• 한국소음진동공학회논문집
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• 제19권12호
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• pp.1269-1280
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• 2009

This study was performed to construct sound performance DB of royal palace buildings and to examine the special quality more scientifically. Research target of royal palace were Changdeokgung and Gyeongbokgung. Sound insulation performance between the adjacent room and facade, room acoustics of Pyeonjeon and Chimjeon which is representative building in royal palace were examined through field measurement. Measured values of RT($T_{mf}$) at Pyeonjeon were 0.78 sec. and 1.03 sec. in Seonjeongjoen and Sajeongjoen, respectively. The RTs of both Pyeonjeon buildings were estimated suitable for speech and lecture considering their volume. The RT($T_{mf}$)s at Chimjeon were measured in range of 0.29~0.55 sec. This meant that the acoustic energy in rooms was decreased by sound transmission through mulberry paper(Hanji) of traditional windows and doors. As a sound insulation performance, the single-number quantities($D_{ls,2m,nT,w}$) of the building facades in Pyeonjeon and Chimjeon were measured 4~20 dB. Also the single-number quantities($D_{p,w}$) between the adjacent rooms in Chimjeon were measured 3~18 dB. Sound insulation performance of traditional building elements such as window and door depended strongly on their layers and area.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.258-264
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• 2012

The overall aim of this paper is to determine coupling loss factor of welding point between shell and cylinder using loss factor and structural loss factor. For this purpose, two kinds of loss factor were adopted. One is loss factor of each sub structure, another is structural loss factor based on the complex welded or assembled structure. Using these two parameters, it is possible to derive the coupling loss factor which represents characteristic condition of SEA theory. Coupling loss factor of conjunction in complex structure was expressed as power balance equation. The derived equation for a coupling loss factor has been simplified on the assumption of one way (uni-directional) power flow between multi-sub structures. Using these conditions, it is possible to find the equation of coupling loss factor expressed as above two loss factors. To check the effectiveness of above equation, this paper used two-stage application. The first approach was application between simple cylinder and shell. The next was adopted rotary compressor. Rotary compressor has three main conjunctions between shell and internal vibration part. This equation was applied to find out the optimum welding point with respect to reduce the noise propagation. It shows the effective tool to evaluate the coupling loss factor in complex structure.

• KIEAE Journal
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• 제14권3호
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• pp.87-95
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• 2014

The purpose of this study is to evaluate the correlation coefficients between the airtightness and sound insulation performance of Han-style windows in New Han-ok. To achieve these goals, field measurements were accomplished in 18 bedrooms of 16 Han-oks in which actual residents were living, and then lab measurements were proceeded in the reverberation lab for evaluating the sound insulation performance. Followings are results. The results of the correlation analysis between the airtightness(Air change per hour at 50 Pa, ACH50) and sound insulation performance(Sound reduction index, Rw) in bedrooms of actual Han-oks, it was found that there were no significant correlation between two evaluating values. On the other hand, it was analyzed that the correlation coefficients of total 24 structures(double casement windows, single casement window, casement and sliding windows, single sliding window, 6 types per each structure) were located on 0.6757 exponentially and 0.4154 lineary in the lab evaluating conditions. But, The results of evaluating 4 structure classificatorily, it was found that there were high correlation coefficients(0.8665~0.9273 at ACH50, 0.8414~0.9346 at Rw). These results were signified that the correlation coefficients were changed according to the each structure and case by case analysis were necessary at the same time.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.802-807
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• 2003

International Convention Center Jeju(ICCJ) was planed and built for accommodating a variety of conventional and exhibitional activities. For a better flexibility of operation, almost all rooms in ICCJ are designed to be subdivided Into a couple of small rooms with installation of movable partition walls. Architectural and acoustical design should be deliberatively and cooperatively undertaken to cope with such a complex condition. Conference hall, the largest room in ICCJ, has a capacity of 5000 seats who:1 used as a whole. It could be divided into 3 halls, one with 2000 pre-installed seats on slanted floor, up/down removable stage and its settings above, and the other 2 flat rooms with no seats installed. A devided hall with pre-installed seats and stage is designed for a multi-use auditorium. Almost all surfaces except ceilings adjacent to the stage are sound absorptively treated, in regard to extensive use of sound reinforcement systems. Its reverberation time 1.65 sec without audience, which is roughly correspond to 1.50 sec with fully occupied audience. When there is a need for a larger room, all the partition wail Is removed and the hall could be used as a whole. Exhibition hall is located in the first floor of ICCJ. Absorption and softness are needed for the hat 1 because exhibition behavior has something noisy features. Perforated MDF panels with porous materials and air space in the back groundare adopted for the walls. There are one large, two medium, and several small convention rooms in ICJJ. The room are also acoustically designed for maximum flexibility with no defects soundwisely.

• 천문학회보
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• 제41권1호
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• pp.68.2-68.2
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• 2016

We present the variability and time lag measurements of PG 0934+013 based on the photometric and spectroscopic monitoring campaign over two years. We obtained 46 epochs of data from the spectroscopic campaign, which was carried out using the South African Large Telescope with 1 week cadence over two sets of 4 month-long observing period, while we obtained 80 epochs of B band data from the campaign. Due to the six month gap between two campaigns, we separately measured the time lag of the $H{\beta}$ emission line by comparing the emission line light curve with the B band continuum light curve using the cross-correlation function techniques. We determined the time lags and black hole mass.

