• 한국음향학회지
• /
• 제25권2호
• /
• pp.49-55
• /
• 2006

현행 중량 바닥충격음 표준 측정방식인 KS F 2810-2에 의하면 중앙점을 포함한 3-5곳의 타격위치에 대하여 수음실에서 4곳 이상의 지점의 피크레벨을 측정하도록 되어있다. 그러나 이 표준 방식에 의한 동일 상황에서의 측정 결과가 측정기관, 측정횟수, 측정점의 위치 등에 따라 일관성을 보이지 못하고 있음이 종종 발견된다. 이러한 편차는 반복성이나 재현성의 측면에서 측정값의 신뢰도에 영향을 미칠 수 있는 수준으로 우려된다. 측정결과 실험실의 경우 중앙 타격시 63Hz 대역에서 각 지점간의 차이가 l0dB이상 차이를 보였으며, 전체적으로 중간주파수 대역에서 보다 저주파수 대역에서의 편차가 크게 발생하는 것으로 나타났다. 이러한 편차는 저주파수 대역에서의 모드 중첩현상에 의한 것으로 보인다. 현행 바닥충격음 단일지수 평가 방법에 따라 평가한 결과 측정위치에 따라 단일지수 평가값에 2-7dB의 차이를 보였으며 바닥충격음 차음성능 평가에 영향을 줄 수 있을 것으로 판단되었다. 따라서 향후 저주파 대역의 편차를 줄이거나 저음의 모드 중첩에 의한 영향을 배제할 수 있는 측정 혹은 평가 방식의 개선이 필요하다고 사료된다.

• 동아시아식생활학회지
• /
• 제4권3호
• /
• pp.21-30
• /
• 1994

The relationship between bone mineral density and the environmental factors were investigated from the view point of preventing osteoporosis in Korean pubescent girls. The effects of calcium, nutrient intake, physical activity on total bone mineral density, lumbar spine and femoral bone mineral density and total bone mineral content were evaluated 33 healthy pubescent girls aged 14∼16y. A convenient method was used to assess nutritional and energy intake and calcium index was used together. Calcium intake in childhood was estimated by asking whether subjects usually drank milk as children. Eating habits data and history of menstruation were obtained by questionnaire and interview. Average energy expenditure was calculated. Bone mineral density and content were measured by dual energy x-ray absorptiometry using a Lunar DPX＋Scanner (Lunar, Madison, WI). The lumbar spine(L2∼L4) and three sites in the proximal femur (femoral neck, trochanteric region, and Ward's triangle)were measured. Height and weight were measured, and the body mass index(BMI) was derived from the formula : BMI=kg/㎡ Statistical analysis was performed by simple correlation using the SAS package. The mean calcium intake (736mg) was below the RDA of 800mg/d. Twelve percent of the total subjects did not drink milk at all because they did not like the taste. Skipping meals, low calcium intake and low energy intake were significantly correlated with the low BMD. Also the data indicate that girls who reported drinking milk with every meal during childhood had significantly higher bone densities than girls who reported drinking milk less frequently. The results suggest that milk consumption in childhood appears to be needed not only for growth and development, but possibly also to assure an optimal peak of bone mass and thus greater latitude for the maintenance or skeletal integrity in the face of bone losses. There was a highly significant correlation between the total BMD and overall level of physical activity. Body weight was a better predictor of total BMD than was and other factor. Simple mechanical loading may explain why body weight, but total BMC was positively relatd to height. Conclusively, increasing calcium intake and physical activity in the pubescent girls could influence BMD.

• 대한전자공학회논문지
• /
• 제27권3호
• /
• pp.108-115
• /
• 1990

고속 퓨리어변화(Fast Fourier Transform)연산용 2차원 시스토릭 어레이의 기본 구성요소인 단위 처리요소(Unit processing element)를 직접회로로 설계, 제작하고 제작된 칩을 평가하였다. 설계된 칩은 FFT 연산을 위한 데이타셔플링 기능과 반쪽 버터플라이 연산기능을 수행한다. 약 6,500여개의 트랜지스터로 구성된 이 칩은 표준셀 방식으로 설계되었으며, 2미크론 이중 금속 P-Well CMOS 공정으로 제작되었다. 제작된 칩을 웨이퍼 상태로 프로브카드를 이용하여 평가하였으며 그 결과, 20MHz 클럭 주파수에서 반쪽 버터플라이 연산이 0.5${\mu}sec$에 수행됨을 확인하였다. 본 논문에서 설계, 제작된 칩을 이용하여 1024-point FFT를 연산하는 경우 11.2${\mu}sec$의 시간이 소요될 것으로 예상된다.

