• Wind and Structures
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• 제15권5호
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• pp.423-439
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• 2012

Three common medium- rise building forms were physically tested to study their overall wind induced structural response. Emphasis was placed on the torsional response and its correlation with other peak responses. A higher correlation was found between the peak responses than between the general fluctuating parts of the signals. This suggests a common mechanism causing the peak event, and that this mechanism is potentially different to the mechanism causing the general load fluctuations. The measurements show that about 80% of the peak overall torsion occur simultaneously with the peak overall along wind drag for some generic building shapes. However, the peak torsional response occurs simultaneously with only 30%-40% of the peak overall drag for the rectangular model. These results emphasise the importance of load combinations for building design, which are often neglected in the design of medium sized rigid buildings for which the along-wind drag is dominant. Current design wind loading standards from around the world were evaluated against the results to establish their adequacy for building design incorporating wind-induced torsion effects. Although torsion is frequently neglected, for some structural systems it may become more important.

• 한국환경과학회지
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• 제11권10호
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• pp.1081-1087
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• 2002

This study was performed to research the characteristics of suspended particulate for Yellow Sand of January, 1999 in Busan. Yellow Sand frequency during 13 years(1988~2000) in Busan showed maximum in April(57%), next to March(21%), May(16%). According to result of 850hPa weather map and backward isentropic trajectory, this event originated from the Gobi Desert and the Loess Plateau of China. And three mode was found in time series of TSP and PM10 concentration, primary peak showed the maximum hourly concentration at ali station. Gamjeondong as industrial site showed the highest TSP concentration and also had the longest high concentration($geq700\mu\textrm{g}/m^3$). In PM10, concentration of primary peak showed maximum value at Yeonsandong, maximum concentration of secondary and third peak was Deokcheondong. Lasted time from primary peak to secondary peak was about 30 hours, between secondary peak and third peak was 18 hours in Busan, The traveling time between occurrence of Yellow Sand the finding of it was 8~9 hours in Busan and 4~5 hours in central area.

• 전력전자학회논문지
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• 제14권5호
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• pp.415-422
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• 2009

본 논문은 기존의 시스템에 비해 시스템의 전력회로 구조의 큰 변경 없이 밧데리와 같은 전력저장 장치 디바이스의 추가와 개선된 운용방법을 적용한 첨두부하 삭감효과를 갖는 계통연계형 태양광발전시스템(UIPV)을 제안하였다. 개선된 운용방법과 에너지 저장장치의 추가로 기존 시스템에 비해 PV-array 용량을 작게 설치하여도 첨두부하 삭감효과를 크게 할 수 있으며, 가격 및 설치공간 등의 면에서 평가하여 기존시스템보다 더 나아짐을 확인하였다.

• 대한음성학회지:말소리
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• 제60호
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• pp.67-84
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• 2006

The purpose of this study is to find some acoustic parameters on frequency domain to distinguish the Korean nasals, $/m,\;n,\;{\eta}/$ from each other. The new parameters are devised on the basis of LTAS (Long Term Average Spectrum). The maximum peak amplitude and the relevant formant frequency are measured in low and high frequency range, respectively. The frequency of spectral valley and its energy level are also obtained in the specific frequency range of the spectrum. Spectral slope, total energy value in specific frequency range, statistical distribution of spectral energy like centroid, skewness, and kurtosis are suggested as new parameters as well. The parameters that show statistically significant differences across nasals are summerized as follows. 1) in syllable initial positions: the total energy value from 1,500 to 2,200 Hz(zeroENG); 2) in syllable final positions: the peak amplitude of the first formant(peak1_a), the formant frequency with maximum peak amplitude from 4,000 to 8,000 Hz(peak2_f), the maximum peak amplitude of the formant frequency from 4,000 to 8,000 Hz(peak2_a), and the total energy value from 1,500 to 2,200 Hz(zeroENG).

• Structural Engineering and Mechanics
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• 제74권3호
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• pp.407-423
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• 2020

The pre-peak cyclic shear mechanism of two-order asperity degradation of rock joints in the direct shear tests with static constant normal loads (CNL) are investigated using experimental and numerical methods. The laboratory testing rock specimens contains the idealized and regular two-order triangular-shaped asperities, which represent the specific geometrical conditions of natural and irregular waviness and unevenness of rock joint surfaces, in the pre-peak cyclic shear tests. Three different shear failure patterns of two-order triangular-shaped rock joints can be found in the experiments at constant horizontal shear velocity and various static constant normal loads in the direct and pre-peak cyclic shear tests. The discrete element method is adopted to simulate the pre-peak shear failure behaviors of rock joints with two-order triangular-shaped asperities. The rock joint interfaces are simulated using a modified smooth joint model, where microscopic scale slip surfaces are applied at contacts between discrete particles in the upper and lower rock blocks. Comparing the discrete numerical results with the experimental results, the microscopic bond particle model parameters are calibrated. Effects of cyclic shear loading amplitude, static constant normal loads and initial waviness asperity angles on the pre-peak cyclic shear failure behaviors of triangular-shaped rock joints are also numerically investigated.

