미세조류 활성도 평가를 위한 Photosynthesis and Respiration (P&R) Analyzer 분석조건 최적화

허재희,심태석,황선진 한국물환경학회 2021 한국물환경학회지 Vol.37 No.6

Photosynthesis and respiration rate of microalgae are important factors during advanced wastewater treatment research using microalgae, There are several equipments and measurement methods for measuring photosynthesis and respiration, with different challenges that occur during pretreatment and stabilization of the analysis process. Therefore, in this study, for accurate Photosynthesis and Respiration (P&R) analyzer measurement, the analysis process was divided into pre-processing, DO stabilization, and analysis stages and each was optimized to enable accurate evaluation. For this purpose, the effect of DO saturation of the sample on P&R analysis, DO stabilization according to the degassing flow rate, and photoinhibition of the OD level on photosynthesis was investigated. Based on our study results, when DO was supersaturated, photosynthetic efficiency decreased due to photorespiration, making it inappropriate as a P&R sample. In addition, 0.5 L-N2/min level was the optimal nitrogen degassing flow rate for DO desaturation. The inhibition of photosynthetic efficiency by self-shading caused by the increase in OD was observed from OD 2.0, a nd i t was found that P & R analysis i s preferably p erformed o n samples with O D less t han 2.0. In addition, based on the above three optimization results , an optimized P&R Analyzer instruction for accurate P&R analysis was also presented.

La0.7Sr0.3MnO3의 합성, 특성 평가 및 전자기파 흡수 특성

허재희,강영민 대한금속·재료학회 2023 JOURNAL- KOREAN INSTITUTE OF METALS AND MATERIALS Vol.61 No.3

Perovskite manganese La0.7Sr0.3MnO3 (LSMO) powders were prepared by sol-gel synthesis andcalcination in the temperature (T) range of 500~1200 oC and their structures and electromagnetic (EM)wave absorption properties were investigated. X-ray diffraction (XRD) analysis revealed that thecrystalline perovskite phase can be formed at T ≥ 600 oC. The average grain size was ~15 nm at thecalcination temperature (Tcal) = 600 oC and it increased to ~1 μm when Tcal increased up to 1200 oC. MHcurves of the samples showed soft magnetic behaviors for all the crystallized samples, and the valueof saturation magnetization increased with increasing Tcal. The real and imaginary parts of permittivitiesand permeabilities were measured on LSMO powder-epoxy (10 wt%) composites using a network vectoranalyzer in the frequency range of 100 MHz ≤ f ≤ 18GHz. The complex permittivities (ε', ε") increasedsignificantly in samples calcined above 800 oC because the concentration of free electrons increased, dueto the LSMO's unique magnetotransport effect, as the crystallinity and the MS value increasedsignificantly. As the Tcal increased, the height of the μ' and μ" spectra also gradually increased. The largevalues of ε', ε" of the LSMO-epoxy are dominant factors in the EM wave absorption characteristics, andit showed good absorption characteristics when it had a thickness of 1.5 mm or less at a frequency of 12GHz or higher. At the same time, it also exhibited EM wave shielding ability by reflection in the severalGHz band.

