Interband Transitions in Monolayer and Few-Layer WSe₂ Probed Using Photoexcited Charge Collection Spectroscopy

Choi, Kyunghee,Lee, Kimoon,Yu, Sanghyuck,Oh, Sehoon,Choi, Hyoung Joon,Bae, Heesun,Im, Seongil American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.24

<P>Transition-metal dichalcogenides are currently under rigorous investigation because of their distinct layer-dependent physical properties originating from the corresponding evolution of the band structure. Here, we report the highly resolved probing of layer-dependent band structure evolution for WSe<SUB>2</SUB> using photoexcited charge collection spectroscopy (PECCS). Monolayer, few-layer, and multilayer WSe<SUB>2</SUB> can be probed in top-gate field-effect transistor platforms, and their interband transitions are efficiently observed. Our theoretical calculations show a great coincidence with the PECCS results, proving that the indirect Γ-K and Γ-Λ transitions as well as the direct K-K transition are clearly resolved in multilayer WSe<SUB>2</SUB> by PECCS.</P> [FIG OMISSION]</BR>

일본 프롤레타리아 영화 운동의 기원: 사사 겐주의 소형영화론과 이동영화론 고찰

최세훈 ( Choi Sehoon ) 세계문학비교학회 ( 구 한국세계문학비교학회 ) 2017 世界文學比較硏究 Vol.59 No.-

이 연구는 1927년을 전후하여 발생한 일본 프롤레타리아 영화 운동의 기원과 그 전개 과정을 고찰하기 위해 수행되었다. 이 시기 영화 애호 동인들은 『영화공장』, 『영화의 영화』 등의 동인지를 중심으로 해외 프로영화 이론과 실천 방식 등을 학습한다. 그 후 뜻을 같이하는 일부 동인들이 모여 일본프롤레타리아영화연맹(이하 프로영맹)을 창립하고, 영화를 통한 무산계급 해방 운동을 전개하겠다고 선언한다. 그러나 프로영맹은 1920년대 일본의 현실을 감안할 때 프로영화의 직접 제작 및 상영이 어렵다고 보고, 프로영화 이론 연구와 시나리오 창작 등의 문필 활동에 집중한다. 비슷한 시기 트렁크극장 영화반 맹원 사사 겐주는 9.5㎜ 소형촬영기를 휴대하고 노동쟁의 현장에 뛰어들어 소형영화를 제작 및 상영하는 성과를 올린다. 이러한 성과를 바탕으로 그는 소형영화론과 이동영화대의 창설을 제안한다. 프로영맹의 프로영화론은 무산대중과 영화의 관계를 좁히지 못했다는 한계로 인해 대내외적으로 많은 비판에 직면했고, 결국 나프 영화반과 통합을 결의하게 된다. 1927년을 전후하여 발생한 이 최초의 프로영화 논쟁은 이후 일본 프로영화 운동의 활동 방침을 정하는 중요한 계기가 되었다. This study aims at exploring the origin of the Nihon Proletaria film movement and its development during mid-1920s. In 1927-8, there were leftist film critics group published film magazines such as Eiga Kojo and Eiga Kaiho. They actively exchange Marx-Leninist film theories and scenarios among members. To actively engaged with Proletarian liberation movement, some of them decided to organize the Nihon Proletaria Eiga Renmei and declared that they will fight for the liberation of Proletariat in Japan. The Nihon Proletaria Eiga Renmei realized it is actually impossible to produce and project leftist films under high pressure of governmental censorship. To avoid possible suppressions from government, they strategically utilized the way of writing scenarios or introducing film theory from the West. Meanwhile, Sasa Genju who belonged to the Film unit of the Zen Nihon Musansha Geizutsu Renmei, kicked off filming scenes of strikes using toy-like-9.5㎜ camera. His achievement were praised by many leftist critics, accordingly Sasa wrote an articles proposing that why they need to take the concept of `Little cinema` and `Mobile film unit`. The Nihon Proletaria Eiga Renmei was attacked for being petit-bourgeoisie by members of the Zen Nihon Musansha Geizutsu Renmei because the Renmei`s policy could not bridged the gap between the general public and film for liberation of proletariat. Therefore, Nihon Proletaria Eiga Renmei decided to be merged by Zen Nihon Musansha Geizutsu Renmei for next step for liberation. This event seems significant because it was the first polemics between leftists film artists and, with the result, the policy of the proletarian film movement refined.