• 한국의학물리학회지:의학물리
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• 제5권2호
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• pp.13-20
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• 1994

본 연구에서는 감마선 조사, 전자선 조사방법에 의한 전자만의 주업 및 이온 주업 후 전자선조사 방법으로 전자들이 주입된 $\alpha$-$Al_2O_3$의 열자극 발광(Thermoluminescence : TL)에 관련된 결함 형태를 조사하였다. 감마선 조사된 $\alpha$-$Al_2O_3$의 열자극 발광 곡선은 380K, 415K, 440K, 460K 및 475K에서 TL peak가 나타났다. 광흡수 스펙트럼과 자외선 photobleaching 결과로부터 감마선 조사된 $\alpha$-$Al_2O_3$의 380K와 475K TL peak는 F center에, 415K TL peak는 $F^{+}$ center에 기인함을 알았다. 전자선 조사방법에 의하여 전자 주입된 $\alpha$-$Al_2O_3$의 열자극 발광 곡선은 380K, 415K, 440K 및 460K TL peak를 가졌고, $Li^{+}$ 이온 주입 후 전자선 조사방법으로 전자들이 주입된 $\alpha$-$Al_2O_3$는 440K에서 TL peak가 나타났다. 전자선 조사방법에 의한 전자만의 주입과 $Li^{+}$ 이온 주입 후 전자선 조사방법으로 전자들이 주입된 $\alpha$-$Al_2O_3$의 열자극 발광 특성은 380K TL peak는 F center에, 440K TL peak는 $F^{+}$ center에 기인함을 보였다.

• 한국환경생태학회지
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• 제28권4호
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• pp.484-489
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• 2014

본 연구에서는 국립공원 탐방 성수기와 비수기에 따른 빛공해 특성 차이 분석을 목적으로 하였다. 우리나라 21개 국립공원 중 북한산과 무등산국립공원을 제외한 19개 국립공원의 빛공해는 2012년 10월(성수기)과 2013년 1월(비수기)에 촬영된 VIIRS(Visible Infrared Imaging Radiometer Suite) 센서의 DNB(Day and Night Band) 영상 중 구름과 달빛이 없는 시기에 촬영된 영상을 이용하여 추정하였고, bootstrapping 회귀 분석을 이용하여 각 시기별로 어떠한 사회경제적, 정책적 요인이 국립공원 빛공해 수준에 영향을 미치는지 분석하였다. 국립공원 빛공해 특성은 탐방 성수기와 비수기에 따라 다르게 나타났다. 탐방 성수기에는 국립공원 내부의 야간 조명보다 공원 인근 조명이 국립공원 내부의 빛공해 수준에 더 큰 영향을 주었고 비수기에는 공원 인근보다 공원 내부에 의한 영향이 더 큰 것으로 분석되었다. 탐방 성수기에 국립공원 인근 야간 조명 영향이 더 크게 나타난 원인은 공원 인근의 숙박 및 레크리에이션 시설의 야간 조명이 대기 중에서 산란되어 국립공원 내부로 침입하는 스카이글로우현상(sky glow effect)으로 판단된다. 이 결과는 국립공원 빛공해의 피해를 줄이기 위해서는 국립공원 내부 뿐 아니라 특별히 탐방 성수기 동안 인근 지역의 야간 조명을 규제하여야 한다는 것을 시사해준다.

• 한국화재소방학회논문지
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• 제30권4호
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• pp.65-72
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• 2016

