• Journal of Technologic Dentistry
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• v.40 no.4
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• pp.231-237
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• 2018

Purpose: The development of the dental technology industry has digitized the dental process. Definition of Digitalization of Dental Implantation Digitalization is the process of model making and prosthodontic processing using 3D CAD and CAM. Currently, it is becoming popular due to the spread of various devices. However, precision evaluation at this stage is an important factor in precision-based dental procedures. Therefore, in this study, we want to analyze the precision of the processed body made with digital dental machine. Methods: The accuracy of digital dental pore devices was evaluated. Specimens were fabricated with 5 types of 3D printers. The external shape was measured with the prepared specimen. The surface roughness was measured. Results: As a result, precision was excellent in order of EP2 specimen, EP1 specimen, and EA2 specimen. The precision of EP3 specimen and EA1 specimen is not excellent. And the precision of the specimen processed with polymer 3D printer is excellent. The accuracy of LCPS type polymer 3D printers is considered to be excellent. Conclusion : 1. Observation of the shape The 3D printer for LCPS system and the 3D printer for SLM $40{\mu}m$ system were found to be precisely processed. 2. Surface roughness results The LCPS system polymer 3D printer has been shown to have a precise surface.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.7-7
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• 2019

우리나라에서의 대마는 마약류로 분류되어 기호용과 의료용 모두 법적인 제재를 받아왔으나 최근에 의료용 대마가 법적으로 허용이 되어 환자들에게 처방 받을 수 있게 되었다. 하지만 우리나라 사람들에게 대마는 환각성분을 가진 마약류로 깊이 인식되어 왔으며 의료용 대마에 대한 연구는 거의 전무한 실정이다. 노지재배에서 발생할 수 있는 범죄의 위험성, 자연교배에 의한 품질저하를 피할 수 있으며 재배조건(양액, 광조건, 광주기, 대기환경조성) 등을 제어할 수 있는 밀폐형 LED 식물공장은 의료용 대마 생산에 제일 적합한 모델이 될 수 있다. 식물체의 광합성은 가시광선 중 특정 파장 450nm 청색광과 660nm 적생광을 주로 이용하며 'LED (Light Emitting Diode) 발광다이오드'는 식물체의 광합성에 적합한 파장으로 광원을 조사할 수 있는 장점이 있다. 이러한 LED를 이용한 광합성은 식물체의 2차 대사물질 Anthocyanins, phenolic compounds 등의 향상과 생육에도 긍정적인 영향을 미치며 식물 뿐만 아니라 광합성을 하는 미세조류(micro algae)에서도 이용이 가능하며 해마토 코쿠스(Hematococcus)의 세포증식과 항산화물질 아스타잔틴(astaxathin)생산에 유용하게 쓰이고 있다. 최근 미국과 다른 나라에서도 기호용, 의료용 대마사업에 대한 관심이 높아지고 있으며 캐나다와 미국에서는 밀폐형 유리온실과 식물공장을 이용한 의료용 대마를 생산, 추출, 가공까지 하여 산업적인 영역을 넓히고 있는 실정이다. 특히, 실내재배에서는 광원이 필수적인 요소이며 식물생육에 선택적인 파장을 조사할 수 있는 LED와 재배조건을 정밀하게 제어할 수 있는 밀폐형 식물공장을 이용한 의료용 대마 생산에 대한 연구가 절실히 필요한 시점이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.477-480
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• 2022

반도체 성능 향상으로 신호를 전달하는 회로의 단위가 마이크로 미터에서 나노미터로 미세화되어 선폭(linewidth)이 점점 좁아지고 있다. 이러한 변화는 검출해야 할 불량의 크기가 작아지고, 정상 공정상태와 비정상 공정상태의 차이도 상대적으로 감소되어, 공정오차 및 공정조건의 허용범위가 축소되었음을 의미한다. 따라서 검출해야 할 이상징후 탐지가 더욱 어렵게 되어, 높은 정밀도와 해상도를 갖는 검사공정이 요구되고 있다. 이러한 이유로, 미세 공정변화를 파악할 수 있는 신규 검사 및 계측 공정이 추가되어 TAT(Turn-around Time)가 증가하게 되었고, 웨이퍼가 가공되어 완제품까지 도달하는데 필요한 공정시간이 증가하여 제조원가 상승의 원인으로 작용한다. 본 논문에서는 웨이퍼의 검계측 데이터가 아닌, 제조공정 과정에서 발생하는 다양한 센서 및 장비 데이터를 기반으로 웨이퍼 제조 결과가 양품인지 그렇지 않으면 불량인지 구별할 수 있는 가상계측 모델을 제안한다. 기계학습의 여러 알고리즘 중에서 다양한 장점을 갖는 XGBoost 알고리즘을 이용하여 예측모델을 구축하였고, 데이터 전처리(data-preprocessing), 주요변수 추출(feature selection), 모델 구축(model design), 모델 평가(model evaluation)의 순서로 연구를 수행하였다. 결과적으로 약 94% 이상의 정확성을 갖는 모형을 구축하는데 성공하였으나 더욱 높은 정확성을 확보하기 위해서는 반도체 공정과 관련된 Domain Knowledge 를 반영한 모델구축과 같은 추가적인 연구가 필요하다.

