• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.573-586
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• 2012

Point clouds acquired by a LIDAR(Light Detection And Ranging, also LADAR) system often contain erroneous points called outliers seeming not to be on physical surfaces, which should be carefully detected and eliminated before further processing for applications. Particularly in case of LIDAR systems employing with a Gieger-mode array detector (GmFPA) of high sensitivity, the outlier ratio is significantly high, which makes existing algorithms often fail to detect the outliers from such a data set. In this paper, we propose a method to discriminate outliers from a point cloud with high outlier ratio acquired by a GmFPA LIDAR system. The underlying assumption of this method is that a meaningful targe surface occupy at least two adjacent pixels and the ranges from these pixels are similar. We applied the proposed method to simulated LIDAR data of different point density and outlier ratio and analyzed the performance according to different thresholds and data properties. Consequently, we found that the outlier detection probabilities are about 99% in most cases. We also confirmed that the proposed method is robust to data properties and less sensitive to the thresholds. The method will be effectively utilized for on-line realtime processing and post-processing of GmFPA LIDAR data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.2147-2156
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• 2013

This study aims to analyze the evaluation of the residential environment on the permanent rental housing in Busan. The Permanent Rental Housing policy is one of the special measures which contribute to getting the low-income urban dwellers settled in places of their own. Unfortunately the government has focused on expanding the quantity of housing even though housing doesn't mean just a physical object but the foundation of life. So the occupants who answered the survey lived in the permanent rental housing which were constructed by Busan Metropolitan Corporation. The purpose of the study is to give suggestions which can make up for dissatisfaction and apply preference of occupants based on the results of the research. The result of this study is in following; there were few significant managerial variables determinants of residential satisfaction. And significant variables are; position of rooms and bathroom facilities in internal building characteristics, color of apartment and playground in exterior building characteristics, commuting distance and viewshaft in locational characteristics. Therefore, the government needs to use cutting edge housing technologies aimed at improvement of residential environment and achievement of affordable expense simultaneously.

• Progress in Medical Physics
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• v.8 no.1
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• pp.53-67
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• 1997

General hospitals have being under the influence of various and specific environment of electromagnetic field. The factors are development of medical electric equipment and device with enlarged functional demands, in high power and multi-frequency. It has all of both faces, EMI(electromagnetic interference) and EMS(electromagnetic susceptibility). In additional, expansion of personal communication system(cellular phone) has many unreliable factor of using time and area, making noise of electromagnetic fields. We studied actual conditions of EMI in the medical site, where is numerous medical equipment, especially central operation room and ICU(intensive care unit), AKR(artificial kidney room : hemo-dialysis unit), etc. The influence, most of medical equipments made electromagnetic nosie has various factors in its band of frequency, harmonics and strength. In the experimental use of electro-surgical unit and cellular phone, noticeable and considerable noise of eletromagnetic fields were measured. All of that can make trouble and errors on the steadiness of bioelectrical devices. In conclusion, It is necessary to reconsiderations of reallocating EMI source vs. EMS factor, and set to definite forbiding area of using cellular phone. For maintenance of steady normal conditions, in spite of existing any other legal standards of safty level, it need considering all of alternative electromagnetic situations on a case-by-case basis.

• Progress in Medical Physics
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• v.8 no.1
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• pp.25-29
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• 1997

Ir-192 source activity for high dose rate brachytherapy is measured using Farmertype ionization chamber. The source-to-chamber distance is 10 cm and the measured charge unit is converted to activity unit. The measured values are compared to the values provided from vendor. Because of time dependency of Ir-192 source activity, the activities are regularly checked and compared to calculated values. As the accuracy of Ir-192 source activity is depend on the mechanical measurement setup, we estimated the precision of remote controlled source dwell position using home-made device and film scanner. The difference between measured and predicted dwell position is within 1 mm. As a result, the errors of source activity are 0.7${\pm}$1.5 ％ for measured and vendor-provided values and 0.l${\pm}$1.2％ for measured and time-dependent calculated vlaues. In conclusion, our measured activity has been comparable to the values provided from vendor and our brachytherapy unit has been very accurate until now. Regular quality control of brachytherapy is essential for successful treatment which depends on the accuracy of source position and activity.