3㎚ 기술 노드에서 All-Carbon 기반 Interconnect Scheme 도입 시 회로 특성 분석

박세훈(Sehoon Park),최문정(Moonjeong Choi),최승열(Seoungyeol Choi),이예지(Yeji Lee),장원영(Wonyeong Jang),권경배(Kyungbae Kwon),전종욱(Jongwook Jeon) 대한전자공학회 2022 대한전자공학회 학술대회 Vol.2022 No.6

A mechanism for orbital angular momentum and giant spin-splitting in solids and nanostructures

Sehoon Oh,Hyoung Joon Choi 한국자기학회 2015 한국자기학회 학술연구발표회 논문개요집 Vol.2015 No.11

Successful treatment of an unusually large corneal epithelial inclusion cyst using equine amniotic membrane in a dog

Choi, Ul Soo,Labelle, Philippe,Kim, Sehoon,Kim, Jury,Cha, Jaegwan,Lee, Ki Chang,Lee, Hae-Beom,Kim, Nam-Soo,Kim, Min-Su Blackwell Publishing Ltd 2010 Veterinary ophthalmology Vol.13 No.2

<P>Abstract</P><P>A 10-year-old intact male Yorkshire Terrier was referred for investigation of a large raised and nonpainful corneal lesion oculus dexter. Clinical examination revealed a pale, translucent corneal mass, which occupied half of the corneal surface and measured 11 mm × 11 mm × 13 mm. The mass was removed by superficial keratectomy and equine amniotic membrane (AM) was transplanted into the large corneal defect to cover the wound and provide tectonic support for the remaining cornea. The mass was histologically confirmed as a corneal epithelial inclusion cyst. There was no evidence of recurrence or complication at the surgical site 100 days postoperatively. Corneal epithelial inclusion cysts are uncommon in dogs. Although superficial keratectomy is the recommended treatment for corneal inclusion cyst, the combination of superficial keratectomy and AM transplantation had to be considered as an alternative for repair of large corneal defects. This is the first case report of the combined application of AM and superficial keratectomy to successfully treat a corneal inclusion cyst in a dog.</P>

Surface pH buffering to promote degradation of mesoporous silica nanoparticles under a physiological condition

Choi, Eunshil,Kim, Sehoon Elsevier 2019 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.533 No.-

<P><B>Abstract</B></P> <P>Despite significant advancement of mesoporous silica nanoparticle (MSN)-based biomedical research, studies have not been done enough to understand biodegradability of functional MSNs for better clinical efficacy. Polyethyleneimine (PEI) is one of the mostly used surface functionalities of MSNs, owing to the amine-rich chemical composition and the well-known proton sponge effect. In this paper, we study degradation behaviors of PEI-coated MSNs (PEI-MSNs) under a neutral or acidic physiological condition in comparison to those of surface-uncoated or nonionic F-127-encapsulated MSNs. The results showed that the surface coating by PEI could promote particle degradation in both neutral and acidic phosphate buffered saline (PBS) solution (i.e., pH 7.4 and 5.0). Importantly, we demonstrated that the local pH buffering by the surface PEI could lead to a greater total degradation quantity of particles even in the acidic PBS solution. The PEI-induced pH buffering phenomenon was confirmed by using a fluorescent pH indicator dye, fluorescein, which was attached to the surface of PEI-MSNs (F-PEI-MSNs). The observed pH-insensitive fluorescing behavior of fluorescein attained by surface coating with PEI corroborates the buffering effect that minimizes the surface pH change regardless of the external pH. The presented results may offer a useful insight into the degradability of silica nanomaterials with PEI or related surface functionalities, especially in the acidic subcellular microenvironment.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

How Can Doxorubicin Loading Orchestrate in Vitro Degradation Behaviors of Mesoporous Silica Nanoparticles under a Physiological Condition?