• 한국건축시공학회지
• /
• 제5권2호
• /
• pp.115-121
• /
• 2005

The building below standard scales to be built only by constructive report to authorities. Construction law 8 illustrates that supervision should be deployed in all the construction sites at the building which is found to have more than 3 floors and also to have more than loom of total squares in especially outside area of city plan zone. Such a small construction is have a important and the most basic meaning. Many problems were found to occur in all the constructive places which were out of the limit of this law. The construction sites were found to be controlled by public official's visiting without supervisors and designers of architecture. Technique of construction in architecture was found to be not different from that of 1980. The security of employees in construction on sites has a serious problem. Because of choosing ail the materials of the building without a reasonable point. All the building were found to have a law material about inside and outside aspects. The purpose of this study are to examine existing law about a small project and than to analyze the situation of constructive control through questionnaires and interviews with all the supervisors. Based on the data base of engineers who had a great experience in construction sites, The purpose of this study is also to suggest and advise the method of controlling all the items in architecture through on and off line.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년 영문 학술대회
• /
• pp.187-194
• /
• 2008

Because the types and severities of most engine faults are various and complex, it is not easy that the conventional model based fault detection approach like the GPA(Gas Path Analysis) method can monitor all engine fault conditions. Therefore this study proposed newly a diagnostic algorithm for isolating and diagnosing effectively the faulted components of the smart UAV propulsion system, which has been developed by KARI(Korea Aerospace Research Institute), using the fuzzy logic and the neural network algorithms. A precise performance model should be needed to perform the model-based diagnostics. The based engine performance model was developed using SIMULINK. For the work and mass flow matching between components of the steady-state simulation, the state-flow library was applied. The proposed steady-state performance model can simulate off-design point performance at various flight conditions and part loads, and in order to evaluate the steady-state performance model their simulation results were compared with manufacturer's performance deck data. According to comparison results, it was confirm that the steady-state model well agreed with the deck data within 3% in all flight envelop. The diagnosis procedure of the proposed diagnostic system has the following steps. Firstly after obtaining database of fault patterns through performance simulation, then secondly the diagnostic system was trained by the FFBP networks. Thirdly after analyzing the trend of the measuring parameters due to fault patterns, then fourthly faulted components were isolated using the fuzzy logic. Finally magnitudes of the detected faults were obtained by the trained neural networks. Because the detected faults have almost same as degradation values of the implanted fault pattern, it was confirmed that the proposed diagnostic system can detect well the engine faults.

• Journal of Biosystems Engineering
• /
• 제33권5호
• /
• pp.362-369
• /
• 2008

There is developing interest in precision agriculture in Korea, despite the fact that typical Korean fields are less than 1 ha in size. Describing within-field variability in typical Korean production settings is a fundamental first step toward determining the size of management zones and the inter-relationships between limiting factors, for establishment of site-specific management strategies. Measurements of rice (Oriza Sativa L) yield, chlorophyll content, and soil properties were obtained in a small (100-m by 30-m) Korean rice paddy field. Yield data were manually collected on 10-m by 5-m grids (180 samples with 3 samples in each of 60 grid cells) and chlorophyll content was measured using a Minolta SPAD 502 in 2-m by 2-m grids. Soil samples were collected at 275 points to compare results from sampling at different scales. Ten soil properties important for rice production in Korea were determined through laboratory analyses. Variogram analysis and point kriging with and without median polishing were conducted to determine the variability of the measured parameters. Influence of variogram model selection and other parameters on the interpretation of the data was investigated. For many of the data, maximum values were greater than double the minimum values, indicating considerable spatial variability in the small paddy field, and large-scale spatial trends were present. When variograms were fit to the original data, the limits of spatial dependency for rice yield and SP AD reading were 11.5 m and 6.5 m, respectively, and after detrending the limits were reduced to 7.4 m and 3.9 m. The range of spatial dependency for soil properties was variable, with several having ranges as short as 2 m and others having ranges greater than 30 m. Kriged maps of the variables clearly showed the presence of both large-scale (trend) variability and small-scale variability in this small field where it would be reasonable to expect uniformity. These findings indicate the potential for applying the principles and technology of precision agriculture for Korean paddy fields. Additional research is needed to confirm the results with data from other fields and crops.d similar tendency with the result for the frequency less than 20 Hz, but the width of change was reduced highly.

