http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : 崔康薰(Kang-Hoon Choi) (검색결과 18 건)
- 무료
- 기관 내 무료
- 유료
-
거제 내만해역에서의 고주파 양상태 해수면 음파산란 채널 측정 및 모의
최강훈,김용빈,김시문,최지웅,Choi, Kang-Hoon,Kim, Yongbin,Kim, Sea-Moon,Choi, Jee Woong 한국음향학회 2021 韓國音響學會誌 Vol.40 No.1
High-frequency bistatic sea surface scattering channels according to sea state were measured at an experimental site of Geoje bay in April 2020, and compared with predictions based on scattering theory. A linear frequency-modulated signal with a center frequency of 128 kHz and a bandwidth of 32 kHz was used for the acoustic measurements. Sea surface wavenumber spectrum was calculated from surface roughness data measured by a wave buoy, and bistatic scattering cross-section of Small Slope Approximation (SSA) based on the wavenumber spectrum was estimated. In addition, scattering from near-surface bubbles using wind speed measured during experiments was considered. Surface scattering channel intensity impulse responses were simulated using the scattering cross-section and the simulation results were compared and analyzed with the field data.
-
최강훈,황인성,이상국,최지웅,Choi, Kang-Hoon,Hwang, In-Seong,Lee, Sangkug,Choi, Jee Woong 한국음향학회 2022 韓國音響學會誌 Vol.41 No.2
Underwater acoustic wave in shallow water is propagated through multipath that has a large delay spread causing Inter-Symbol Interference (ISI) and these characteristics deteriorate the performance in the communication system. In order to analyze the communication performance and investigate the correlation with multipath delay spread in a reverberant environment, an underwater acoustic communication experiment using Binary Phase-Shift Keying (BPSK) signals with symbol rates from 100 sym/s to 8000 sym/s was conducted in a 5 × 5 × 5 m<sup>3</sup> water tank. The acoustic channels in a well-controlled tank environment had the characteristics of dense multipath delay spread due to multiple reflections from the interfaces and walls within the tank and showed the maximum excess delay of 40 ms or less, and the Root Mean Squared (RMS) delay spread of 8 ms or less. In this paper, the performances of Bit Error Rate (BER) and output Signal-to-Noise Ratio (SNR) were analyzed using four types of communication demodulation techniques. And the parameter, Symbol interval to Delay spread Ratio in reverberant environment (SDR<sub>rev</sub>), which is the ratio of symbol interval to RMS delay spread in the reverberant environment is defined. Finally, the SDR<sub>rev</sub> was compared to the BER and the output SNR. The results present the reference symbol rate in which high communication performance can be guaranteed.
-
최강훈,정혜인,안병관,Choi, Kang-Hoon,Jung, Hye-In,An, Byeong-Kwan 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.11
Rhodamine B (RhB) was utilized as a dye sensitizer for dye-sensitized solar cells (DSSCs) and its photovoltaic property was examined under the illumination of AM 1.5 G, $100mWcm^{-2}$. DSSCs based on RhB exhibited typical photovoltaic properties with an open-circuit voltage ($V_{OC}$) of 0.34 V, a short-circuit current ($J_{SC}$) of $1.55mA{\cdot}cm^{-2}$, a fill factor (FF) of 50%, and a conversion efficiency (PCE) of 0.26%. In order to further improve the photovoltaic properties of RhB-based DSSCs, the effect of (i) incorporating a strong electron-donating NCS unit into the RhB molecular backbone, (ii) combining a bis-negatively charged zinc complex anion ($Zn-dmit_2$, dmit=di-mercapto-dithiol-thione) with the amine cation of RhB, (iii) co-adsorbing RhB dyes with chenodeoxycholic acid (CDCA) molecules onto porous $TiO_2$ electrodes, was investigated and discussed.