Choi, Eunshil,Kim, Sehoon American Chemical Society 2017 Langmuir Vol.33 No.20

<P>In the field of drug-delivery research, mesoporous silica nanoparticles (MSNs) have received a great deal of attention because of their capability to load and release drug molecules through the internal mesopores. To maximize the biomedical applicability of MSN-based drug carriers, it is important to ensure their degradability in a physiological environment as well as to obtain MSNs with desirable physicochemical properties. We present in vitro degradability of drug-loaded MSNs (DMSNs) that contain an anticancer drug (doxorubicin) in the pores and are suspended in physiological media (i.e., PBS at 37 degrees C). To obtain comprehensive understanding of the degradation process of DMSNs, cargo free MSNs and nonporous solid silica nanoparticles (SSNs) were studied comparatively. Degradation of each particle was studied by using ICP, TEM, and gas sorption measurement and analyzed in terms of structural parameters, external particle surface dissolution, and acidity of the PBS. It is demonstrated for the first time that drug loading into the pores leads to better degradability of MSNs by combining each distinct advantage of bare MSNs and SSNs to make DMSNs simultaneously possess an initial degradation rate as fast as drug-unloaded MSNs and a total degradation quantity as high as SSNs. The presented data not only demonstrate a high biodegradability of MSN-based drug carriers but also provide new insights into their unique in vitro degradation pattern.</P>

Motion control of joystick interfaced electric wheelchair for improvement of safety and riding comfort

Choi, Jung Hyun,Chung, Younghun,Oh, Sehoon Elsevier 2019 Mechatronics Vol.59 No.-

<P><B>Abstract</B></P> <P>Nowadays powered wheelchairs are widely utilized to help people’s locomotion. However, many commercialized powered wheelchairs still provide unsatisfactory ride quality, which is mainly due to not-well-designed control algorithm. To address this issue, this paper proposes a motion control algorithm that can improve the safety and riding comfort of the user and can be easily implemented on a powered wheelchair.</P> <P>To design the controller in an intuitive way, locomotion mode of a wheelchair is suggested at first, which consists of the longitudinal mode and the rotational mode. Then, the motion reference generator, wheelchair motion observer and control algorithms are designed in this locomotion mode.</P> <P>Moreover, this locomotion mode-based motion control does not require encoders, which makes the implementation of the algorithm affordable for many commercialized wheelchairs.</P> <P>The detail of the controller and state observer is studied, and experimental results to verify the validity of the proposed controller and the state observer are explained.</P>

3D Feature Based Tracking using SVM

Sehoon Kim,Seungjoon Choi,Sungjin Kim,Sangchul Won 제어로봇시스템학회 2004 제어로봇시스템학회 국제학술대회 논문집 Vol.2004 No.8

Simultaneous Delivery of Electrostatically Complexed Multiple Gene-Targeting siRNAs and an Anticancer Drug for Synergistically Enhanced Treatment of Prostate Cancer

Choi, Eunshil,Yoo, Wonjae,Park, Jae Hyung,Kim, Sehoon American Chemical Society 2018 MOLECULAR PHARMACEUTICS Vol.15 No.9

<P>Simultaneous silencing of multiple apoptosis-related genes is an attractive approach to treat cancer. In this article, we present a multiple gene-targeting siRNA/drug delivery system for prostate cancer treatment with a high efficiency. Bcl-2, survivin, and androgen receptor genes involved in the cell apoptosis pathways were chosen as silencing targets with three different siRNAs. The colloidal nanocomplex delivery system (<10 nm in size) was formulated electrostatically between anionic siRNAs and a cationic drug (BZT), followed by encapsulation with the Pluronic F-68 polymer. The formulated nanocomplex system exhibited sufficient stability against nuclease-induced degradation, leading to successful intracellular delivery for the desired therapeutic performance. Silencing of targeted genes and apoptosis induction were evaluated in vitro on human prostate LNCaP-LN3 cancer cells by using various biological analysis tools (e.g., real-time PCR, MTT cell viability test, and flow cytometry). It was demonstrated that when the total loaded siRNA amounts were kept the same in the nanocomplexes, the simultaneous silencing of triple genes with co-loaded siRNAs (i.e., Bcl-2, survivin, and AR-targeting siRNAs) enhanced BZT-induced apoptosis of cancer cells more efficiently than the silencing of each single gene alone, offering a novel way of improving the efficacy of gene therapeutics including anticancer drug.</P> [FIG OMISSION]</BR>