• 대한영양사협회학술지
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• 제13권4호
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• pp.389-406
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• 2007

This study was conducted to estimate the safety level of non-cooking and cooking processed foods to propose the sanitary management of foods donated to foodbanks. The time and temperature were measured and the microbial levels of aerobic plate counts (APC), coliforms, E. coli, Salmonella spp., S. aureus, B. cereus, and E. coli O157:H7 were analyzed on ten food items donated to seven foodbanks. The amount of cooked foods donated to each foodbank was about 10 to 40 servings. All foodbanks hired a supervisor and had at least one refrigerator/freezer and one temperature-controlled vehicle, but only four foodbanks had the separate offices to manage the foodbank operation. The flow of donated foods was gone through the steps; production, meal service and holding at donator, collection by foodbank, transport (or holding after transport) and distribution to recipients. After production, the levels of APC of both non-cooking and cooking processed foods were complied with the standards by Ministry of Education & Human Resources Development, and were not increased till distribution. Only the level of coliforms in dried squid & cucumber salad (1.5×$10^3$ CFU/g) was not met the standards. E. coli and other pathogens were not detected in all tested samples. The microbial levels of delivery vessels and work tables were satisfactory, but the APC levels of two of four tested serving tables (6.9×$10^3$ and 5.3×$10^3$ CFU/100$cm^2$) and the coliforms level of one (1.1×$10^3$ CFU/100$cm^2$) were over the standards. The air-borne microflora level in serving room was estimated as satisfactory. It took about 3.0 to 6.5 hours from after-production to distribution and the temperatures of donated foods were exposed mostly to temperature danger zone, which had a high potential of microbial growth. These results imply that a checklist to monitor time and temperature in each step should be provided and the employees involving foodbank operation should be properly educated to ensure the safety of donated foods.

• The Journal of Advanced Prosthodontics
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• 제12권1호
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• pp.22-32
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• 2020

PURPOSE. The aim of this study was to evaluate the microshear bond strength (µSBS) of four computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three different surface treatment protocols. MATERIALS AND METHODS. Four different CAD/CAM blocks were used in this study: (1) flexible hybrid ceramic (FHC), (2) resin nanoceramic (RNC), (c) polymer infiltrated ceramic network (PICN) and (4) feldspar ceramic (FC). All groups were further divided into four subgroups according to surface treatment: control, hydrofluoric acid etching (HF), air-borne particle abrasion with aluminum oxide (AlO), and tribochemical silica coating (TSC). After surface treatments, silane was applied to half of the specimens. Then, a silane-containing universal adhesive was applied, and specimens were repaired with a composite, Next, µSBS test was performed. Additional specimens were examined with a contact profilometer and scanning electron microscopy. The data were analyzed with ANOVA and Tukey tests. RESULTS. The findings revealed that silane application yielded higher µSBS values (P<.05). All surface treatments were showed a significant increase in µSBS values compared to the control (P<.05). For FHC and RNC, the most influential treatments were AlO and TSC (P<.05). CONCLUSION. Surface treatment is mandatory when the silane is not preferred, but the best bond strength values were obtained with the combination of surface treatment and silane application. HF provides improved bond strength when the ceramic content of material increases, whereas AlO and TSC gives improved bond strength when the composite content of material increases.

• 대한전자공학회논문지SP
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• 제48권1호
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• pp.8-15
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• 2011

본 논문에서는 지상라이다에서 획득한 3차원 점군데이터로부터 구조물을 모델링하는 알고리듬을 제안한다. 지상라이다 점군 데이터는 항공라이다의 경우와 달리 목표 구조물의 크기와 비슷한 다양한 장애물이 존재하고 데이터의 밀도, 거리 등의 특성이 다르기 때문에 항공라이다에서 사용된 기존의 알고리듬을 그대로 적용하기가 곤란하다. 제안한 방법에서는 색상정보와 호프변환을 이용하여 구조물을 추출하는 기법을 기반으로 주어진 필드데이터를 여러 개의 클러스터로 구분한다. 클러스터 데이터의 우선순위에 따라서 Delaunay triangulation 기법을 차례대로 적용하여 모델링을 수행한다. 제안한 방법은 클러스터 단위로 모델링을 진행하므로 잡음에 의한 영향을 최소화할 수 있으며 사용자가 원하는 개수만큼의 클러스터를 선택함으로써 모델링의 수준을 대화식으로 조정할 수 있다는 장점이 있다.