• 한국물환경학회지
• /
• 제29권4호
• /
• pp.514-522
• /
• 2013

The major 24 tributaries in Nam-River mid-watershed were monitored for discharge and water quality in order to understand the characteristics of the watershed and to select the tributary catchment for improving water quality. According to the analytical results of discharge and water quality monitoring data of 24 tributaries, the mean value of discharge below $0.1m^3/s$ was 62.5% among the monitored tributaries and it mostly exceeded the water quality standards of Nam-river mid-watershed ($BOD_5$ = 3 mg/L, T-P = 0.1 mg/L over). According to the stream grouping method and the water quality delivery load density ($kg/day/km^2$) based on the results of tributary discharge and water quality monitoring, the tributary watersheds for improving the water quality were selected. In the Nam-River mid-watershed, tributaries in the GaJwaCheon, HaChonCheon catchment (Group D, $BOD_5$ = 3 mg/L over) and in the UirYeongCheon, SeokGyoCheon catchment (Group A, T-P = 0.1 mg/L over), which have a small flow (and/or large flow) and a high concentrations of water pollutants. The various water quality improving scheme for tributaries, in accordance with the reduction of potential point source pollution by living sewage and livestock wastewater, should be established and implemented.

• 한국정보통신학회논문지
• /
• 제16권9호
• /
• pp.1931-1938
• /
• 2012

무선 센서 네트워크에서 우회 경로는 경로 단절시 목적지에 데이터를 전달할 수 있는 대체 경로이다. 또한 이것은 에너지 낭비를 초래할 수 있는 요인이기도 하다. 이러한 문제점을 해결하기 위하여 멀티패스를 사용하는 방법이 제안되었다. 그러나, 이 방법은 센서노드의 무선 자원을 낭비할 수 있다. 최적의 패스는 에너지 소비를 감소시키기 때문에 네트워크의 수명이 길어지지만, 최적의 패스를 유지하기 위해 전체 노드들 간 주기적인 정보 교환이 이루어져야 한다. 본 논문은 분산된 3차원 센서네트워크에서 최적의 경로를 결정 알고리즘을 제안한다. 제안된 방법은 이웃 노드 간 정보 공유를 통하여 최적의 k-경로를 결정할 수 있을 뿐만 아니라 네트워크의 수명을 연장할 수 있다.

• 대한지하수환경학회지
• /
• 제6권2호
• /
• pp.101-106
• /
• 1999

쓰레기의 단순 매립은 주변 환경에 대해 고려하지 않고 이루어지기 때문에 침출수에 의해서 지하수와 토양이 오염되고 매립가스에 의해서 악취 및 대기오염을 발생시킨다. 본 연구에서는 김포매립지의 침출수 수위저감과 매립가스의 포집 및 제어에 관한 연구를 수행하기 위해 다차원 2상 천이유동 유한차분 전산 모델을 활용하여 침출수와 매립가스의 동시 유동 해석을 시도하였다. 이 전산해석에서는 매립지 상부는 가스 생성량의 58%가 대기로 발산되며. 지하함앙율은 연평균 강수량의 12%로 가정하였다. 이외의 모든 자료들도 1995년 3단 매립 시점의 자료를 이용하였다. 전산 해석결과 매립지 중앙에 위치한 지점에서 수두의 최대값은 26 m$H_2O$(2.52 atm)로 나타났으며. 수평관의 설치는 매립지의 안정화 시점을 앞당기는데 중요한 역할을 한다는 것을 알 수 있었다. 수도권 매립지에서 3단 매립이란 가정과 낮은 지하 함양율을 적용하였음에도 40년이 경과되는 시점에서 침출수는 15.l$\times$$10^{6}$ ㎥, 매립가스는 5.85$\times$$10^{9}$ ㎥ 의 엄청난 양이 누적 생산되었다.

• 한국조경학회지
• /
• 제29권3호
• /
• pp.81-89
• /
• 2001

The purpose of this research is to provide for some useful data for computer-related courses of the landscape science, assuming that computers are being and should be used more and more in landscape architecture and therefore, that landscape science students need to respond positively to such a trend. For this purpose, landscape architecture studios and their landscape architects were surveyed for their computer and its program uses as well as their satisfaction with the utility of computer for their landscape works. The results of this research are as follows; 1) 10.7% of the landscape architects surveyed answered that they had learned about their necessary softwares at school, while 61.6% of the studios surveyed were less satisfied with their employees' poor computing ability. Such findings suggest a lack of computer-related courses in landscape science and therefore, that more computer-related courses should be introduced for landscape science students together with the necessary software education. 2) Too few landscape softwares are being used by the landscape architecture studios; such softwares as AutoCAD, Photoshop, 3D Max, Excel, PowerPoint and 한글 account for more than 90% of the landscape architecture softwares being used currently. Quite naturally, landscape students need to be trained on these softwares above all. 3) It was found hat he area of work using the computer most was ˝design works˝(84.5%), followed by ˝documentation˝(83.8%), ˝image editing˝(75.1%), ˝cost calculation˝(68.2%), ˝presentation˝(68.1%), ˝analysis˝(37.8%) and ˝rendering˝(35%). It was regretable to discover that such areas requiring more computing work as ˝analysis˝ and ˝rendering˝ were still worked manually. So it sis deemed necessary for landscape science courses to enhance their computer education of such areas first of all.