• Analytical Science and Technology
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• v.31 no.4
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• pp.149-160
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• 2018

A large number of functional living products are being produced for eco-friendly or health-promoting purposes. In the manufacturing process, such products could be adulterated with raw materials with high radioactivity, such as monazite and tourmaline. Thus, it is essential to manage raw materials and products closely related to the public living. For proper management, an accurate radioactivity data of the processed products are needed. Therefore, it is essential to develop a rapid and validated analytical method. In this study, the concentration of the radioactive $^{238}U$ and $^{232}Th$ in building materials (e.g., tile, cement, paint, wall paper, and gypsum board) and living products (e.g., health products, textiles, and minerals) were determined and compared by ED-XRF and ICP-MS. By comparing the results of both methods, we confirmed the applicability of the rapid screening and precise analysis of ED-XRF and ICP-MS. In addition, $^{238}U$ and $^{232}Th$ levels were relatively lower in building materials than in living products. Particularly, $^{232}Th$ content in 6 of 47 living products exceeded (maximum $8.2Bq{\cdot}g^{-1}$) the standard limit of $^{232}Th$ content in raw material ($1.0Bq{\cdot}g^{-1}$).

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.199-204
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• 2010

Members used for the Korean traditional joints have been processed by handicraft, especially with domestic red pine species. Dovetail joint is most commonly used in woodworking joinery and traditional horizontal and vertical connections. It is able to be processed much easier to cut by handicraft and machines. However, although it is processed straight forwards, it requires a high degree of accuracy to ensure a snug fit. Also, tenons and mortises must fit together with no gap between them so that the joint interlocks tightly. A few scientific studies on the dovetail joints have been conducted so far. For the effective applications of traditional joints and domestic plantation wood species, dovetail joints were assembled by larch glulam members processed by machine pre-cut. To identify the tensile properties of through dovetail joints, larch glulam with 150 150mm in cross section were prepared. Furthermore, various geometric parameters of dovetai joints such as width, length, and tenon angle, were surveyed. The ends in the mortise was cracked mainly at a low strength level in the control specimens without reinforcements. The maximum tensile strengths of reinforced specimens considering real connections such as capital joint and headpiece on a column, increasedby handicraft, especially with domestic red pine species. Dovetail joint is most commonly used in woodworking joinery and traditional horizontal and vertical connections. It is able to be processed much easier to cut by handicraft and machines. However, although it is processed straight forwards, it requires a high degree of accuracy to ensure a snug fit. Also, tenons and mortises must fit together with no gap between them so that the joint interlocks tightly. A few scientific studies on the dovetail joints have been conducted so far. For the effective applications of traditional joints and domestic plantation wood species, dovetail joints were assembled by larch glulam members processed by machine pre-cut. To identify the tensile properties of through dovetail joints, larch glulam with 150 150mm in cross section were prepared. Furthermore, various geometric parameters of dovetai joints such as width, length, and tenon angle, were surveyed. The ends in the mortise was cracked mainly at a low strength level in the control specimens without reinforcements. The maximum tensile strengths of reinforced specimens considering real connections such as capital joint and headpiece on a column, increased by two times with shear failures on the tenon than the control specimens. The maximum tensile strength was obtained in the specimen of 25 degrees, and no difference was observed in the changes of neck widths.