• 한국환경보건학회지
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• 제36권3호
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• pp.191-198
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• 2010

The aim of this study was to determine the concentrations of air-borne microorganisms (bacteria, fungi, gram negative bacteria (GNB), endotoxins, and respirable suspended particles (RSPs), and their correlation with environmental parameters (temperature, humidity, and carbon dioxide levels) in duck houses. The mean concentrations of bacteria, fungi, and GNB were very high (> $10^6\;CFU/m^3$), and endotoxin levels exceeded $10^3\;EU/m^3$. Among the various work stages, in the task of receiving ducks, bacteria were $6.2{\times}10^6;CFU/m^3$, and GNB were $5.4{\times}10^6\;CFU/m^3$, while RSPs levels were $397.6\;{\mu}g/m^3$ and endotoxin levels were $47.2{\times}10^3\;EU/m^3$ in the task of dividing the ducks, and fungi were $4.9{\times}10^6\;CFU/m^3$ in the task of shipping the ducks. The concentrations of RSPs and endotoxins were significantly higher in tasks involving greater movement of ducks in the house, relative to tasks involving little movement of ducks (p<0.05). Further, with progression in growth of the ducks, the concentrations of bacteria, GNB, endotoxins, and RSPs were significantly increased. There was significant correlation between levels of GNB with bacteria (r=0.75) and fungi (r=0.86), endotoxins with RSPs (r=0.75), bacteria with fungi (r=0.39), and carbon dioxide with RSPs (r=0.38), bacteria (r=0.33), and endotoxins (r=0.31). These results suggest considerable respiratory hazard for farmers in these environments.

• Structural Engineering and Mechanics
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• 제42권6호
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• pp.831-847
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• 2012

Impact from water-borne debris during tsunami and flood events pose a potential threat to structures. Debris impact forces specified by current codes and standards are based on rigid body dynamics, leading to forces that are dependent on total debris mass. However, shipping containers and other debris are unlikely to be rigid compared to the walls, columns and other structures that they impact. The application of a simple one-dimensional model to obtain impact force magnitude and duration, based on acoustic wave propagation in a flexible projectile, is explored. The focus herein is on in-air impact. Based on small-scale experiments, the applicability of the model to predict actual impact forces is investigated. The tests show that the force and duration are reasonably well represented by the simple model, but they also show how actual impact differs from the ideal model. A more detailed three-dimensional finite element model is also developed to understand more clearly the physical phenomena involved in the experimental tests. The tests and the FE results reveal important characteristics of actual impact, knowledge of which can be used to guide larger scale experiments and detailed modeling. The one-dimensional model is extended to consider water-driven debris as well. When fluid is used to propel the 1-D model, an estimate of the 'added mass' effect is possible. In this extended model the debris impact force depends on the wave propagation in the two media, and the conditions under which the fluid increases the impact force are discussed.

• 한국항공우주학회지
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• 제37권8호
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• pp.737-743
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• 2009

본 연구는 Tabu Search를 이용하여 LHP의 최적설계를 진행하는 방법과 절차 및 결과를 제시하고자 한다. 최적설계의 목적은 항공기에 탑재된 리튬이온 전지의 작동온도 조건을 만족하면서 LHP의 중량을 최소화시키는 것이다. 전지는 고에너지 밀도의 특성으로 항공기에 장착된 고에너지 레이저의 동력원으로 사용되는 것으로 가정되었다. 해석은 Steady state analysis model에 기초하였으며 메타모델로 근사화하였다. 최적화 결과로 Tabu Search는 유전알고리듬 등 다른 비 구배기반 최적화 방법에 비해 비교적 적은 계산 시간을 소요하면서도 전역해를 보장하였으나 난수에 의해 초기해를 바꾸어 가면서 최적화를 여러 번 시도해야 하는 단점이 있었다. 그리고 최적화 과정을 통해 기 발표된 LHP와 동일한 성능을 가지면서도 경량화된 LHP를 얻을 수 있었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.727-731
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• 2003

ASTER image has some advantages for classification such as 15 spectral bands and 15m ${\sim}$ 90m spatial resolution. However, in the classification using general remote sensing image, shadow areas are often classified into water area. It is very difficult to divide shadow and water. Because reflectance characteristics of water is similar to characteristics of shadow. Many land cover items are consisted in one pixel which is 15m spatial resolution. Nowadays, very high resolution satellite image (IKONOS, Quick Bird) and Digital Surface Model (DSM) by air borne laser scanner can also be used. In this study, mixed pixel analysis of ASTER image has carried out using IKONOS image and DSM. For mixed pixel analysis, high accurated geometric correction was required. Image matching method was applied for generating GCP datasets. IKONOS image was rectified by affine transform. After that, one pixel in ASTER image should be compared with corresponded 15×15 pixel in IKONOS image. Then, training dataset were generated for mixed pixel analysis using visual interpretation of IKONOS image. Finally, classification will be carried out based on Linear Mixture Model. Shadow extraction might be succeeded by the classification. The extracted shadow area was validated using shadow image which generated from 1m${\sim}$2m spatial resolution DSM. The result showed 17.2% error was occurred in mixed pixel. It might be limitation of ASTER image for shadow extraction because of 8bit quantization data.

