• 대한원격탐사학회지
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• 제34권4호
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• pp.625-638
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• 2018

In this paper, we derive i) a function to estimate snow cover fraction (SCF) from a MODIS satellite image that has a wide observational area and short re-visit period and ii) a function to determine snow depth from the estimated SCF map. The SCF equation is important for estimating the snow depth from optical images. The proposed SCF equation is defined using the Gaussian function. We found that the Gaussian function was a better model than the linear equation for explaining the relationship between the normalized difference snow index (NDSI) and the normalized difference vegetation index (NDVI), and SCF. An accuracy test was performed using 38 MODIS images, and the achieved root mean square error (RMSE) was improved by approximately 7.7 % compared to that of the linear equation. After the SCF maps were created using the SCF equation from the MODIS images, a relation function between in-situ snow depth and MODIS-derived SCF was defined. The RMSE of the MODIS-derived snow depth was approximately 3.55 cm when compared to the in-situ data. This is a somewhat large error range in the Republic of Korea, which generally has less than 10 cm of snowfall. Therefore, in this study, we corrected the calculated snow depth using the relationship between the measured and calculated values for each single image unit. The corrected snow depth was finally recorded and had an RMSE of approximately 2.98 cm, which was an improvement. In future, the accuracy of the algorithm can be improved by considering more varied variables at the same time.

• 한국산학기술학회논문지
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• 제13권8호
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• pp.3666-3671
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• 2012

적외선 거리 센서를 사용하여 취득한 깊이이미지(depth image)에 대하여 잘 알려진 얼굴인식 알고리즘을 수행하여 깊이이미지 응용에 적용가능성을 평가한다. 아울러, 기존의 얼굴인식이 정확도 측면에서만 강조를 해온 측면이 있는데 이렇게 하면 실제 환경에서 적용할 때 문제점을 제대로 평가하기 어렵다. 본 연구에서는 RGB 이미지와 깊이 이미지들에 대해 잘 알려진 얼굴 인식 알고리즘 (PCA, LDA, ICA, SVM)을 적용하여 얼굴인식 정확도뿐만 아니라 처리 속도, 사용 메모리 그리고 저장 공간에 대한 정보를 구해 이미지 유형과 각 알고리즘에 따른 전반적인 성능을 구하였다. 처리 결과 깊이이미지와 컬러 색인된 깊이이미지는 컬러이미지에 비해 각각 30% ~ 40% 정도 파일 크기가 작음에도 전반적인 성능에서 컬러이미지와 마찬가지로 우수한 결과를 보였으며, LDA는 SVM 다음으로 정확도도 우수하고 훈련시간과 훈련 소요메모리도 양호하고 테스트시간과 테스트 소요 메모리도 낮아 우수한 성능을 보였다.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.125-132
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• 2020

The objective of this study was to analyze the axle load of a rice transplanter when planting rice seedlings at different working load conditions to select a suitable gear stage and a constant planting depth for rice seedlings. In this study, there are four levels of planting distances (26, 35, 43, and 80 cm) and three planting depths (low, medium, and high) with two gear stages (1.3 and 1.7 m/s). Axle loads and required planting pressures were analyzed statistically. It was observed that axle torques were increased with increasing planting depths for both gear stages, meaning that axle torques were directly proportional to planting depths for both gear stages. It was also observed that required planting pressures had a significant difference between planting distances. Planting pressures also showed significant difference according to gear stage and planting depth. These results indicate that planting pressures were directly proportional to both gear stage and planting depth. Results revealed that the automatic depth control system of a rice transplanter could not guarantee a constant planting depth as supplied pressures were variable. This indicates that a control algorithm is needed to ensure a constant planting depth. In the future, a control algorithm will be developed for an automatic depth control system of a rice transplanter to improve its comprehensive performance and efficiency.

• 대한소아치과학회지
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• 제27권1호
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• pp.169-179
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• 2000

초기 우식병소와 건전한 치질은 광학적 특성 이 다르다는 사실에 근거하여 치과 치료용으로 개발된 가시광선 영역의 아르곤 레이저의 형광현상, 즉 물체에 조사되어 반사된 및은 물체의 광학적 특성에 따라 파장이 달라지는 특성을 이용하여, 우식 치질과 건전한 치질간의 광학적 특성의 차이를 아르곤 레이저 빛을 통한 색조의 차이로 유도 전환하는 시스템을 개발하고 이를 이용하여 초기 치아우식 병소를 조기에 시각적으로 탐지하여 data화 하는 새로운 우식활성검사법을 개발하는데 본 연구의 목적이 있다. 연구는 3단계로 나누어 1단계는 아르곤 레이저 형광법의 초기 우식병소 탐지능력을 평가하였으며 2단계는 임상에서 아동들을 대상으로 아르곤 레이저 형광법을 이용하여 초기 우식병소가 있는 치아의 갯수를 집계하고 이 수치에 대한 우식활성검사법인 $Cariescreen^{(R)}$ test, 그리고 일종의 구강환경검사인 우식경험치아의 수(dDfFtT) 검사와의 상관성을 평가하였다. 3단계는 이와 같은 자료를 기준으로 하여 레이저 형광법을 이용하여 검사할 수 있는 새로운 우식활성검사 모델을 만들고 이와 같은 검사법의 민감도, 타당도, 진단력 등을 분석하여 진단학적 측면에서 활용 가능성을 평가하고자 하였으며 그 결과는 다음과 같다. 초기 우식병소의 조직학적 깊이가 증가될수록 레이저 형광법을 이용하여 측정한 광밀도가 증가하였으며 이들 사이에는 높은 상관관계 (=0.7015)가 있었다. 또한 통계학적으로 회귀분석을 시행한 결과 병소의 깊이와 광밀도와 사이에는 정비례 관계의 직선방정식 관계를 나타내었다. 레이저 형광법을 이용한 우식활성검사법은 $Cariescreen^{(R)}$ test 그리고 dDfFtT 검사 등과 높은 상관관계를 나타냈다. 또한 레이저 형광법을 이용한 우식활성 검사법은 dDfFtT검사를 기준으로 48%의 민감도, 52%의 특이도, 45%의 진단력을 보였으며 $Cariescreen^{(R)}$ test를 기준으로 48%의 민감도, 51%의 특이도, 36%의 진단력을 보였다. 이상의 결과를 종합하면 레이저 형광법을 이용하여 측정한 초기 우식병소의 광밀도는 실제 초기우식병소의 조직학적병소의 깊이를 평가하는데 높은 진단학적 신뢰성을 보여주고 있으며 레이저 형광법을 이용한 우식활성검사는 진단학적 지표를 기준으로 볼 때, 그리고 검사절차와 시간, 비용 등의 면으로 볼 때 향후 임상적으로 활용 가능성이 높은 것으로 사료된다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.209-216
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• 1999

