• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.864-868
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• 2005

This paper develops an analysis model of a piezoelectric transducer. The transducer considered in this paper is a bolt-clamped Langevin-type transducer, which consists of a couple of piezoelectric discs, a couple of metal blocks for added mass effect, and a bolt to tighten them. A new analytical model for the transducer has been developed by taking into account the contact area between the piezoelectric ceramic and the metal block. The analysis model is verified by calculating the variations of the resonance frequency due to the contact area and comparing them with reported experimental results.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1999년도 제12회 학술강연회논문집
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• pp.24-24
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• 1999

This study addresses the effectiveness of TEC(Thermoelectric cooler) application for spacecraft thermal control. The required radiator area and power consumption characteristics of active thermal control using TEC are compared with the passive control at BOL and EOL through unsteady thermal analyses by calculating external heat fluxes. When the component operating temperature is low enough in TEC active control, the required radiator area can be smaller than the passive thermal control. TEC also needs less power consumption than the passive control under the condition that the temperature of cooling pars is low enough and/or the design temperature margin of the components is narrow enough.

• Bulletin of the Korean Chemical Society
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• 제9권4호
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• pp.244-248
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• 1988

Multilayer adsorption isotherms of nitrogen on hexagonal boron nitride, ${\gamma}$-alumina, and silica-gel powders are determined at the liquid nitrogen temperature using a gravimetric adsorption apparatus. The volume (V) of the adsorbed gas are plotted against the statistical thickness(t) of the adsorbed layer, and the t-method area are calculated from the slope of these V-t plots to compare with the BET area. A number of universal adsorption isotherms and the Frenkel-Halsey-Hill equation are used one after another in calculating the statistical thickness. The appropriateness of the FHH equation as an universal adsorption isotherm is discussed finally.

• 한국보건간호학회지
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• 제4권2호
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• pp.5-13
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• 1990

The purpose of this study was to investigate physical self concept between high school boys and girls and to find various factors affecting them. For the Survey, 331 respondents for boys and 347 for girls were randomly selected from one coeducational high school in Seoul, from May 16 to May 19, 1990. The instrument used in this questionaire survey method was a part of Won Shik Jung's Physical Self Concept Scale for measuring Self Concept, it's reliability was' Cronbach a = 0.718. For the analysis. descriptive statistics were used by calculating frequencies, percentages and mean scores. $X^2-test$, t-test, and analysis of variance were employed to test the differences and statistical significance. The relationship between physical self concept and area variables was analysed by use of Pearson's correlation coiefficients. For the examine of various factors affecting physical self concept, multiple stepwise regression method was employed. The results of this study are summarized as follows: 1. There was no significant difference in physical self concept between male and female students. 2. The scores of physical self concept among the students were negatively correlated with their academic year, even though statistical signification was not found. 3. Physical self concept was classified into two areas; health area and appearance area. There was no significant difference in health area between boys and girls. But, the difference of health area was significant in accordance with the academic years. That, the scores of the health area are dropped as academic year going up. 4. Significant relationship was revealed among health area, appearance area, and physical self concept. The correlation between health area and physical self concept was the highest relationship (r = 0.71) The main factors affecting the physical self concept were (1) father's educational background (2) year (3) number of brother (4) religion (5) father's age. 5. As academic year going up, the rate of counseling with parents are dropped. In conclusion, the result of the study indicate that, a person managed the school health and parents can help students to promote their physical, mental, and emotional health by means of health education and counseling.

• 한국물환경학회지
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• 제30권2호
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• pp.128-137
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• 2014

The land use of the unit watersheds should be maintained appropriately in order to keep the load allotment stable for the management of Total Maximum Daily Loads (TMDLs). This study classified the land area in four types and analyzed the use of each land type and its changing pattern by calculating the occupation and conversion ratios for the unit watersheds in three river basins. The forest land showed the greatest occupation ratio with 63.0%, followed by the farm land with 23%, the other area with 8.0% and the site area with 6.0% in 2003. The occupation ratio of the site and the other area increased by 0.4% and 0.2% respectively, and that of the farm and the forest land decreased by 0.4% and 0.2% respectively in 2007. The conversion ratio for the site area ranged from 1.65% to 1.97%, for the farm land from -0.47% to -0.33%, for the forest land from -0.10% to -0.04% and for the other area from 0.17% to 1.97%. It can be inferred that the decrease in the farm and the forest land contributed to the increase in the site area and that the increase in the other area was mainly made by the decrease in the forest land. It could be more effective to take into account the changes in the site area and in the forest land in the process of developing the TMDL plans.