M2+, 3+ (M = Mn3+, Zn2+, Ni2+)이 치환된 Sr3Co2Fe24O41 hexaferrite 복합체의 전자기파 흡수 특성

허재희,강영민 대한금속·재료학회 2024 대한금속·재료학회지 Vol.62 No.8

Mn, Zn, Ni-substituted Z-type hexaferrites, Sr3Co2Fe24O41 (Sr3Co2Fe24-xMnxO41, Sr3Co2-yZnyFe24O41,Sr3Co1-zNizZnFe24O41), were prepared by sol-gel synthesis processes and their high-frequency magnetic,dielectric and electromagnetic (EM) wave absorption characteristics were investigated. Substituting Mn forFe by x = 0.5 maintained the single-phase Z phase while shifting the  , μ″ spectra towards lower frequencies. Substituting Zn for Co by y = 1.0 resulted in the single-phase Z phase and effectively shifted the  , μ″ spectratowards lower frequencies. Additionally, substituting Ni by z = 0.5, 1.0 gradually shifted the  , μ″ spectratowards higher frequencies. The Sr3Co2Fe24O41 with a single Z-type hexaferrite phase and epoxy (10 wt.%)composite showed strong ferromagnetic resonance (FMR) at 3.05 GHz and exhibited primary and secondarystrong EM wave absorption characteristics at the thicknesses where impedance matching occurred near theFMR frequency and at frequencies higher than this. Substitution of Mn and Zn tended to decrease the FMRfrequency, while substitution of Ni tended to increase it. The samples with substituted compositions alsoshowed changes in the primary and secondary strong EM wave absorption frequency regions, depending onthe FMR frequency changes. They demonstrated excellent EM wave absorption performance with the absolutevalue of the minimum reflection loss (RLmin) ranging from 42 to 58 dB. The FMR-tunable Z-type hexaferriteis a promising EM wave absorption material that can modulate EM wave absorption characteristics by cationsubstitution in in L-S-band (1~4 GHz) and X-band (8~12 GHz) ranges.

특발성 척추측만증 환자에서의 3차원적 재구성을 이용한 척추경의 크기 측정

허재희,안면환 영남대학교 의과대학 2004 Yeungnam University Journal of Medicine Vol.21 No.1

특발성 척추측만증 환자에서 3차원적인 재구성을 이용한 관상면에서 척추경의 폭을 측정하는 것이 오차를 줄일 수 있는 방법이고 척추경 나사못의 삽입 시 척추경의 크기를 술 전에 측정한 후 그 값의 최대치보다 작은 최대 크기의 원추형 나사못을 삽입하는 것이 안전한 방법이라 사료된다. 척추경 나사못을 삽입할 시에는 척추경의 모양이 원주 형태가 아닌 낙루형태나 신장 형태 등 추체마다의 다양한 모양을 고려하여 나사못 크기와 삽입 방법에 세심한 주의가 필요할 것으로 사료된다. Background: This study was conducted to analyze the height and width of the pedicle of the upper and lower levels on the concave and the convex sides. In addition, we checked for the appropriate pedicle screw size which could be screwed in without complications. Materials and Methods: Taking a simple AP radiography in a standing position, 99 vertebrae on the major curve with the possibility of 3-D reconstruction were analyzed after checking the CT in a supine position of 22 idiopathic scoliosis. We measured Cobb's angle from a simple radiograph, and measured the size of the isthmus by the Inner Space 3-D Editor after 3-D reconstruction with the Inner Space 3-D program in the DICOM file transformed from CT image. We then analyzed the size of pedicles of the upper and lower levels on the concave and the convex sides by measuring the height and width of the pedicle. Results: All pedicles on the concave side were smaller than those on the convex side. Their size increased as the measurement moved from the upper to lower vertebra, except for the upper thoracic vertebra. When the width of the pedicle through 3-D reconstruction was compared with the narrowest width of the pedicle measured by using CT, the width of the pedicles through 3-D reconstruction was statistically smaller (P<0.01). Most of the pedicles were tear-drop or kidney shaped rather than cylindrical. Conclusion: These results suggest that the use of the coronal plane through 3-D reconstruction would be necessary for an accurate measurement of the size of the pedicle. It is important to pay careful attention to the screw size and the screwing method considering the pedicle shape through 3-D reconstruction.