Prefabricated piles used for construction of highway bridges are most of steel pipe piles and few of prestressed concrete piles. Its installation and inspection are less controllable and have much uncertainty due to changes in subsoil and groundwater conditions. However, most of these piles have been controlled using outdated pile driving formula such as Hiley's formula which models just the energy conservation due to its simple applicability in the field. This formula results in overstriking or sometimes understocking due to buckling of pile head. Engineers cannot ensure by the formula whether pile is installed properly. To compensate the drawbacks of excising pile formula, parameters in Hiley's formula and 55 formula are reviewed. Final sets used in pile formula and PDA test results(E.O.I.D) are measured during pile driving along the depth. These measured results along the depth were compared with each other and with N values, so that relations between the each result could be inferred. Also the factor of safety which can be used for pile driving formula are suggested.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2115-2124
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• 2011

The rail surface defects which are generated on repeated rolling contact fatigue are getting increased according to high speed, high density, and minimum weight. In addition, Increasing noise and vibration are affected by these also impact load generated as well. Because of this phenomenon, more serious and critical damages were occurred. In fact, in order to control them, the rail grinding were conducted. However, there are not enough researches to make an criteria of generating optimal rail grinding amount in Korea. This study evaluated how depth of hardening on rail surface is formed and suggested optimal rail grinding amount by RCF(rolling contact fatigue) test with generated contact pressure between KTX wheel and UIC60 rail by applying FEM analysis. Therefore, the amount was generated approximately 0.2mm/20MGT to maintain integrity of rail surface by getting rid of depth of hardening on rail according to rail accumulated passing tonnage.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2010년도 추계학술대회
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• pp.42-43
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• 2010

본 연구에서는 만타 형상 무인잠수정(Manta-type unmanned underwater test vehicle)의 제어 성능 평가를 하였다. PID제어, Fuzzy 제어가 적용되었으며, 6자유도 운동을 사용하여 Matlab Simulink로 시뮬레이션 프로그램을 구성하였다. 설계된 제어기로 수심 및 방위제어에 사용되었으며 조류의 외란 하에서의 제어 성능을 평가하였다.

• 한국생산제조학회지
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• 제6권1호
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• pp.77-83
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• 1997

In this paper, we have studied internal quality including chemical compositions, microscopic structure and nonmetalic inclusion of test materials. We have analyzed dynamic characteristics of cutting force of milling including tensile strength value, hardness etc. Test materials are used in the tempered carbon steel and the non-tempered carbon steel. The obtained results are as follows: 1. In analyzing internal quality, the tempered carbon steel have typical martensite structure and the non-tempered carbon steel have ferrite + pearlite structure. 2. Yield strength, tensile strength and hardness value are in the non-tempered carbon steel but elongation is maximum value in the tempered carbon steel. 3. Cutting force is smaller non-tempered carbon steel than tempered carbon steel when feed speed and depth on cut is constant. 4. Cutting force is smaller non-tempered carbon steel than tempered carbon steel when cutting speed and depth of cut is constant.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.903-906
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• 2001

The objective of this experimental study was to understand the effect of horizontal shear bar on the shear behavior of R.C. deep beams. Therefore, in the test program, the horizontal shear bar ratio($\rho_{sh}$) and shear span-to-overall depth ratio(a/h) are considered as two main variables. Test results indicate that for deep beams with a/h equal to 1.0, horizontal shear bar is less efficient in restricting the diagonal crack width development and enhancing the ultimate shear strength. So, it can be concluded that shear resistance of horizontal shear bar is related to a/h rather than clear span-to-effective depth ratio($l_{n}$/d) recommended in ACI code.

• Steel and Composite Structures
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• 제19권4호
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• pp.953-966
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• 2015

Carbonation depth was verified in 40 points of two 57 years old concrete viaducts. Field testing (phenolphthalein spraying) was performed on the structures. Data obtained were statistically analyzed by the Kolmogrov-Smirnov's test, one-way analysis of variance (ANOVA's test), and Fisher's method. The results revealed significant differences between maximum carbonation depths of different elements of the same concrete structure. Significant differences were also found in the carbonation of different concrete structures inserted in the same macroclimate. Microclimatic factors such as temperature and local humidity, sunshine, wind, wetting and drying cycles, among others, may have been responsible by the behavior of carbonation in concrete.