on a model reference identification scheme. A linear parameter-varying model of the intake manifold pressure was derived to serve as the observer’s reference model. An update rule of the observer was designed with the model reference identification scheme. The intake and exhaust temperature models were developed through an empirical approach. Convergence of the proposed observer was proven in terms of the Lyapunov stability criterion. The proposed observer was implemented on a real-time embedded system and validated successfully through experiments on the engine.</P>

Cylinder Pressure Information-Based Postinjection Timing Control for Aftertreatment System Regeneration in a Diesel Engine-Part II: Active Diesel Particulate Filter Regeneration

Lee, Hyunjun,Shin, Jaesik,Han, Manbae,Sunwoo, Myoungho ASME International 2016 Journal of engineering for gas turbines and power Vol.138 No.8

Quantification of economic uncertainty for synthetic natural gas production in a H₂O permeable membrane reactor as simultaneous power-to-gas and CO₂ utilization technologies

Lee, Boreum,Lee, Hyunjun,Kim, Sehwa,Cho, Hyun-Seok,Cho, Won-Chul,Jeon, Byong-Hun,Kim, Chang-Hee,Lim, Hankwon Elsevier 2019 ENERGY Vol.182 No.-

<P><B>Abstract</B></P> <P>Economic uncertainty analysis of employing a membrane reactor (MR) equipped with H<SUB>2</SUB>O separation membranes for a synthetic natural gas (SNG) production as simultaneous power-to-gas and CO<SUB>2</SUB> utilization technologies was carried out. Based on previously reported reaction kinetics, process simulation models were created for a conventional packed-bed reactor (PBR) and an MR. Deterministic economic analysis showed the unit SNG production cost of 1.67 $ kgSNG<SUP>−1</SUP> in an MR compared to 1.82 $ kgSNG<SUP>−1</SUP> in a PBR for a SNG production capacity of 1000 kg d<SUP>−1</SUP>, showing about 8% cost reductions in the MR. From sensitivity analysis, raw material and labor were identified as the key economic factors to affect a unit SNG production cost for all cases studied. Stochastic economic analysis using a Monte-Carlo simulation method provided better insights for economic-uncertainty associated with premature technology like a SNG production in an MR using H<SUB>2</SUB>O separation membranes by presenting a wide range of SNG production costs and their probability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A H<SUB>2</SUB>O permeable membrane reactor (MR) was proposed to improve SNG yield. </LI> <LI> Deterministic and stochastic economic analysis for SNG production were performed. </LI> <LI> For industrial-scale plant, the MR showed about 8% cost saving of a unit SNG cost. </LI> <LI> Uncertainty analysis presented a wide range of a unit cost from 1.01 to 2.28 $ kg<SUP>−1</SUP>. </LI> </UL> </P>

Gold nanostar-mediated neural activity control using plasmonic photothermal effects

Lee, Jee Woong,Jung, Hyunjun,Cho, Hui Hun,Lee, Jung Heon,Nam, Yoonkey Elsevier 2018 Biomaterials Vol.153 No.-

<P><B>Abstract</B></P> <P>Nanomaterials have emerged as an essential tool for the understanding of cellular level mechanism in the fields of biology and medical science. Recently, researchers have been studying the regulation of neuronal activity using plasmonic nanoparticles and light, and it has been reported that photothermal effects could lead to both excitation and inhibition of neuronal cells. So far, only a few photothermal transducers have been applied to modulate neural activity. In this paper, we synthesized biocompatible gold nanostars (AuNSs) which generate heat by absorbing near-infrared (NIR) light. And we used the AuNS to inhibit the activity of neurons through light stimulation. We have demonstrated that AuNS inhibits the neural activity by NIR laser in both chip-attached mode and cell-attached mode. We also confirmed the suppression of single neuron signal by using digital micromirror device (DMD) set up. This approach is possible to inhibit the neural firing by controlling the intensity of light, and overcome the disadvantages of conventional electrochemical stimulation methods. This method of NIR-mediated stimulating neurons using light sensitive AuNS will be a powerful tool for neuromodulation researches and neuroscience studies.</P>