La0.7Sr0.3MnO3의 합성, 특성 평가 및 전자기파 흡수 특성

허재희,강영민 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.3

Perovskite manganese La0.7Sr0.3MnO3 (LSMO) powders were prepared by sol-gel synthesis andcalcination in the temperature (T) range of 500~1200 oC and their structures and electromagnetic (EM)wave absorption properties were investigated. X-ray diffraction (XRD) analysis revealed that thecrystalline perovskite phase can be formed at T ≥ 600 oC. The average grain size was ~15 nm at thecalcination temperature (Tcal) = 600 oC and it increased to ~1 μm when Tcal increased up to 1200 oC. MHcurves of the samples showed soft magnetic behaviors for all the crystallized samples, and the valueof saturation magnetization increased with increasing Tcal. The real and imaginary parts of permittivitiesand permeabilities were measured on LSMO powder-epoxy (10 wt%) composites using a network vectoranalyzer in the frequency range of 100 MHz ≤ f ≤ 18GHz. The complex permittivities (ε', ε") increasedsignificantly in samples calcined above 800 oC because the concentration of free electrons increased, dueto the LSMO's unique magnetotransport effect, as the crystallinity and the MS value increasedsignificantly. As the Tcal increased, the height of the μ' and μ" spectra also gradually increased. The largevalues of ε', ε" of the LSMO-epoxy are dominant factors in the EM wave absorption characteristics, andit showed good absorption characteristics when it had a thickness of 1.5 mm or less at a frequency of 12GHz or higher. At the same time, it also exhibited EM wave shielding ability by reflection in the severalGHz band.