• 생물환경조절학회지
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• 제24권3호
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• pp.135-146
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• 2015

본 연구는 온실에 작용하는 풍하중 산정을 위한 설계 풍속을 결정하는데 필요한 자료를 제공하기 위하여 10m 이하 높이에서의 풍속을 측정하여 풍속고도분포지수를 산정하고 변화를 분석하였다. 고도에 따른 풍속분포함수를 결정하기 위한 풍속고도분포지수를 계산하기 위해서는 $5m{\cdot}s^{-1}$ 이상의 풍속을 사용하는 것이 타당하다고 판단된다. 농촌 개활지인 부안지역의 고도에 따른 풍속변화는 지표면으로부터 풍속이 지수함수로 증가하는 우리나라의 RDC 기준과 일본의 JGHA 기준과 잘 일치하였고 풍속고도분포지수도 0.26으로 기준들에서 제시된 0.25와 거의 동일한 값을 나타내었다. 반면 군위지역의 경우는 풍속고도분포지수가 0.06으로 산정되어 지표면조도가 클수록 풍속고도분포지수가 증가하는 일반적인 변화 경향과는 반대로 나타났다. 이는 타워가 주변지대보다 약 2m 가량 더 높은 위치에 설치되었기 때문에 유선의 급격한 변화에 의한 것으로 판단된다. 따라서 일반적으로 농촌 개활지에 설치되는 온실의 설계를 위해 적용할 풍속고도분포로는 우리나라의 RDC기준과 일본의 JGHA기준에서 제시한 풍속고도분포가 가장 타당한 것으로 사료된다. 부안의 경우 오전 7시 경부터 풍속고도 분포지수가 감소하다가 오후 3시경에 최소가 된 후 다시 증가하여 24시경에 일정해지는 것으로 나타나 시간에 따른 풍속고도분포지수의 일반적인 변화경향과 잘 일치하였다. 부안지역은 형상변수가 1.51로 나타나 간척지인 부안지역의 풍속특성이 제주도 연안지역과 유사한 풍속특성을 가지고 있음을 확인하였다.

• 한국실내디자인학회논문집
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• 제19권1호
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• pp.180-189
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• 2010

Since collective houses are started to be supplied, the housing market has been transformed from supplier to demander oriented, and various type with same area of unit households have been deigned and started to be distributed. It can be expected that such transfer phenomenon would be continuously sped-up, and unit household will be more subdivided and varied. Thus, we analysed and studied the planes with subject of unit households in national housing scale ($85m^2$) that is treated as supply standard and has biggest volume in construction by Korean housing corporation. The analysing method is investigating the area of each room within unit household, calculating their minimum, maximum, and average values, studying the efficiency of unit household plane according to the structure of each room by comparative analysis these values, and analysing changing matter by investigating any change of each room area. The analysing results of which are followings. At first, number of BAY on face is increasing. Second, allocation of each room has been vary. Third, area ratio among bedroom1, livingroom, diningroom/kitchen become similar. Fourth, the area of diningroom/kitchen become somewhat bigger. Fifth, the space for passage way is efficiently allocated. Sixth, service area is reduced, Seventh, stereotyped phenomenon Is appeared. Based on many studies so far, any improvements of unit householder in national housing scale are followings. First, in terms of forming style, unit householder in national housing scale is unfolded in various way though, the form of each room is not more than typical style. Second, it shows stereotyped phenomenon. Especially, bathroom 1, 2 show stereotyped feature in terms of their type and area across entire research years, also LDK allocation method is stereotyped, as well as stereotyped trend in bedroom 2, 3, allocation for 4 BAY type.