• 한국전자통신학회논문지
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• 제6권5호
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• pp.703-708
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• 2011

본 논문에서는 대형 교회를 제외한 대부분의 교회가 협소한 공간에 많은 청중을 수용하고자 발코니 층을 설치하여 음의 사각지역 및 음상 정위가 어긋난 지역이 발생하는 문제를 경제적 관점에서 컴퓨터 시뮬레이션을 이용하여 음의 사각지역 및 음상의 개선하는 해결방안을 제시한다. 본 연구에서는 특정교회에 대하여 컴퓨터 시뮬레이션 툴로 경제적으로 쉽게 구할 수 있는 Mapp online으로 사용하였으며, 서브 스피커의 추가 설치 및 메인 스피커 대비 서브 스피커의 -10 dB 이득조절로 명료도를 실측값과 비교한 결과 약 52% 상승하여 명료도가 "보통"에서 "아주 좋음" 단계로 개선됨을 확인할 수 있었다.

• 한국통신학회논문지
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• 제36권6B호
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• pp.689-696
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• 2011

본 논문에서는 PSK(Phase-Shift-Keying) 변조와 PPM(Pulse Position Modulation) 방식의 혼합형이라 볼 수 있는 PSSK(Phase Silence Shift Keying) 변조 방식을 수중 통신에 적용한 결과를 제시한다. 수중 통신 시스템의 성능은 수중 채널 특성에 영향을 많이 받는다. 특히, 잔향 및 다중 경로(Multi-path)로 인한 지연 확산은 데이터 전송 시 인접 심벌간의 간섭 (ISI : Inter Symbol Interference)을 발생시켜 통신의 성능을 저하시킨다. 또한 수중 센서 네트워크인 경우 그 운용 환경의 특수성으로 언해 전력 효율적인 측면도 시스템 구성의 중요한 고려 요소가 된다. PSSK 변조 방식은 2개의 직교 심별을 전송하는 방식으로 한 주기 내에 silence 구조댄 사용함으로써 전력 사용을 절반으로 줄일 수 있다. 이로 인해 변조 심벌간의 거리를 늘려 BER(Bit Error Rate) 성능을 향상 시킬 뿐만 아니라 송신 전력을 낮추어 전력 효율적인 측면의 성능 향상도 기대 할 수 있다. 근거리 해상 실험 결과 QPSK 변조 방식인 경우 BER이 $3.19{\times}10^{-1}$ 이였으며, PSSK 인 경우 BER이 $2.89{\times}10^{-1}$ 이었다.

• 수산해양기술연구
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• 제34권1호
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• pp.52-61
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• 1998

We studied behaviour pattern of anchovy (Engraulis japonicus) shoal by a method of shoal echo integration and tested species identification by a method of artificial neural network using the acoustic data collected in the East China Sea in March 1994 and in the southern coastal waters of the East Sea of Korea in March 1995. Between areas, frequency distribution of 10 shoal descriptors was different, which showed characteristics of shoal behaviour in size, bathymetric position and acoustic strength. The range and mean of shoal size distribution in length and height was wider and bigger in the southern coastal waters of the East Sea than in the East China Sea. Relative shoal size of China Sea. Fractal dimension of shoal was almost same in both areas. Mean volume reverbration index of shoal was 3 dB higher in the southern coastal waters of the East Sea than in the East China Sea. The depth layer of shoal distribution was related to bottom depth in the southern coastal waters of the East Sea, while it was between near surface and central layer in the East China Sea. Principal component analysis of shoal descriptors showed the correlation between shoal size and acoustic strength which was higher in the southern coastal waters of the East Sea, than in the East China Sea. Correlation was also found among the bathymetric positions of shoal to some degree higher in the southern coastal waters of the East Sea than in the East China Sea. The anchovy shoal of two areas was identified by artificial neural network. The contribution factor index (Cio) of the shoal descriptors between two areas were almost identical feature. The shoal volume reverberation index (Rv) was showed the highest contribution to the species identification, while shoal length and shoal height showed relatively high negative contribution to the species identification.

• 천문학회지
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• 제52권4호
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• pp.109-119
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• 2019

While the reverberation mapping technique is the best available method for measuring black hole mass in active galactic nuclei (AGNs) beyond the local volume, this method has been mainly applied to relatively low-to-moderate luminosity AGNs at low redshift. We present the strategy of the Seoul National University AGN Monitoring Project, which aims at measuring the time delay of the $H{\beta}$ line emission with respect to AGN continuum, using a sample of relatively high luminosity AGNs out to redshift z ~ 0.5. We present simulated cross correlation results based on a number of mock light curves, in order to optimally determine monitoring duration and cadence. We describe our campaign strategy based on the simulation results and the availability of observing facilities. We present the sample selection, and the properties of the selected 100 AGNs, including the optical luminosity, expected time lag, black hole mass, and Eddington ratio.

• 해양환경안전학회지
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• 제23권7호
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• pp.948-955
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• 2017

현재 해양플랜트용 패널의 주요한 중심재는 다공성재료(미네랄울) 이지만, 뛰어난 차음성능에도 불구하고 환경적인 이유로 이를 대체할 재료가 요구되고 있다. 허니컴 구조는 무게 대비 강도가 우수하여 산업전반에서 많이 쓰이고 있다. 하지만 소음진동 측면에서의 연구는 미미하다. 다공성재료를 대체하기 위한 연구로서 허니컴의 음향학적 연구가 필요하다. 본 논문에서는 허니컴패널을 대칭모드와 비대칭모드의 중첩으로 가정하여 수치해석을 진행하였다. 이러한 이론을 통한 수치해석과 실험결과를 비교하여 수치해석의 신뢰성을 검증하였다. 그리고 수치해석을 통해 허니컴패널의 차음특성을 연구하고 중심재로서의 가능성을 평가하였다. 패널두께를 키울수록 일치주파수가 저주파수로 이동하였다. 셀사이즈와 셀벽의 사이각이 감소함에 따라 차음성능이 개선되었고, 셀벽두께의 경우 증가할수록 차음성능이 향상되었다.