• 한국해양학회지
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• v.25 no.2
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• pp.62-73
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• 1990

An experimental study is performed in order to catch the characteristics of the flow field at arrested salt wedge, using a rectangular open channel. Arrested salt wedge is generally so stable that the observations are easy, but velocities and interfacial waves are measured with the aid of visualization method, by injection of fluorescent dyes. The density interface, which is defined as the zone of maximum density variation with depth, exists in about 0.5 cm below the visual interface, and vertical density profile is quite well satisfied with Homeborn model. Interfacial layer has high turbulent intensity and its thickness decreases as the overall Richardson number increases and has magnitude of roughly 17% of upper layer. Cross-sectional velocity distribution just shows the influence of a side-wall friction and in the upper layer vertical velocity profile also becomes uniformly as Reynolds number increases, but in the lower layer it shows nearly parabolic type. Supposes that we divide salt wedge into three domains, that is, river mouth, intermediate and tip zone, entertainment coefficient is small at the intermediate zone and large at the river mouth and the tip zone. River mouth or intermediate zone has comparatively stable interface and capillary wave therefore s produced and propagated downstream. On the other hand, tip zone is very unstable, cusping ripple or bursting ripple is then produced incessantly. Arrested salt wedge form is nearly linear and has no relation to densimetric Froude number and Reynolds number.

• Progress in Medical Physics
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• v.19 no.4
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• pp.291-297
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• 2008

The purpose of this study is to optimize a parallel-hole collimator for small gamma camera having the pixellated crystal array and evaluate the effect of crystal-collimator misalignment on the image quality using a simulation tool GATE (Geant4 Application for Tomographic Emission). The spatial resolution and sensitivity were measured for the various size of hexagonal-hole and matched square-hole collimators with a Tc-99m point source and the uniformity of flood image was estimated as a function of the angle between crystal array and collimator by misalignment. The results showed that the spatial resolution and sensitivity were greatly improved by using the matched collimator and the uniformity was reduced by crystal-collimator misalignment.

• The Journal of the Korea Contents Association
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• v.13 no.3
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• pp.444-455
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• 2013

The purpose of this study is to explore the selection attributes for parents of children with language disability when choosing a clinic. The data collection was carried out in 3 steps: the preliminary survey, first open survey and second survey in AHP(Analytic Hierarchy Process). The subjects of were 252 in total. The results were as follows: First, The order of priority attributes in superior categories for parents of children with language disability when selecting a clinic were 'therapist-related attributes', 'program-related attributes' and 'physical-related attributes' in turn. The top 5 priority attributes in subcategories were 'therapist's academic background and major', 'ability to make a rapport', 'clinical experience and qualification of therapist', 'kindness and confidence' and 'counseling program for parents'. Second, The parents of preschoolers age 6 and younger chose 'clinical experience and qualification of therapist', 'counseling program for parents' and 'learning materials' for the most priority attributes, whereas the parents of students age from 7 to 12, considered 'therapist's academic background and major', 'clinical fee' and 'distance transport parking' more importantly to select a clinic. The results of this study provided preliminary data for successful planning of speech and language therapy.

• Food Science and Preservation
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• v.19 no.1
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• pp.47-53
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• 2012

UV light irradiation is known to give beneficial effects on fresh produce preservation. A container system equipped with UV-LED was fabricated for storing cherry tomatoes under computer-controlled conditions of intermittent on-off cycles (1 hour on/1 hour off). Wavelength (365 and 405 nm) and physical location of the LED (2 and 5 cm above fruit) were studied as variables affecting the respiration, ethylene production and quality preservation of the fruits at 10 and $20^{\circ}C$. 365 nm wavelength gave much higher radiation intensity than 405 nm, and intensity on surface decreased in inverse proportion to square of distance from LED. When compared to non-irradiated control, UV-LED irradiation decreased the respiration by 5-10% at $10^{\circ}C$ while there was no obvious effect at $20^{\circ}C$. Ethylene production was reduced when the fruits were placed at 5 cm distance, while there was no significant difference from control at 2 cm location. The reduction of ethylene production at 5 cm was more pronounced at $20^{\circ}C$. UV-LED irradiation was shown to have delayed increase or lower concentration in carotenoids compared to control treatment. Any negative effect of UV-LED irradiation on ascorbic acid content and firmness was not observed.