• Journal of Food Hygiene and Safety
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• v.33 no.6
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• pp.466-473
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• 2018

An analytical method of sodium polyacrylate in processed food products was developed and monitored by using size-exclusion chromatography. GF-7M HQ column and UV/VIS detector were selected based on peak shape and linearity. Flow rate, column oven temperature, and mobile phase were selected as 0.6 mL/min, $45^{\circ}C$, and 50 mM sodium phosphate buffer of pH 9.0, respectively. Samples for analysis of sodium polyacrylate were extracted with 50 mM sodium phosphate buffer of pH 7.0 for 3 hr at $20^{\circ}C$ and 150 rpm. Analytical method validation revealed proper selectivity and calibration curve was selected in the range of 50-500 mg/L, and correlation coefficient of calibration curve was more than 0.9985. Limit of detection of sodium polyacrylate was 10.95 mg/kg and limit of quantification was 33.19 mg/kg. Accuracy and coefficient of variation for sodium polyacrylate analysis was 99.6-127.6%, 3.0-8.3% for intra-day and 94.3-121.9%, 1.3-2.6% for inter-day, respectively. Sodium polyacrylate was detected in 40 samples among monitored 125 processed food products. Detected contents were less than 0.2%, limited by the Food Additives Code. Results suggest the established size-exclusion chromatography method could be used to analyze sodium polyacrylate in processed food products.

• Journal of Preventive Medicine and Public Health
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• v.24 no.1 s.33
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• pp.37-44
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• 1991

In the plywood manufacturing factory established in 1979, female 3 workers who had exposed to adhesives containing formaldehyde for more than 48 months of duration suffered from eye, nasal, oral, throat and skin irritation and dyspnea as chief complaints. The actual level of the exposure to formaldehyde were not estimated when the exposed workers started to have above symptoms. The environmental monitoring of workplace was measured on April 25, 1990, and the concentration of formaldehyde revealed 0.2 ppm, however the exhaustive ventilatory system was already installed at that time. Twenty six subjects from entire factory were examined by questionnaire, physical examination and spirometry, etc. on August 22, 1990. Significant difference was observed in symptoms and signs of nasal, oral and throat irritation between the exposed group with longer duration and that with short duration. When the exposed group with longer duration was compared to the group of nonexposed, symptoms and signs of nasal, oral, throat and skin irritaion, chest tightness and dullness were significantly increased in the former group. The results of the spirometric test showed that the forced vital capacity and the forced expiratory volume at 1 second were decreased among the exposed group with longer duration but not significant.

• Korean Journal of Optics and Photonics
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• v.23 no.1
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• pp.12-16
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• 2012

In the paper, we fabricated a Ni master with $45^{\circ}$-mirror structures for flexible waveguide fabrication. The flexible waveguide films with embedded $45^{\circ}$-angled mirrors at the waveguide ends were successfully fabricated using a UV-imprint process. Next, in order to enhance the reflectivity of the mirrors, Ni(3 nm)-Au(200 nm) bilayers were evaporated on the $45^{\circ}$-angled facets through a locally opened thin mask using an electron beam evaporator. We measured propagation loss, bending loss, mirror loss and bending reliability of the fabricated waveguide.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.3
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• pp.283-291
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• 2013

Rice varieties with suitable flour-making quality are required to promote rice processed-food industry and boost rice consumption in Korea. 'Namil (SA)-flo1' is an advanced mutant line with floury endosperm which shows good flour-making quality under dry-milling process. Genetic analysis was carried out to localize the chromosomal region responsible for the floury endosperm of 'Namil (SA)- flo1'. By using 94 F2 progenies, which were derived from 'Namil (SA)-flo1' ${\times}$ 'Milyang 23', floury grains percentage was investigated as phenotypic data, and genotyping was conducted with 54 SSR markers. Association analysis showed that the target genetic region for floury endosperm is on middle-low region of chromosome 5. Through further association analysis with increased number of SSR markers on chromosome 5, we found that genotypic variation in RM164 explains 79.7% of the variation in floury grains percentage of F2:3 seeds. The floury endosperm locus was localized on 17.7-20.7 Mbp region of chromosome 5 and will be further analyzed for fine mapping and gene identification.

• Korean Journal of Optics and Photonics
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• v.19 no.4
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• pp.287-293
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• 2008

The collimator which makes a collimated beam, is an essential instrument for assembly and evaluation of telescopes. Recently, the Cassegrain type collimator has been widely used for its compact size as the focal length of high resolution cameras becomes longer. However, this kind of collimator has a disadvantage in that the secondary mirror is a heat source which can degrade the evaluation accuracy for an IR camera system. In this paper, we present the fabrication and measurement process for an off-axis parabolic mirror with the physical diameter pf 1 m, effective diameter 930 mm, and the focal length 6 m. After four months of works we obtained the final surface wave-front error of 30.4 nm rms ($\lambda$/138, ${\lambda}=4.2\;{\mu}m$), which is capable of evaluation of an IR camera as well as a visible camera.