• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.37-44
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• 2014

The use of a laser interferometer as a metrological tool in micro-optics measurement is demonstrated. A transmissive interferometer is effective in measuring an optical specimen having a high angle slope. A configuration that consists of an optical resolution of 0.62 micron is adapted to measure a specimen, which is a micro-Fresnel lens-shaped lenticular lens. The measurement result shows a good repeatability at each fraction of facets, however, a reconstruction of the lens shape profile is disturbed by a known problem of $2{\pi}$-ambiguity. To solve this $2{\pi}$-ambiguity problem, we propose a two-step phase unwrapping method. In the first step, an unwrapped phase map is obtained by using a conventional unwrapping method. Then, a proposed unwrapping method based on the shape modeling is applied to correct the wrongly unwrapped phase. A measured height of each facet is compared with a profile result measured by AFM.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.355-358
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• 2015

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group galaxy M33. The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. The pulsating giant stars (AGB and red supergiants) are identified and their distributions are used to derive the star formation rate as a function of age. These stars are also important dust factories; we measure their dust production rates from a combination of our data with Spitzer Space Telescope mid-IR photometry. The mass-loss rates are seen to increase with increasing strength of pulsation and with increasing bolometric luminosity. Low-mass stars lose most of their mass through stellar winds, but even super-AGB stars and red superginats lose ~40% of their mass via a dusty stellar wind. We construct a 2-D map of the mass-return rate, showing a radial decline but also local enhancements due to agglomerations of massive stars. By comparing the current star formation rate with total mass input to the ISM, we conclude that the star formation in the central regions of M33 can only be sustained if gas is accreted from further out in the disc or from circum-galactic regions.

• Journal of Sensor Science and Technology
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• v.14 no.2
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• pp.116-124
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• 2005

In this paper range measurement systems are designed using an ultrasonic sensor and a camera. An ultrasonic sensor provides the range measurement to a target quickly and simply but its low resolution is a disadvantage. We tackle this problem by employing a camera. Instead using a stereoscopic sensor, which is widely used for 3D sensing but requires a computationally intensive stereo matching, the range is measured by focusing and structured lighting. In focusing a straightforward focusing measure named as MMDH(min-max difference in histogram) is proposed and compared with existing techniques. In the method of structure lighting, light stripes projected by a beam projector are used. Compared to those using a laser beam projector, the designed system can be constructed easily in a low-budget. The system equation is derived by analysing the sensor geometry. A sensing scenario using the systems designed is in two steps. First, when better accuracy is required, measurements by ultrasonic sensing and focusing of a camera are fused by MLE(maximum likelihood estimation). Second, when the target is in a range of particular interest, a range map of the target scene is obtained by using structured lighting technique. The systems designed showed measurement accuracy up to 0.3[mm] approximately in experiments.

• Journal of Korean Society for Quality Management
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• v.50 no.3
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• pp.425-440
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• 2022

Purpose: The purpose of this paper is to improve the chromaticity coordinate quality of white LED packages for automobiles that require high quality and reliability. Methods: The project follows the structured methodology of the Six Sigma DMAIC Roadmap, which consists of Define, Measure, Analyze, Improve and Control phases. Results: A CTQ is determined based on COPQ analysis, and a process map and a XY matrix are utilized for selecting process input variables. Three vital Few Xs are identified through data analysis; amount to mix at one time, deviation by head pumps, and deviation by production magazines, and process improvements are performed for each of the three vital Few Xs. Conclusion: The improved process conditions for the three vital Few Xs are applied to the production line, and the results show that the percent defective of chromaticity coordinate has improved from 1.59% to 0.63% and a financial effect of about 50 million won per year is obtained.