언어 차이에 따른 갈색과 분홍의 색채 범주화

허재희(Heo, Jae Hee),박영경(Park, Yung Kyung) 한국디자인문화학회 2017 한국디자인문화학회지 Vol.23 No.3

갈색과 분홍은 2차색으로써 1차색에 비해 떠오르는 색이 명확하지 않으며, 어떤 색들이 혼합되는가에 대한 연상하기 어렵다. 언어적 측면에 있어 갈색과 분홍은 색의 특징을 설명하기 위해서 많은 수식어가 필요하고, 산업체에서 주로 사용하는 색명은 한국어인 갈색과 분홍에 비해 영어인 Brown(브라운)과 Pink(핑크)의 비중이 상당히 크다. 이에 본 연구에서는 언어적 차이에 따라 갈색과 Brown(브라운), 분홍과 Pink(핑크)가 어떻게 다르게 범주화되는가를 알아봄으로써, 색채계획의 효율성과 인식의 명확성을 높이기 위한 목적이 있다. 본 연구의 실험도구로서 실험1에서는 한국색채표준의 2.5YR 4/8(갈색), 2.5YR 6/4(탁한 주황), 10RP 4/2(회자주), 7.5R 7/8(분홍), 5RP 5/14(밝은자주), 5RP 8/6(연한 자줏빛 분홍)의 6가지 색 샘플을 사용하였고, 실험2에서는 한국색채표준 갈색과 분홍의 계통색명을 가지고 있는 색들과 그보다 넓은 범위에 걸쳐 갈색과 분홍으로 인식되는 색들을 포함한 464개의 샘플을 사용하였다. 실험 환경에 있어서 오프라인 실험의 경우, 샘플의 미세한 인쇄오차가 우려되어 동일한 생활조도 및 디스플레이환경에서 한국색채표준 디지털색채팔레트를 활용해 온라인으로 실험을 진행하였다. 연구방법에 있어서 실험1은 선택지 없이 색 샘플을 보고 명명하는 방식으로 진행되었고, 실험2는 명목척도를 활용하여 7가지의 항목에 대하여 색들이 범주화되는 것을 보았다. 실험 및 연구결과는 다음과 같다. 분홍에 비해 갈색을 명명함에 있어 더 많은 수식어를 사용하면서, 갈색에 대한 인식이 더 불명확하다는 것을 알 수 있었다. 또한 여성이 갈색으로 인식하는 색의 색상범위는 2.5R–2.5Y, Brown(브라운)은 5RP-2.5Y였고, 갈색이 Brown(브라운)과 비교하여 R계열에 분포하며 채도가 높은 특징을 보였다. 여성과 다르게 남성이 갈색으로 인식하는 색의 색상범위는 7.5R-2.5Y이고, Brown(브라운)은 10RP-10YR로 여성과 차이가 있었으며, 채도에서는 여성과 동일한 결과를 보였지만 명도에 있어서 여성에 비해 더 넓은 범주를 가지고 있었다. 여성이 분홍으로 인식하는 색의 색상범위는 10P-7.5YR, Pink(핑크)는 5RP-10RP로 분홍의 색상범위가 Pink(핑크)의 범위보다 더 넓었고, 채도는 Pink(핑크)가 더 높게 나타남을 알 수 있었다. 남성이 분홍으로 인식하는 색의 색상범위는 2.5RP-10R, Pink(핑크)는 5RP-10RP로 여성과 차이가 있었고, 색조에 있어서는 동일했다. 범주화가 불명확한 색의 비율은 여성보다 남성이 더 높았으며, 여성이 색을 인지하는데 상대적으로 범주화가 명확하게 이루어졌음을 알 수 있었다. 본 연구를 통해 갈색과 분홍을 다양하게 사용하는 산업체에서 언어차이에 따른 사람들의 인식을 고려한 색명을 대상에 적용하여, 대상과 색에 대한 명확성을 높이고 색채계획의 효율성이 높아지기를 기대한다. Brown and Pink are secondary colors and it is hard to imagine what colors are made by mixing. In terms of language, Brown and Pink need a lot of modifiers in order to explain the characteristics of color, and the color names more used in various industries are Brown and Pink. In this study, it is aimed to improve the efficiency and perception of the color plan by understanding how the Galsek(Brown of Korean Language), Brown, Bunhong(Pink of Korean Language) and Pink categorize differently according to the linguistic difference. As experimental tools of this study, in Experiment 1, there were 6 colors of 2.5YR 4/8 (Brown), 2.5YR 6/4 (Dull Orange), 10RP 4/2 (Grayish Purple), 7.5R 7/8 (Pink), 5RP 5/14 (Light Purple), 5RP 8/6 (Light Purplish Pink) which were based on Korean Color Standards were used. In Experiment 2, 464 samples which were also based on Korean Color Standards were used, including the colors having Brown and Pink system color names and the colors recognized as Brown and Pink over a broader range. Also, in case of off-line experiment, since the fine print error of the sample is concerned, the experiment was conducted online using the Korean color standard digital color palette in the same living illumination and display environment. In the case of off-line in the experimental environment, since the fine printing error of the sample is concerned, the experiment was conducted online using the Korean Standard Digital Color Palette in the same living illumination and display environment. Experiment 1 was conducted by looking at the 6 color samples and writing the name of the colors freely without choice. Experiment 2 used the nominal scale to see how the colors were categorized for the seven items. The experimental results are as follows. Using the more modifiers in naming the brown than the pink, people can see that the perception of the brown is more unclear. The range of color recognized by the woman as Galsek is 2.5R-2.5Y, Brown is 5RP-2.5Y, and Galsek is distributed in the R series as compared to Brown. The range of color recognized by the males as Galsek was 7.5R-2.5Y and that of Brown was 10RP-10YR, which was the same as that of the woman in the saturation, but it was broader than that of the woman in the lightness. The range of colors recognized by the woman as Bunhong is 10P-7.5YR, and that of Pink was 5RP-10RP, and the color range of Bunhong is broader than the range of Pink. The range of color recognized by the man as Bunhong was 2.5RP-10R, and that of Pink was 5RP-10RP. The proportion of unclear color categorization was higher in males than in females, and the categorization was more clear than in that females recognized color. Through this study, it is expected that the industry which uses various colors of brown and pink will apply the color name considering the people’s recognition according to the language difference to the object, to improve the clarity of the object and color and the efficiency of the color plan.

텍스트 분류의 성능 향상을 위한 나이브 베이즈 응용 기법 비교 연구

허재희 ( Jae-hee Heo ),박은영 ( Eun-young Park ),박영호 ( Young-ho Park ) 한국정보처리학회 2015 한국정보처리학회 학술대회논문집 Vol.22 No.1

텍스트를 분류해내는 일이 점점 중요해지고 있는 현 시점에서 기계학습은 다른 기법들보다도 가장 효과적인 성능을 드러낸다. 그 중에서도 특히 나이브 베이즈 분류기는 간결하고 효율적으로 알려진 기계학습 모델 중에 하나이다. 본 논문은 보다 효과적인 텍스트 분류를 위해 나이브 베이즈의 기법들을 응용 및 개선하고자 한 기존의 연구들을 소개하고, 이를 분석하고자 한다.

