• 한국산업보건학회지
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• 제32권2호
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• pp.137-145
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• 2022

Objectives: This study aimed to identify PM₁₀ mass concentration levels and conduct peak identification during five tasks in agricultural works. Methods: We investigated five agricultural tasks in 12 farms, which were harvesting, plowing, sowing, planting, and decapitation. All samples were measured by using the portable aerosol spectrometer(PAS 1.108) and the aerosol monitor(SidePak AM520). The collected data were compared with the national PM₁₀ concentrations. They were calculated to descriptive statistics, independent t-test, or ANOVA, and the peak identification on time series graph. Results: The ten investigated farms showed no significant difference with the national PM₁₀ concentrations, but the two greenhouses(AM, 143.31, 85.16 ㎍/m³) showed significant difference(p<0.05). As a result of the peak identification, the harvesting tasks showed repeated peak occurrence with the background concentration level of about 50 ㎍/m³. For plowing and sowing tasks, the peak occurred intermittently when the working was conducted near the sampling sites. Among the five tasks, the arithmetic mean of the harvesting task was 138.84±294.71 ㎍/m³, which was significantly higher than the other tasks(p<0.05). In addition, the case of using a tractor was higher than the case of not using the tractor(p<0.05), and the driver's seat showed the highest concentration(AM, 95.81 ㎍/m³). Conclusions: Works in greenhouses might have exposure to PM₁₀, while outdoor works is similar to general atmospheric PM₁₀ concentration levels. However, there is a possibility of intermittent exposure to high concentrations of PM₁₀ depending on the characteristics of agricultural tasks.

• 대한토목학회논문집
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• 제8권1호
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• pp.97-102
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• 1988

한반도(韓半島)에서 역사지진(歷史地震)과 계기지진(計器地震) 기록(記錄)에 의한 변형(變形)에너지 방출량(放出量)이 산정되었다. 또한, 지진발생진도(地震發生震度)와 누적빈도(累積頻度)의 관계를 산출하였다. 본(本) 연구(硏究)의 주(主)된 목적으로서 한반도(韓半島)의 지진위험도(地震危險圖)를 작성하였다. 그리하여 지진위험도(地震危險圖)의 각 구역(區域)에서 두 종류 구조물(構造物)의 내진설계(耐震設計)를 위한 최대지반가속도(最大地盤加速度)를 결정하였다. 첫번째 형태는 건물이나 교량과 같은 일반(一般) 구조물(構造物)이고 두번째 형태는 원자력발전소(原子力發電所)와 같은 특수구조물(特殊構造物)이다.

• 한국세라믹학회지
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• 제34권4호
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• pp.436-442
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• 1997

The bimodal distribution of CuCl nano-crystals precipitated in alumino-borosilicate glass matrix (30SiO2-45B2O3-7.5Al2O3-7.5Na2O-7.5CaO-2.5GeO2(mole %)) was investigated by TEM and the temperature dependent optical spectroscopy. Two types of CuCl particles with different size were observed by TEM and it was confirmed by the splitting of Z3 absorption peak at low temperature and the occurrence of deflection point in the optical spectra with temperature.

• Earthquakes and Structures
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• 제4권3호
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• pp.325-339
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• 2013

A number of structural and modal parameters are derived from the strong motion records of an instrumented G + 9 storeyed RC building during Bhuj earthquake, 26 Jan. 2001 in India. Some of the extracted parameters are peak floor accelerations, storey drift and modal characteristics. Modal parameters of the building are also compared with the values obtained from ambient vibration survey of the instrumented building after the occurrence of earthquake. These parameters are further used for calibrating the accuracy of fixed-base Finite Element (FE) models considering structural and non-structural elements. Some conclusions are drawn based on theoretical and experimental results obtained from strong motion records and time history analysis of FE models. An important outcome of the study is that strong motion peak acceleration profile in two horizontal directions is close to FE model in which masonry infill walls are modeled.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.654-657
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• 1995

