Range-dependent geoacoustic inversion of vertical line array data using matched beam processing.

Kim, Kyungseop,Seong, Woojae,Lee, Keunhwa,Kim, Seongil,Shim, Taebo American Institute of Physics for the Acoustical S 2009 Journal of the Acoustical Society of America Vol.125 No.2

<P>This paper describes the results of range-dependent geoacoustic inversion using vertical line array data obtained from the 4th Matched Acoustic Properties and Localization Experiment conducted in the East Sea of Korea. The narrowband multitone continuous-wave signal from the towed source was analyzed to estimate the range-dependent geoacoustic properties along the radial track. The primary approach is based on the sectorwise inversion scheme. The inversion region up to 7.5 km from the vertical line array was divided into several segments, and the subinversions for each segment were performed sequentially. To reduce the dominance of low-angle arrivals, which bears little information for the bottom segment in question, matched beam processing with beam filtering was used for the cost function. The performance of proposed algorithm was tested using simulated data for an environment representative of the experimental site. The inversion results for the experimental data were consistent with the geophysical database and were validated from matched-field source localization using frequencies different from those used in the inversion.</P>

구형 하이드로폰의 가속도 감도 특성

김경섭(Kyungseop Kim),조치영(Cheeyoung Joh),서희선(Heeseon Seo),조요한(Yo-Han Cho) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.10

소나 음향센서의 진동유기 소음 차단 특성에 대한 실험적 연구

김경섭,제엽,김호준,조요한,이정민,김동현,장우석,Kim, Kyungseop,Je, Yub,Kim, Ho-Jun,Cho, Yo-Han,Lee, Jeong-Min,Kim, Donghyeon,Chang, Woosuk 한국음향학회 2019 韓國音響學會誌 Vol.38 No.2

본 논문에서는 선체부착형 음향센서의 플랫폼 진동유기 소음 차단 특성을 확인하기 위한 수중 진동 실험을 수행하고 결과를 분석하였다. 음향수조 환경에서 음향센서가 설치된 선체모사구조물과 가진기를 이용하여 플랫폼 진동유기 소음 조건을 구현하였고, 선체모사구조물 및 음향센서에 설치된 표준 가속도계와 음향센서의 출력신호 측정을 통해 음향센서의 진동차단율, 삽입손실 및 진동민감도와 같은 성능지수를 산출하였다. 산출된 성능지수 결과를 토대로 음향센서의 주파수별 소음 차단 특성을 분석하고 실험 기법의 유효성을 검토하였다. In this paper, the results of underwater vibration experiment are analyzed to verify platform vibration-induced noise isolation characteristics of a hull-mounted acoustic sensor. The experimental condition causing platform vibration-induced noise is generated using the mock-up hull, where the acoustic sensor is installed, with shaker in an acoustic water tank. The performance indices of ATF (Acceleration Transfer Function), AVS (Acceleration Voltage Sensitivity), and IL (Insertion Loss) for the acoustic sensor are calculated from the output of the standard accelerometers, which are installed on the mock-up hull and the acoustic sensor, and the output signal of the acoustic sensor. The frequency-dependent noise isolation characteristics of the acoustic sensor are analyzed based on the calculated performance indices and an effectiveness of the experiment is examined.

A Study on the Characteristics of Moisturizing Cream Containing Sea Cucumber Extract

( Jang Kyungseop ),( Kim Gilyoung ),( Huh Kwangsun ) 한국공업화학회 2021 한국공업화학회 연구논문 초록집 Vol.2021 No.0

Chlorella-gold nanorods hydrogels generating photosynthesis-derived oxygen and mild heat for the treatment of hypoxic breast cancer

Lee, Changkyu,Lim, Kyungseop,Kim, Sung Soo,Thien, Le Xuan,Lee, Eun Seong,Oh, Kyung Taek,Choi, Han-Gon,Youn, Yu Seok Elsevier 2019 Journal of controlled release Vol.294 No.-