갈색으로 인식되는 색의 범위와 순위에 대한 연구

허재희(JaeHee Heo),박영경(YungKyung Park) 한국색채학회 2016 한국색채학회 학술대회 Vol.2016 No.11

갈색은 다른 색으로 대체할 수 없는 갈색만의 이미지를 가지고 있고 산업 전반에 걸쳐서 다양하게 사용되고 있음에도 불구하고, 다른 색에 비해 떠오르는 색이 명확하지 않으며 어떤 색이 혼합되어 만들어지는지 연상하기 어려운 성향을 띈다. 이에 따라 본 연구에서는 이론에 기초한 갈색과 사람들이 인식하는 갈색간의 차이를 비교분석함으로써 실제 사람들이 인식하는 갈색의 범위를 정립함과 동시에 갈색 내에서도 색상 및 색조와 관련하여 사람들이 어떤 색을 더 갈색으로 인식하는지를 알아봄으로써, 갈색을 활용한 색채계획에 효율성을 높이고 사람들의 인식 속에 갈색에 대한 명확성을 높이데 목적이 있다. 설문은 3차례에 걸쳐 진행하였고 갈색으로 인식되는 범위, 갈색으로 인식되는 순위, BROWN과 갈색이라는 언어적 차이에서 오는 색상 및 색조 차이에 대한 설문 결과를 분석하였다. 그 결과, KS기준 사람들이 갈색으로 인식하는 색의 범위는 5RP부터 7.5Y까지였고, 가장 갈색으로 느끼는 색은 KS 2.5 YR 3/6(진한 갈색)이었으며 전체적으로 R보다 YR계열의 색을 더 갈색으로 인식하였다. 또한 붉은 느낌의 채도 높은 색들을 갈색으로 인식하였고, 상대적으로 채도가 낮으며 어두운 색조를 띄는 색들을 BROWN이라고 인식하였다.

호염기성 미세조류 Arthrospira platensis의 폐수처리 적용을 위한 종특이성 평가

이수현,허재희,황선진 한국물환경학회 2022 한국물환경학회지 Vol.38 No.6

Since the efficiency of wastewater treatment using microalgae differs depending on the metabolic characteristics of the species, it is important to understand the characteristics of target algae prior to the application in wastewater treatment. In this study, for the application of Arthrospira platensis to wastewater treatment, which is a filamentous alkaliphilic cyanobacteria, basic species specificity was identified and the possibility of application to wastewater treatment was investigated. As a result of the species specificity investigation, the specific growth rate between pH 7.0 and 11.0 showed the highest value near pH 9 at 0.25/day. The reason for the relatively low growth(0.08/day) at pH 11 was thought to be the CA(carbonic anhydrase) enzyme that is involved in carbon fixation during photosynthesis has the highest activity at pH 8.0 to 9.0, and at pH 11, CA activity was relatively low. In addition, A. platensis showed optimal growth at 400 PPFD(photosynthetic photon flux density) and 30℃, and this means that cyanobacteria such as A. platensis have a larger number of PS-I(photosystem I) than that of PS-II(photosystem II). It was speculated that it was because higher light intensity and temperature were required to sufficiently generate electrons to transfer to PS-I. Regarding the applicability of A. platensis, it was suggested that if a system using the synergistic effect of co-culture of A. platensis and bacteria was developed, a more efficient system would be possible. And different from single cocci, filamentous A. platensis expected to have a positive impact on harvesting, which is very important in the latter part of the wastewater treatment process.

안정화작전 간 대드론 체계 운용방안 적용 연구

김선웅,허재희 한국방위산업진흥회 2024 國防과 技術 Vol.- No.540