A series of excitation spectra (7Fo→5Do transition) of Eu(Ⅲ) ion in aqueous solution ([Eu(Ⅲ)]=1.12 × 10-2 mol L-1; pH 1.0 to 7.0) were obtained under CO2 free atmosphere using a pulsed tunable dye laser system. The broad and low intensity spectra (peak maximum: 578.89 nm) showed that the trivalent ion (Eu3+) underwent a low degree of hydrolysis at pH below 6.0. Eu(Ⅲ) hydroxo complex formation seemed more significant at pH above 6.0, shown by the occurrence of intense new peak at 578.63 nm. The spectra of those solutions prepared in N2 atmosphere showed no signs of the presence of interfering carbonate species. The Eu(Ⅲ) hydroxo complex formation was not observed when complexation studies between Eu(Ⅲ) ion and weak organic acids (e.g. glutarate and diglycolate) were conducted at pH 6.0 or below.

• 대한임베디드공학회논문지
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• 제14권3호
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• pp.123-131
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• 2019

In recent years, a non-contact respiration and heart rates monitoring via IR-UWB radar has been paid much attention to in various applications - patient monitoring, occupancy detection, survivor exploring in disaster area, etc. In this paper, we address a novel approach of real time heart rate estimation using IR-UWB radar. We apply sine fitting and peak detection method for estimating respiration rate and heart rate, respectively. We also deploy two techniques to mitigate the error caused by wrong estimation of respiration rate: a moving average filter and finding the frequency of the highest occurrence. Experimental results show that the algorithm can estimate heart rate in real time when respiration rate is presumed to be estimated accurately.

• 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.

• 한국수자원학회논문집
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• 제33권6호
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• pp.701-709
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• 2000

통합저류함수모형을 IHP 대표유역인 위천과 보청천유역 그리고 대유역인 남한강유역과 낙동강유역의 강우-유출사상에 적용하여 모형의 타당성을 검토하였다. 제안된 모형에 의한 예측 결과와 관측치를 비교해 볼 때 전체적인 수문곡선의 재현성 및 첨두홍수량의 예측에 있어서 상당히 우수한 결과를 나타내었다. 그러나 첨두홍수 발생시간에서는 퍼지제어의 효과로 인해 다소 오차가 발생하였다. 또한 상류단 유입량이 잔유역 유입량에 비하여 상당히 큰 경우에는 충분한 예보선행시간을 확보하기 어려운 문제점이 나타났다.

• Structural Monitoring and Maintenance
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• 제9권2호
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• pp.201-220
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• 2022

Lateral vibrations of footbridges may induce synchronization between pedestrians and structure itself, resulting in amplification of such vibrations, a phenomenon identified by lock-in. However, investigations about accelerations and frequencies of the structural movement that are related to the occurrence of synchronization are still incipient. The aim of this paper is to investigate conditions that could lead to avoidance of synchronization among pedestrians themselves and footbridge, expressed in terms of peak acceleration. The focus is on the low acceleration range, employed in some guidelines as a criterion to avoid synchronization. An experimental campaign was carried out, employing a prototype footbridge that was set into oscillatory motion through a pneumatic exciter controlled by a fuzzy system, with controlled frequency and amplitude. Test subjects were then asked to cross the oscillating structure, and accelerations were simultaneously recorded at the structure and at the subject's waist. Pattern and phase differences between these signals were analysed. The results showed that test subjects tended to keep their walking patterns without synchronization induced by the vibration of the structure, for structural peak acceleration values up to 0.18 m/s², when frequencies of oscillation were around 0.8 to 0.9 Hz. On the other hand, for frequencies of oscillation below 0.7 Hz, structural peak accelerations up to 0.30 m/s² did not induce synchronization.

• 대한교통학회지
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• 제13권4호
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• pp.117-132
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• 1995

Peak-period congestion is a frequent occurrence on many freeways. Entrance-metering is an effective strategey in improving urban freeway traffic condition. This paper describes the prodecure to develop a computer program for proparing optimum ramp-metering stategies. Four existing ramp-metering optimaization models wer reviewed and evaluated in regared to their theories and actural performances. A optimization model was proposed in this paper. Final model takes aform of quadratic programming. The performance of the propeosed model wastest using FREFLO.