<P><B>Abstract</B></P> <P>Hypoxic tumors are rarely cured because their low oxygen environment restricts the cytotoxicity of many chemotherapeutics by blocking the production of intracellular reactive oxygen species. Inspired by the highly efficient production of oxygen as a waste product of chlorella photosynthesis, we developed an <I>in situ</I> rapidly gelling BSA-PEG–based hydrogel depot system that contains chlorella and gold nanorods, namely Chlorella AuNRs BSA-Gel. The entrapped chlorella in our gel efficiently generated a high level of oxygen and oxygenated hemoglobin <I>via</I> photosynthesis in response to 660-nm light <I>in vitro</I> and <I>in vivo</I>, respectively. The incorporated gold nanorods showed excellent performance in precisely increasing the surrounding temperature to 41–42 °C responding to 808-nm near-infrared laser, which presumably played a supporting role in expanding the tumor vasculature and thereby facilitating the delivery of doxorubicin and oxygen to hypoxic tumors of mice. Our results showed that a combined therapy of Chlorella AuNRs BSA-Gel plus Dox followed by irradiation at 660 nm and 808 nm significantly abolished 4 T1 breast cancer cell-xenografted tumors of BALB/C mice. We believe that our oxygen-generating and mild heat-emitting hydrogel should be considered to be a valid prototype of a local depot system for treatment of hypoxic tumors.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

PMSG Wind Turbine Simulation under the consideration of real characteristics

심준보(Sim, Junbo),김명호(Kim, Myungho),박기현(Park, Kihyeon),한경섭(Han, Kyungseop) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11

A various algorism has been studied to extract possibly every energy from a wind turbine in conjunction with the increase of concern about wind power system. In order to verify these control algorism, it is essential to make the most similar conditions to the real wind turbine's environment. Therefore, using separately excited DC motor a wind turbine the most similar to the real turbine is simulated. Tower shadow effect and Wind shear effect are considered as well as inertia emulation. For the control of Back-to-Back Converter Vector current control methods and space vector pulse width modulation are used and for reducing THD of grid current LCL filter is considered. This simulation results verified the energy produced by wind all flows into the utility under the consideration of the characteristics of a wind turbine. The result of this paper is expected to be used as a basic material for analyzing the characteristics of the wind turbine generator.

하이드로폰 스테이브의 충격 특성 해석

조치영(Cheeyoung Joh),김경섭(Kyungseop Kim),서희선(Heeseon Seo),조요한(Yo-Han Cho),홍진숙(Chinsook Hong),노용래(Yongrae Roh) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.10

Small gold nanorods-loaded hybrid albumin nanoparticles with high photothermal efficacy for tumor ablation

Seo, Bohyung,Lim, Kyungseop,Kim, Sung Soo,Oh, Kyung Taek,Lee, Eun Seong,Choi, Han-Gon,Shin, Beom Soo,Youn, Yu Seok Elsevier 2019 Colloids and surfaces Biointerfaces Vol.179 No.-

<P><B>Abstract</B></P> <P>Photothermal therapy using gold nanorods (AuNRs) has gained great attention for cancer therapy because AuNRs emit heat and induce tumor cell death responding to the near infrared light. However, the anticancer efficiency of AuNRs alone is undermined by its poor in vivo stability and potential toxicity. The prime purpose of this study was to send more AuNRs into tumors to more fully ablate them. For this, we fabricated hybrid albumin nanoparticles encapsulating small AuNRs (AuNRs-Alb-NPs), which take advantage of biocompatible albumin as a carrier, with better tumor targetability and high in vivo photothermal activity. The sizes of length/width of AuNRs were approximately 20.5 nm and 4.6 nm, respectively, showing a 4.5 aspect ratio, and the size of the resulting AuNRs-Alb-NPs was ˜130 nm, all of which are favorable for glomerular filtration and passive tumor targeting via extravasation. We chose the best formulation for AuNRs-Alb-NPs by in vitro cytotoxicity based on photothermal conversion efficiency considering the incorporated number of AuNRs. Visualized by a photothermal camera, the local tumor temperature of mice treated with AuNRs-Alb-NPs increased to 57℃, which was sufficient for the hyperthermal effect with 808 nm laser irradiation. Subsequently, AuNRs-Alb-NPs displayed remarkably better tumor ablation vs. naïve formulation of AuNRs (tumor volume: 73.8 ± 105.8 vs. 1455.3 ± 310.4 mm<SUP>3</SUP> at day 8) in the glioblastoma N2a tumor-bearing mice. Most of all, we demonstrated, using photoacoustic imaging and inductively coupled plasma mass spectrometry, that this much better tumor ablation was due to enhanced tumor targeting with albumin nanoparticles. We believe our AuNRs-Alb-NPs should be considered promising photothermal agents that are safer, have good targetability, and exhibit excellent tumor ablation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We developed a prototype of small gold nanorods-loaded albumin nanoparticles. </LI> <LI> The nanoparticles exhibited noticeable cytotoxicity on the glioblastoma N2a cells. </LI> <LI> The nanoparticles were much more potent in killing N2a tumors in vivo versus naïve gold nanorods. </LI> <LI> The hybrid albumin nanoparticles would be a potential photothermal agent for treating brain cancer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