• Journal of the Korea Safety Management & Science
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• v.25 no.3
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• pp.9-15
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• 2023

As the first step of risk management, risk identification is inevitable to understand the degree of work safety. However, the safety requirements can be divided in necessary factors and additional factors. Thus, we propose a safety requirements assessment model using Kano model derived from Herzberg's two-factor theory, classifying safety requirements into ideal elements and must-be elements. The Kano model is usually applied to evaluate customer satisfaction divided into three major requirements in the fields of product development and marketing: attractive, must-be, and one-dimensional requirements. Among them, attractive requirement and must-be requirement are matched with ideal element and must-be element for safety requirement classification, respectively. The ideal element is defined as preventive safety elements to make systems more safe and the must-be element is referred to as fatal elements to be essentially eliminated in systems. Also, coefficients of safety measurement and safety prevention are developed to classify different class of safety requirements. The positioning map is finally visualized in terms of both coefficients to compare the different features. Consequently, the proposed model enables safety managers to make a decision between safety measurement and prevention.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.4
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• pp.543-558
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• 2023

Currently, Japan is undertaking a nationwide project to measure and map radioactive contamination around Fukushima, as part of the efforts to restore normalcy following the nuclear accident. The Japan Atomic Energy Agency (JAEA) manages the Fukushima Environmental Safety Center, located approximately 20 km north of the Fukushima Daiichi nuclear power plant in Minamisōma City, Fukushima Prefecture. In collaboration with the JAEA, this study involved conducting comparison experiments and analyses with radiation detectors in high radiation environments, a challenging task in Korean environments. Environmental radiation surveys were conducted using three types of detectors: CZT, NaI(Tl), and LaBr₃(Ce), across two contaminated areas. Dose rate values were converted using dose rate conversion factors for each detector type, and dose rate maps were subsequently created and compared. The detectors yielded similar results, demonstrating their feasibility and reliability in high radiation environments. The findings of this study are expected to be a crucial reference for enhancing the verification and supplementation of procedures and methods in future radiation measurements and mobile surveys in high-radiation environments, using these three types of radiation instruments.

• Journal of The Korean Association For Science Education
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• v.29 no.4
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• pp.388-399
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• 2009

This study was designed to investigate whether applying mind mapping in a biology class had an effect on students' creativity. Participants of this study were 165 1st grade middle school students. The pretest-post test control group design was employed. A control group was instructed with a traditional method and an exerimental group was instructed using the mind-map applied method. The units "Digestion and Circulation" and "Respiration and Excretion" were selected for this study, and each group was treated for 24 class hours. To measure student creativity, the TTCT test was used. For assessing students' level of logical thinking, the compact version of GALT was used. Test results were analyzed by ANCOVA and correlation analysis by SPSS 12.0. The creativity of students in experimental group was significantly improved than the control group (p< .01). Fluency, flexibility, and originality of students in experimental group were improved (p< .01). Students did not show any differences on creativity according to their academic achievement level or gender (p> .05) in the experimental group. Students did not show any differences on creativity according to their logical thinking level (p> .05), either. However, the students of logical thinking level in the experimental group improved their flexibility (p< .05). There was no correlation between students' creativity and their achievement (p> .05), but the creativity shows a lower correlation to performance evaluation (p< .05).

• Annual Conference of KIPS
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• 2007.11a
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• pp.104-107
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• 2007