• 지적과 국토정보
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• 제52권1호
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• pp.95-104
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• 2022

본 연구는 2019년 4월 4일 강릉시 옥계면에서 발생한 산불 피해지역의 정확한 면적을 구하는 것을 목적으로 한다. 우리나라의 산림은 경사도가 존재하고 있으므로 평면적이 아닌 경사를 고려한 표면적을 구해야 한다. 국토지리정보원에서 제공하고 있는 DEM과 산림청에서 제공하는 제5차 수치임상도를 사용하였다. DEM에서는 각 화소의 중심점을 생성하고 모든 점을 연결하였다. 이때 연결선의 길이는 화소의 공간해상력과 cosine값을 통해 결정되며 높이값과 함께 표면적을 구하며, 이를 Slope-Aspect 알고리즘이라 한다. 산림의 표면적과 평면적을 나무의 수종, 산림의 종류에 따라 나타냈으며 이들의 정량적인 수치 차이를 통해 본 연구의 유효성을 입증하였다.

• 농촌계획
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• 제29권4호
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• pp.117-125
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• 2023

This study aimed to analyze the recent status and changes in impervious surface areas and their ratios across regions in Gyeongsangnam-do, providing fundamental data for regional development and impervious surface management. Based on the 'Guidelines for Calculating Water Cycle Management Indicators for Nonpoint Pollution Source Control(Ministry of Environment)', we processed the land characteristics survey map(shapefile) from 2018 and 2022 to analyze impervious surface area and their rates by administrative boundaries. The impervious surface area in Gyeongsangnam-do increased from 75,652 ha in 2018 to 81,055 ha in 2022, with the rate rising by 0.51% from 7.18% to 7.69%. The average of impervious surface area across 545 eupmyeon units expanded by approximately 9 ha, from 139.8 ha in 2018 to 148.8 ha in 2022, with the rate increasing by 0.71%. Concurrently, the whole population declined by 2.8% while the number of households surged by 6.4%, correlating with the growth in impervious areas. Despite population decreases, factors such as population migration, increased household fragmentation, new residential developments, and industrial facility expansions have consistently contributed to the rise in impervious surface area. Notably, even in areas with high impervious surface area rate, significant disparities existed between urbanized areas and predominantly rural regions. Furthermore, about 333 units(61% of the whole eupmyeons), showed negligible changes in their impervious surface area rate, with an increase of less than 0.5%.

• Steel and Composite Structures
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• 제48권1호
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• pp.27-41
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• 2023

Under the long-term effect of corrosive environment, many cold-formed steel (CFS) structures have serious corrosion problems. Corrosion leads to the change of surface morphology and the loss of section thickness, which results in the change of instability mode and failure mechanism of CFS structure. This paper mainly investigates the elastic local buckling behavior of corroded CFS columns. The surface morphology scanning test was carried out for eight CFS columns accelerated corrosion by the outdoor periodic spray test. The thin shell finite element (FE) eigen-buckling analysis was also carried out to reveal the influence of corrosion surface characteristics, corrosion depth, corrosion location and corrosion area on the elastic local buckling behaviour of the plates with four simply supported edges. The accuracy of the proposed formulas for calculating the elastic local buckling stress of the corroded plates and columns was assessed through extensive parameter studies. The results indicated that for the plates considering corrosion surface characteristics, the maximum deformation area of local buckling was located at the plates with the minimum average section area. For the plates with localized corrosion, the main buckling shape of the plates changed from one half-wave to two half-wave with the increase in corrosion area length. The elastic local buckling stress decreased gradually with the increase in corrosion area width and length. In addition, the elastic local buckling stress decreased slowly when corrosion area thickness was relatively large, and then tends to accelerate with the reduction in corrosion area thickness. The distance from the corrosion area to the transverse and longitudinal centerline of the plate had little effect on the elastic local buckling stress. Finally, the calculation formula of the elastic local buckling stress of the corroded plates and CFS columns was proposed.