• 한국측량학회지
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• 제25권4호
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• pp.347-354
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• 2007

최근 대형 포털 업체들이 3차원 공간 영상 서비스를 선보이면서 3차원 가상 도시모델에 대한 수요가 증가하고 있고, 이에 따라 업체들은 경쟁적으로 보다 높은 해상도 및 정확도의 서비스를 제공하고자 노력하고 있다. 건물 모델은 3차원 도시모델의 구성요소 중 가장 많은 개체수를 차지하며, 각 개체별로 다양한 형태와 텍스쳐 정보를 가지는 특성으로 인해 현실적인 모델 제작은 시간이 많이 소요되고 제작비용도 높다. 이런 문제는 광범위 지역의 3차원 도시모델 서비스 및 업데이트를 제약하는 가장 큰 요소이다. 따라서 본 연구에서는 수치지도의 건물 레이어를 기반으로 생성된 건물 기하학적 모형에 항공사진 또는 위성영상과 같은 공간영상을 활용하여 빠르고 경제적으로 텍스쳐 매핑을 수행하여 실감 3차원 건물 모델을 생성할 수 있는 방법을 제안하였다. 실험결과 제안된 방법은 여러 가지 항공사진 및 위성영상을 이용한 빠르고 경제적인 3차원 빌딩 모델 생성에 효과적임을 알 수 있었다.

• Journal of Species Research
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• 제8권2호
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• pp.197-214
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• 2019

The taxonomic hierarchy of the phylum Proteobacteria was assessed, after which the isolation and classification state of Proteobacteria species with valid names for Korean indigenous isolates were studied. The hierarchical taxonomic system of the phylum Proteobacteria began in 1809 when the genus Polyangium was first reported and has been generally adopted from 2001 based on the road map of Bergey's Manual of Systematic Bacteriology. Until February 2018, the phylum Proteobacteria consisted of eight classes, 44 orders, 120 families, and more than 1,000 genera. Proteobacteria species isolated from various environments in Korea have been reported since 1999, and 644 species have been approved as of February 2018. In this study, all novel Proteobacteria species from Korean environments were affiliated with four classes, 25 orders, 65 families, and 261 genera. A total of 304 species belonged to the class Alphaproteobacteria, 257 species to the class Gammaproteobacteria, 82 species to the class Betaproteobacteria, and one species to the class Epsilonproteobacteria. The predominant orders were Rhodobacterales, Sphingomonadales, Burkholderiales, Lysobacterales and Alteromonadales. The most diverse and greatest number of novel Proteobacteria species were isolated from marine environments. Proteobacteria species were isolated from the whole territory of Korea, with especially large numbers from the regions of Chungnam/Daejeon, Gyeonggi/Seoul/Incheon, and Jeonnam/Gwangju. Most Halomonadaceae species isolated from Korean fermented foods and solar salterns were halophilic or halotolerant. Air-borne members of the genera Microvirga, Methylobacterium, and Massilia had common characteristics in terms of G+C content, major respiratory quinones, and major polar lipids.

• Restorative Dentistry and Endodontics
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• 제46권4호
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• pp.54.1-54.10
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• 2021

Objectives: The purpose of this study was to quantify phase transformation after hydrofluoric acid (HF) etching at various concentrations on the surface of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), and to evaluate changes in bonding strength before and after thermal cycling. Materials and Methods: A group whose Y-TZP surface was treated with tribochemical silica abrasion (TS) was used as the control. Y-TZP specimens from each experimental group were etched with 5%, 10%, 20%, and 40% HF solutions at room temperature for 10 minutes. First, to quantify the phase transformation, Y-TZP specimens (n = 5) treated with TS, 5%, 10%, 20% and 40% HF solutions were subjected to X-ray diffraction. Second, to evaluate the change in bond strength before and after thermal cycling, zirconia primer and MDP-containing resin cement were sequentially applied to the Y-TZP specimen. After 5,000 thermal cycles for half of the Y-TZP specimens, shear bond strength was measured for all experimental groups (n = 10). Results: The monoclinic phase content in the 40% HF-treated group was higher than that of the 5%, 10%, and 20% HF-treated groups, but lower than that of TS-treated group (p < 0.05). The 40% HF-treated group showed significantly higher bonding strength than the TS, 5%, and 10% HF-treated groups, even after thermal cycling (p < 0.05). Conclusions: Through this experiment, the group treated with SiO₂ containing air-borne abrasion on the Y-TZP surface showed higher phase transformation and higher reduction in bonding strength after thermal cycling compared to the group treated with high concentration HF.