Fault Diagnosis of Exhaust Gas Recirculation and Variable Geometry Turbocharger Systems in a Passenger Car Diesel Engine Based on a Sliding Mode Observer for Air System States Estimation

Lee, Hyunjun,Lee, Joonhee,Sunwoo, Myoungho ASME International 2014 Journal of Dynamic Systems, Measurement and Contro Vol.136 No.3

Development of Weeder Machine to Remove Furrow Weeds by Applying Circle Blade

( Hyunjune Lee ),( Subo Yang ),( Hwanggyu Lee ),( Hongmin Ahn ),( Jinhyun Kim ),( Taewook Kim ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

Removing the weeds from the furrow from the field crop cultivation should be carried out at an appropriate time. Most of the blade currently used in the flat shape and is not suitable for removing weeds from furrow. This research is to develop a weeder machine using a circle blade to efficiently remove weeds in the furrow. The geometric shape of the furrow was designed to develop the weeder machine. Circle blade shapes were based on the depth and width of the furrow from which the field crops were grown. Circle blade shapes were designed to fit the shape and size of the furrow so they would effectively remove weeds in the furrow. Weeder machine driving part is designed to drive a 300mm wheel using a differential gear on the engine’s power extraction device. And the auxiliary wheel was applied to the front of the weeder machine to adjust the height of weeder machine. In the weeding part, a designed by arranging two circle blades in pairs. Depending on the size of the furrow, the angle of placement for the circle blade was designed from 60 to 120 degrees.Power transmission is accomplished by distributing power to both sides using bevel gears. Blade rotation and driving tests were conducted. The optimum circle blades rotation speed of weeder machine drive speed were measured. As a result, it was judgement that the running speed of 4km/h was most suitable at the rotation speed of 3,000~4,000rpm.

Displaced subdivision surfaces of animated meshes

Lee, Hyunjun,Ahn, Minsu,Lee, Seungyong Elsevier 2011 Computers & graphics Vol.35 No.3

<P><B>Abstract</B></P><P>This paper proposes a novel technique for converting a given animated mesh into a series of displaced subdivision surfaces. Instead of independently converting each mesh frame in the animated mesh, our technique produces displaced subdivision surfaces that share the <I>same</I> topology of the control mesh and a <I>single</I> displacement map. We first propose a conversion framework that enables sharing the same control mesh topology and a single displacement map among frames, and then present the details of the components in the framework. Each component is specifically designed to minimize the shape conversion errors that can be caused by enforcing a single displacement map. The resulting displaced subdivision surfaces have a compact representation, while reproducing the details of the original animated mesh. The representation can also be used for efficient rendering on modern graphics hardware that supports accelerated rendering of subdivision surfaces.</P> <P><B>Graphical abstract</B></P><P>Conversion results of our methods. RMSEs are visualised as colors.<ce:figure id='f0065'></ce:figure></P><P><B>Highlights</B></P><P>► We propose a conversion method for animated meshes to displaced subdivision surfaces. ► Output meshes share the same control mesh connectivity and a single displacement map. ► The representation requires less storage and supports efficient rendering on GPU. ► Experimental results show our framework generates small shape conversion errors.</P>

Predictable Values of Decompressive Craniectomy in Patients with Acute Subdural Hematoma: Comparison between Decompressive Craniectomy after Craniotomy Group and Craniotomy Only Group

Hyunjun Kim,Sang Jun Suh,Ho-Jun Kang,이민석,Yoon-Soo Lee,Jeong-Ho Lee,Dong-Gee Kang 대한신경손상학회 2018 Korean Journal of Neurotrauma Vol.15 No.1