전구음원 신호를 이용한 시간영역 지음향학적 인자 역산

김경섭,박철수,김성일,성우제,Kim Kyungseop,Park Cheolsoo,Kim Seongil,Seong Woojae 한국음향학회 2005 韓國音響學會誌 Vol.24 No.6

본 논문에서는 지난 2004년 동해에서 수행된 MAPLE 04 실험에서 수집된 일련의 전구음원 신호 중 일부를 이용하여 시간 영역에서 지음향 인자 역산을 수행하였다. 이를 위해 수직선배열을 통해 수집된 채널 별 신호 파형과 모의 신호 파형을 직접 비교하는 형태의 목적함수를 구성하였다. 모의 신호는 음선 이론을 사용하여 모델링하였고, 광역최적화 알고리즘인 VFSA (very fast simulated annealing)를 사용하여 목적함수를 최적화하였다 기존의 전달손실비교를 통한 역산 결과(음향학회지 본 호 게재)들과 비교하여 지음향 인자들이 일관성 있게 추정되었음을 확인하였으며, 이 역산 결과를 이용하여 얻은 모의 신호와 계측 신호 간 비교 그림을 제시하였다. In this Paper. a time-domain geoacoustic inversion was performed using the bulb signals measured during MがU. 04 experiment conducted in the East Sea of Korea in 2004. An obiective function was defined as a direct cross-correlation between the measured and the simulated signals in time domain. The ray theory was used to model the wave propagation in time domain and optimizations were Performed using VFSA (very fast simulated annealing) algorithm. Comparison of inversion results with those from transmission loss matching (an accompanying paper in this issue of the Journal of the Acoustical Society of Korea) shows that Parameters are consistently inverted. Direct time series comparisons between the measured signals and the simulated signals are Presented based on inversion results.

전달손실 비교를 통한 지음향학적 인자 역산과 정합장처리

김경섭,박철수,김성일,성우제,Kim Kyungseop,Park Cheolsoo,Kim Seongil,Seong Woojae 한국음향학회 2005 韓國音響學會誌 Vol.24 No.6

본 논문에서는 2004년 동해에서 수행된 MAPLE 실험의 음향계측 자료를 이용한 지음향학적 인자 역산기법을 제시하고 제안된 기법의 검증을 위해 음원의 위치추적 테스트를 수행하였다. 역산을 위한 목적함수는 예인 음원과 고정된 수직선배열로부터 획득된 음향신호를 이용하여 구한 전달손실과 모의된 전달손실과의 상관관계를 평가하도록 정의하였다. 목적함수의 최적화는 광역 최적화 알고리즘인 VFSA (Very Fast Simulated Annealing)를 사용하여 수행하였다. 본 역산기법을 5개의 주파수 토널 성분 데이터에 적용한 후 이를 바탕으로 실험해역의 지음향 모델을 구성하였다. 끝으로 정합장처리를 통해 예인 음원의 위치를 추적하여 역산된 지음향학적 인자들의 타당성을 검토하였다. This paper proposes a geoacoustic inversion method for the experimental data or MAPLE 2004 experiment conducted in the East Sea of Korea in 2004 and shows source tracking test results to validate the Proposed inversion method. An objective function is defined as a correlation function of the measured and the simulated transmission loss data. The measured transmission data were obtained using a multi-tonal towed source and VLA. The VFSA (Very Fast Simulated Annealing) is applied to the inversion Problem which optimizes the objective function. After performing the inversion process for the S frequencies tonal data independently. geoacoustic models are constructed. Finally matched-field source tracking is Performed using the inverted parameters to verify them.