• Progress in Medical Physics
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• v.26 no.4
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• pp.241-249
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• 2015

As radiation therapy is one of three major cancer treatment methods, many cancer patients get radiation therapy. To exposure as much radiation to cancer while normal tissues near tumor get little radiation, medical physicists make a radiotherapy plan treatment and perform quality assurance before patient treatment. Despite these efforts, unintended medical accidents can occur by some errors. In order to solve the problem, patient internal dose reconstruction methods by measuring transit dose are suggested. As feasibility study for development of patient dose verification system, inverse square law, percentage depth dose and scatter factor are used to calculate dose in the water-equivalent homogeneous phantom. As a calibration results of ionization chamber and glass dosimeter to transit radiation, signals of glass dosimeter are 0.824 times at 6 MV and 0.736 times at 10 MV compared to dose measured by ionization chamber. Average scatter factor is 1.4 and Mayneord F factor was used to apply percentage depth dose data. When we verified the algorithm using the water-equivalent homogeneous phantom, maximum error was 1.65%.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.281-302
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• 1987

의치상 재료 종류에 따라 의치, 점막 및 하악골에 발생되는 변위 및 응력을 연구하기 위하여 컴퓨터를 이용한 수치적 해석인 2차원 유한 요소법을 이용하였다. 2차원 유한 요소 모형으로선 표준 크기의 하악골 및 의치를 고려하여 231개의 사변형 요소 및 268개의 절점으로 분할한 후 각 구성 성분의 물리적 성질인 탄성률 및 프와송비를 대입시켰다. 사용된 의치로서는 일반 합성수지의치, 2mm후경의 탄성재를 의치상 하부에 이장한 합성수지의치, 2mm후경의 탄성재를 치아와 의치상 중앙에 삽입한 합성수지의치 및 0.5mm후경의 금속상의치의 4종류였으며, 하중시에 하악의 고정 부위로선 생체와 동일 조건을 부여하기 위하여 교근, 내측익돌근, 측두근등의 하악 폐구근이 부착되는 하악각 부위 및 하악 근돌기 부위의 16절점을 고정점으로 하였다. 하중 조건으로선 하악 제1대구치의 일점에 10kg의 수직 집중하중, 하악 중절치의 일점에 7kg의 수직 집중하중 및 하악 제 1소구치로 부터 하악 제2대구치까지의 교합면에 10kg의 수직 분산하중을 부여하여 분석한 결과는 다음과 같다. 1. 하중이 의치 교합면위의 가해진 부위에 따라 다양한 의치 회전 및 강하 현상을 보였으며, 탄성재를 이장 및 삽입한 합성 수지 의치의 변위가 일반 합성수지의치 및 금속상 의치의 변위보다 더 컸다. 2. 주응력을 고려할때 점막 부위에는 주로 압축 응력이 작용하였으며 치조제 부위는 압축응력과 인장 응력이 함께 작용하였다. 3. 탄성재를 삽입한 합성수지의치에 최고 등가 응력이 집중되었으며 그 다음은 탄성재를 이장한 합성수지의치, 일반 합성수지의치의 순이였으며 금속상의 경우는 금속을 따라서 높은 등가 응력이 넓게 분산되었다. 4. 의치상 종류에 관계없이 동일 하중 조건하에선 점막에 나타나는 등가 응력의 크기 및 분산양태는 유사하였다. 5. 하악골에서 등가 응력은 의치지지 부위에만 국한되지 않고 넓게 분산 되었으며 의치상 종류 및 하중 조건에 관계없이 치조제 후방 및 하악연의 후방 부위에 특히 높은 등가응력이 집중되었다. 6. 하악 중절치의 일점에 수직 하중을 가한 경우가 다른 하중 조건에 비하여 지지점과의 거리차이로 인하여 하악골에 가장 높은 등가 응력을 유발하였다. 7. 의치상 재료에 따른 하악 골에 발생되는 응력의 크기 및 분산에는 큰 차이가 없으나 금속상의 경우가 교합압을 분산하는데는 효과적이었다.