Objective: Patients with traumatic acute subdural hematoma (ASDH) often require surgical treatment. Among patients who primarily underwent craniotomy for the removal of hematoma, some consequently developed aggressive intracranialhypertension and brain edema, and required secondary decompressive craniectomy (DC). To avoid reoperation, we investigated factors which predict the requirement of DC by comparing groups of ASDH patients who did and did not requireDC after craniotomy. Methods: The 129 patients with ASDH who underwent craniotomy from September 2007 to September 2017 were reviewed. Among these patients, 19 patients who needed additional DC (group A) and 105 patients who underwent primarycraniotomy only without reoperation (group B) were evaluated. A total of 17 preoperative and intraoperative factors wereanalyzed and compared statistically. Univariate and multivariate analyses were used to compare these factors. Results: Five factors showed signifcant differences between the two groups. They were the length of midline shifting tomaximal subdural hematoma thickness ratio (magnetization transfer [MT] ratio) greater than 1 (p<0.001), coexistence of intraventricular hemorrhage (IVH) (p<0.001), traumatic intracerebral hemorrhage (TICH) (p=0.001), intraoperative fndingsshowing intracranial hypertension combined with brain edema (p<0.001), and bleeding tendency (p=0.02). An average valueof 2.74±1.52 was obtained for these factors for group A, which was signifcantly different from that for group B (p<0.001). Conclusion: An MT ratio >1, IVH, and TICH on preoperative brain computed tomography images, intraoperative signsof intracranial hypertension, brain edema, and bleeding tendency were identifed as factors indicating that DC would berequired. The necessity for preemptive DC must be carefully considered in patients with such risk factors Objective: Patients with traumatic acute subdural hematoma (ASDH) often require surgical treatment. Among patientswho primarily underwent craniotomy for the removal of hematoma, some consequently developed aggressive intracranialhypertension and brain edema, and required secondary decompressive craniectomy (DC). To avoid reoperation, we investigated factors which predict the requirement of DC by comparing groups of ASDH patients who did and did not requireDC after craniotomy. Methods: The 129 patients with ASDH who underwent craniotomy from September 2007 to September 2017 were reviewed. Among these patients, 19 patients who needed additional DC (group A) and 105 patients who underwent primarycraniotomy only without reoperation (group B) were evaluated. A total of 17 preoperative and intraoperative factors wereanalyzed and compared statistically. Univariate and multivariate analyses were used to compare these factors. Results: Five factors showed signifcant differences between the two groups. They were the length of midline shifting tomaximal subdural hematoma thickness ratio (magnetization transfer [MT] ratio) greater than 1 (p<0.001), coexistence of intraventricular hemorrhage (IVH) (p<0.001), traumatic intracerebral hemorrhage (TICH) (p=0.001), intraoperative fndingsshowing intracranial hypertension combined with brain edema (p<0.001), and bleeding tendency (p=0.02). An average valueof 2.74±1.52 was obtained for these factors for group A, which was signifcantly different from that for group B (p<0.001). Conclusion: An MT ratio >1, IVH, and TICH on preoperative brain computed tomography images, intraoperative signsof intracranial hypertension, brain edema, and bleeding tendency were identifed as factors indicating that DC would berequired. The necessity for preemptive DC must be carefully considered in patients with such risk factors

Some Features of Dye-sensitized Solar Cell Combining with Single-walled Carbon Nanotubes

Lee, Sanghun,Park, Hyunjune,Park, Taehee,Lee, Jongtaek,Yi, Whikun Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.3

A dye-sensitized solar cell (DSSC) was fabricated with a nanocrystalline $TiO_2$ film electrode on FTO glass, N719 dye, electrolytes (or $CsSnI_3$), and counter Pt electrode by incorporating it with single-walled carbon nanotubes (SWNTs). SWNTs were combined with $TiO_2$ film, $CsSnI_3$, Pt electrode, separately, and the SWNT-containing cell was compared with a pristine cell in cell performance. We also examined the performance change by pressing $TiO_2$ film, during cell fabrication, inside a high pressure chamber. Mostly, the change of conversion efficiency was compared for each cell, and an atomic force microscopy data were suggested to explain our results.