이 연구는 비스-(디메틸아미노메틸) 포스핀산(DMDAP), 비스-(디에틸아미노메틸) 포스핀산(DEDAP) 과 비스-(디부틸아미노메틸) 포스핀산(DBDAP)으로 처리된 리기다소나무의 연소 독성 가스의 생성에 관하여 조사하였다. 리기다소나무는 15 wt.% 방염제 수용액으로 3번 붓칠 한 후 상온에서 건조하였다. 연소 독성 기체의 생성물은 콘칼로리미터(ISO 5660-1)를 사용하여 조사하였다. 화학 첨가제로 처리된 첫 번째 피크 질량손실속도($1^{st}-TMLR_{peak}$) 시간은 처리하지 않은 시편과 비교하여 5.9%와 41.2% 범위에서 감소되었다. 두 번째 피크 질량손실속도($2^{nd}-TMLR_{peak}$) 시간은 DMDAP에 대해서 1.8%, DBDAP에 대해서 5.3% 감소하였고 DEDAP에 대하여 1.8% 증가하였다. 피크 일산화탄소 생성농도($CO_{peak}$)는 처리되지 않은 시편보다 1.5~2.0배 더 높았다. 피크 이산화탄소 생성 농도($CO_{2peak}$)는 처리되지 않은 시편과 비교하여 DMDAP에 대해 0.01배 감소되었고 DEDAP에 대해 1.15배, DBDAP에 대해 1.19배 증가하였다. 특히 산소농도는 사람에게 치명적인 15%보다 매우 높게 측정되었다. 전반적으로 가연성 기체의 연소 독성은 처리하지 않은 시편과 비교하여 화학 첨가제에 의해 부분적으로 증가하였다.

• 한국산업보건학회지
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• 제22권3호
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• pp.257-264
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• 2012

Objectives: This study's aims were to evaluate the effects of load center of gravity within an object lifted and feet placements on peak EMG amplitude acting on bilateral low back muscle groups, and to suggest adequate foot strategies with an aim to reducing low back pain incidence while lifting asymmetric load. Methods: The hypotheses that asymmetric load imposes more peak EMG amplitude on low back muscles contralateral to load center of gravity than symmetric load and maximum peak EMG amplitude out of bilateral ones can be relieved by locating one foot close to load center of gravity in front of the other were established based on biomechanics including safety margin model and previous researches. 11 male subjects were required to lift symmetrically a 15.8kg object during 2sec according to each conditions; symmetric load-parallel feet (SP), asymmetric load-parallel feet (AP), asymmetric load-one foot contralateral to load center of gravity in front of the other (AL), and asymmetric load-one foot ipsilateral to load center of gravity in front of the other (AR). Bilateral longissimus, iliocostalis, and multifidus on right and left low back area were selected as target muscles, and asymmetric load had load center of gravity 10cm deviated to the right from the center in the frontal plane. Results: Greater peak EMG amplitude in left muscle group than in right one was observed due to the effect of load center of gravity, and mean peak EMG amplitudes on both sides was not affected by load center of gravity because of EMG balancing effect. However, the difference of peak EMG amplitudes between both sides was significantly affected by it. Maximum peak EMG amplitude out of both sides and the difference of peak EMG amplitude between both sides could be reduced with keeping one foot ipsilateral to load center of gravity in front of the other while lifting asymmetric load. Conclusions: It was likely that asymmetric load lead to the elevated incidence of low back pain in comparison with symmetric load based on maximum peak EMG amplitude occurrence and greater imbalanced peak EMG amplitude between both sides. Changing feet positions according to the location of load center of gravity was suggested as one intervention able to reduce the low back pain incidence.

• Journal of Medicine and Life Science
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• 제19권2호
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• pp.57-65
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• 2022

This study aimed to compare the Korean Activity Status Index (KASI) with the cardiopulmonary exercise test (CPET) among patients with acute myocardial infarction. A total of 2,268 patients (85.4% male; mean age, 59.3±10.2 years; range, 23-90 years) diagnosed with acute myocardial infarction were enrolled in the Regional Center Myocardial Infarction Registry between July 2016 and June 2019. The KASI is a tool used to measure functional capacity by asking patients about their ability to perform specific activities and then scoring their responses. In contrast, CPET is the gold standard for assessing the objective functional capacity in patients undergoing cardiac rehabilitation. Peak oxygen uptake (VO_2peak) was used to analyze the correlation. Patients who completed two consecutive KASI and CPET evaluations during their first (KASI_1, VO_2peak_1) and second visits (KASI_2, VO_2peak_2) for cardiac rehabilitation were included in the study. The mean KASI_1 and KASI_2 scores were 43.3±14.3 and 49.8±13.9, respectively, and the mean VO_2peak_1 and VO_2peak_2 scores were 25.9±8.0 and 28.5±8.3, respectively. Both the KASI scores were significantly correlated with the measured VO_2peak during each visit, with correlation coefficients of 0.385 (P<0.001) and 0.346 (P<0.001), respectively. Moreover, the KASI score and VO_2peak had a linear relationship (VO_2peak_1=0.22×KASI_1+16.5, P<0.001; VO_2peak_2=0.21×KASI_2+18.2,VO_2peak_2=0.21×KASI_2+18.2, P<0.001). This study revealed that the KASI is a valid measure for the follow-up evaluation of the functional capacity of patients. These findings suggest that VO_2peak can be predicted using the KASI score in patients who do not undergo CPET.