인간은 초점정보를 이용하여 단안만으로도 공간의 깊이를 지각할 수 있다. 이것은 한 번에 하나의 대상물에만 초점을 맞출 수 있고 그 외의 부분은 흐림 현상을 유도함으로써 이루어진다. 이는 초점이 맞는 대상물체로부터 멀어지면 멀어질수록 흐림 현상이 강해지는 원리를 이용한 것으로 주파수 성분의 변화량에 대한 연산과 깊은 관련이 있다. 본 논문에서는 이와 같은 인간의 시각 시스템의 요소 중 하나인 초점정보를 모방하여 초점거리가 다른 각각의 이미지들에 각각의 가중치를 부여하였다. 그리고 각 이미지들을 일정 블록으로 각각 분할하여 초점이 가장 잘 맞는 블록을 찾아내어 하나의 이미지로 통합하였다. 이때 각 영역은 자신이 속했던 이미지의 가중치를 따르게 한다. 각 이미지에서 가장 포커스 수치가 높은 영역을 찾기 위한 방법으로 주파수 영역 기반 처리와 공간 영역 기반 처리를 결합 하였다. 주파수 기반으로는 FFT(Fast Fourier Transform)에서 고주파 부분의 영역을 뽑아내어 포커스수치를 계산하였으며, 공간 영역 처리 기반으로는 이웃픽셀과의 차이가 임계값이하인 것을 제외한 영역을 뽑아내어 저주파 영역의 연산을 제거하는 방법과 단순히 Laplacian measure만을 사용하여 저주파까지도 포함한 방법의 두 가지를 적용하였다. 최종적으로 3개의 포커스 측정값을 결합시켜 포커스 수치를 계산한 후 각 블록의 가중치에 맞게 하나의 이미지로 통합하여 상대적 깊이지도를 생성하였다.

• International journal of advanced smart convergence
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• v.13 no.3
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• pp.259-266
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• 2024

One of the most time consuming issues in a city development is the identification of suitable areas for urban infrastructures and proper land uses. Suitability analysis is the process and procedures to find the best available land in given area -that is, the ability of a system to select the needs of users in land use. This paper studied the usage of Geographic Information System technique and methods for the selection of the most appropriate sites for public park in the city of Gwangju. GIS was used as a standard technique to find the best available sites for development in urban areas. For this cause, digital elevation model and spatial data were used to produce different thematic layers by using software Idrisi. Criteria for finding the suitable site for park development were decided to evaluate the land and the followings 4 criteria were selected: on land with less than 3 degrees in slope, outside a 200m buffer around lakes, on land currently designated as forests, and 20ha or greater in size. To meet and measure each criterion, distance and context operators were applied to reclassify the importance of certain weight and Boolean images were generated to meet the criteria. These weights and maps has been combined using ArcGIS tools and the final map was prepared showing the most suitable sites. We may assist city planners and government officials in future development of public facilities including parks and related land use plans at urban level and act as to ensure proper land use planning and management of the urban areas.

• Progress in Medical Physics
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• v.23 no.1
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• pp.33-41
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• 2012

For applying the quality assurance (QA) of volumetric modulated arc therapy (VMAT) introduced in Eulji Hospital, we classify it into three different QA steps, treatment planning QA, pretreatment delivering QA, and treatment verifying QA. These steps are based on the existing intensity modulated radiation therapy (IMRT) QA that is currently used in our hospital. In each QA step, the evaluated items that are from QA program are configured and documented. In this study, QA program is not only applied to actual patient treatment, but also evaluated to establish a reference of clinical acceptance in pretreatment delivering QA. As a result, the confidence limits (CLs) in the measurements for the high-dose and low-dose regions are similar to the conventional IMRT level, and the clinical acceptance references in our hospital are determined to be 3 to 5% for the high-dose and the low-dose regions, respectively. Due to the characteristics of VMAT, evaluation of the intensity map was carried out using an ArcCheck device that was able to measure the intensity map in all directions, $360^{\circ}$. With a couple of dosimetric devices, the gamma index was evaluated and analyzed. The results were similar to the result of individual intensity maps in IMRT. Mapcheck, which is a 2-dimensional (2D) array device, was used to display the isodose distributions and gave very excellent local CL results. Thus, in our hospital, the acceptance references used in practical clinical application for the intensity maps of $360^{\circ}$ directions and the coronal isodose distributions were determined to be 93% and 95%, respectively. To reduce arbitrary uncertainties and system errors, we had to evaluate the local CLs by using a phantom and to cooperate with multiple organizations to participate in this evaluation. In addition, we had to evaluate the local CLs by dividing them into different sections about the patient treatment points in practical clinics.