-
최강훈,윤영글,김선효,김현수,최지웅,배호석,박경주,Choi, Kang-Hoon,Yoon, Young Geul,Kim, Sunhyo,Kim, Hyeonsu,Choi, Jee Woong,Bae, Ho Seuk,Park, Kyeongju 한국음향학회 2019 韓國音響學會誌 Vol.38 No.1
The Indo-Pacific bottlenose dolphins (Tursiops aduncus) are a toothed whale using echolocation clicks and have been studied continuously abroad. However, most studies on this whale's clicks were performed about captive animals and, in Korea, only the studies of the whistle sounds of this animal were done. In this paper, acoustic characteristics of clicks were analyzed about the free-ranging Indo-Pacific bottlenose dolphins living in the coast of the Jeju Island. Acoustic parameters such as signal duration, 1st and 2nd peak frequency, 3 dB and 10 dB bandwidth for acoustic characteristics were calculated and compared with those of Australian species. As a result, the signal durations had average of $38{\mu}s$ and most clicks were within range of $20{\mu}s-60{\mu}s$. The two types of bandwidths showed both narrowband and broadband characteristics, and bimodal signal characteristics were confirmed through the 1st peak frequencies(average of $96kHz{\pm}18kHz$) and the 2nd peak frequencies(average of $69kHz{\pm}19kHz$). 남방큰돌고래(Tursiops aduncus)는 클릭음을 사용하는 이빨고래로써 국외에서 지속적인 연구가 수행되어 왔다. 그러나 남방큰돌고래의 클릭음에 대한 연구는 대부분 사육중인 개체에 대해 이루어졌으며 국내에서는 휘슬음에 관한 연구만 수행되었다. 본 논문에서는 제주 연안에 서식하는 야생개체의 남방큰돌고래 클릭음에 대한 음향특성을 분석하였다. 음향특성을 분석하기 위해 음향 파라미터인 신호 길이, 첫 번째 피크 주파수, 두 번째 피크 주파수, 3 dB 대역폭 및 10 dB 대역폭을 산출하였으며 호주 서식 종의 클릭음 음향특성과 비교하였다. 결과적으로, 신호 길이는 평균 $38{\mu}s$를 나타냈고 대부분의 클릭음이 $20{\mu}s-60{\mu}s$ 범위 내에 속하였다. 2종류의 대역폭의 경우 협대역과 광대역의 주파수 특성 모두 나타냈으며, 첫 번째 피크 주파수(평균 $96kHz{\pm}18kHz$)와 두 번째 피크 주파수(평균 $69kHz{\pm}19kHz$)를 통해 바이모달 신호 특성을 확인하였다.
-
음향채널이 존재하는 천해에서의 수동 시역전 통신 성능 분석
최강훈,김선효,최지웅,김현수,김병남,Choi, Kang-Hoon,Kim, Sunhyo,Choi, Jee Woong,Kim, Hyeonsu,Kim, Byoung-Nam 한국음향학회 2018 韓國音響學會誌 Vol.37 No.1
수동 시역전 기법은 시공간적인 집속효과를 통해 다중경로 채널응답에 의한 인접 심볼간 간섭의 영향을 줄임으로써 수중통신 시스템의 오류 성능을 향상시킬 수 있는 방법이다. 이러한 수동 시역전 기법은 일반적으로 시역전 결합에 사용되는 수신신호가 많을수록 큰 공간 다이버시티 이득을 얻기 때문에 많은 수의 수신기를 사용할 때 우수한 통신 성능을 얻을 수 있다. 본 논문에서는 제한된 개수의 수신기를 사용하더라도 많은 수의 수신기를 사용할 때와 근접한 통신 성능을 얻을 수 있는 수신기의 개수와 조합에 대해 분석한다. 분석을 위해 2015년 5월에 제주 남서쪽 해역에서 수행된 SAVEX15(Shallow-water Acoustic Variability Experiment 2015) 실험 데이터를 활용한다. 음향채널이 존재하는 채널 특성 때문에 에너지가 집중되는 수심이 존재하였고 에너지가 집중되는 수심에 존재하는 수신기를 포함하여 수동 시역전 결합을 할 때, 일부의 수신기만을 사용하여 최적에 가까운 통신 성능을 도출할 수 있음을 보인다. A passive time-reversal technique can improve error performance of the underwater communication system by reducing influence of inter-symbol interferences, which is caused by a multipath channel response. The passive time-reversal communication system equipped with numerous receivers generally can obtain superior error performance since larger diversity gain can be obtained as the number of available received signal increased. In this paper, we analyze the optimal number and combination of receivers that can approximately achieve the best error performance when using the limited number of receivers. For this analysis, we use communication data collected during SAVEX15 (Shallow-water Acoustic Variability Experiment 2015) carried out in the south-western part of Jeju Island from May 14 to May 28, 2015. Analysis results show that there are depths of energy concentration due to the channel characteristics in which the underwater sound channel are present, and the passive time-reversal technique using the limited number of the receivers can derive near-optimal communication performance if the receivers for time-reversal processing are located at the depths where energy is concentrated.
-
탈지미세조류로부터 폴리페놀 생산 증대를 위한 열수추출 조건 최적화
최강훈 ( Kang Hoon Choi ),이지현 ( Ji Hyun Lee ),조재민 ( Jae Min Jo ),신슬기 ( Seul Gi Shin ),김진우 ( Jin Woo Kim ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.3
합성 항산화제에 대한 대체제로 천연 항산화제에 대한 연구가 활발히 진행되고 있으며 미세조류는 천연 항산화제의 원료로 많은 관심을 받고 있다. 본 연구에서는 탈지미세조류에서 총 폴리페놀(TPC) 추출증대를 위해 추출용매, 온도, 시간, 고액비율과 에탄올 첨가 농도 최적화를 수행하였다. 열수와 유기용매 추출성능을 비교했을 때, 열수추출이 유기용매 보다 우수한 성능을 보였으며 온도 증가에 따라 추출성능도 비례하여 증가함을 보였다. 열수에 의한 추출이 에탄올용액 추출(>98%)에 비해 우수한 성능을 보였으며40% 에탄올 용액을 이용한 열수 추출이 가장 우수한 추출 효과를 보였다. 추출조건10 min, 100 ºC, 40% 에탄올 열수추출에서 최대 폴리페놀 농도인 3.35 mg GAE (gallic acid equivalent)/gDM을 얻을 수 있었다. 지질 추출을 위한 유기용매 전처리 공정이 선수행 되었음에도 불구하고 탈지미세조류(TetraselmisKCTC 12236BP)의 폴리페놀 농도가 다른 탈지이전 미세조류와 동등한 수준임을 확인할 수 있어 탈지미세조류가 천연 폴리페놀의 원료로서 적합함을 확인 할 수 있었다. 또한, 고액추출을 모사하기 위해 Peleg 모델을 이용해 예측한 폴리페놀 농도가 실험에 의해 얻어진 값과 높은 일치도를 보임으로 모델을 이용한 모사가 폴리페놀 추출 모사에 유용함을 증명할 수 있었다. The search for natural antioxidants as alternatives to synthetic products is growing. Microalgae have emerged as a source of natural antioxidants with significant and diverse health-promoting properties. In this study, the effects of hot-water extraction conditions on total polyphenol compounds (TPC) production were investigated for lipid extracted microalgae (LEA). In order to enhance the polyphenol productivity, the extraction variables including solvents, temperature, time and ethanol concentration were optimized. The results showed hot-water extraction provided a higher extraction efficiency than the organic solvents and extraction at high temperatures showed a better extraction efficiency. While hot-water extract showed a higher extraction efficiency compared to 98% ethanol extraction, the mixture of water and ethanol (40:60 v/v) showed the highest production of polyphenols. The maximum polyphenols of 3.35 mg GAE (gallic acid equivalent)/g DM were obtained at the optimized extraction time of 10 min, 100 ºC and 40% ethanol, respectively. Although Tetraselmis KCTC 12236BP was preprocessed by hexane to remove lipid for bio-diesel production, the results showed LEA contains relatively high level of polyphenols compared to untreated microalgae which can be used in the production of value-added materials. The predictions obtained from the developed Peleg``s model were compared with the experimental data under the same operating conditions. The predicted and experimental data were consistent, indicating the reliability of the model.
-
-
-
-
KISS연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
