• Journal of the Korean Wood Science and Technology
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• 제52권2호
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• pp.101-117
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• 2024

The conversion characteristics of the major components of Liriodendron tulipifera were investigated during acid-catalyzed organosolv pretreatment. Glucan in L. tulipifera was slowly hydrolyzed, whereas xylan was rapidly hydrolyzed. Simultaneous hydrolysis and degradation of xylan and lignin occurred; however, after complete hydrolysis of xylan at higher temperatures, lignin remained and was not completely degraded or solubilized. These conversion characteristics influence the structural properties of glucan in L. tulipifera. Critical hydrolysis of the crystalline regions in glucan occurred along with rapid hydrolysis of the amorphous regions in xylan and lignin. Breakdown of internal lignin and xylan bonds, along with solubilization of lignin, causes destruction of the lignin-carbohydrate complex. Over a temperature of 160℃, the lignin that remained was coalesced, migrated, and re-deposited on the surface of pretreated solid residue, resulting in a drastic increase in the number and content of lignin droplets. From the results, the characteristic conversions of each constituent and the changes in the structural properties in L. tulipifera effectively improved enzymatic hydrolysis in the range of 140℃-150℃. Therefore, it can be concluded that significant changes in the biomass recalcitrance of L. tulipifera occurred during organosolv pretreatment.

• Tuberculosis and Respiratory Diseases
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• 제67권3호
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• pp.199-204
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• 2009

Background: To examine the recovery rate of nontuberculous mycobacteria (NTM) from respiratory specimens and the clinical course of NTM pulmonary disease at a 700-bed secondary hospital. Methods: This study analyzed the results of 843 acid-fast bacilli (AFB) culture-positive respiratory specimens from 650 subjects collected between May 2003 and April 2008. In addition, the clinical course of NTM pulmonary disease, diagnosed using criteria established by the American Thoracic Society, was examined. Results: There were 67 (7.9%) NTM isolates recovered from 52 (8.0%) subjects. Among the 535 AFB smear-positive specimens, 34 (6.3%) NTM isolates were recovered. There were 33 (10.7%) NTM isolates were recovered from 308 AFB smear-negative specimens. Of 52 subjects with isolated NTM, M. intracellulare was the most common species at 73.1% (n=33), followed by M. kansassi (n=7), M. abscessus (n=2), M. fortuitum (n=2), and M. avium (n=1). Sixteen (30.8%) patients had NTM pulmonary disease and the most common causative organism was M. intracellulare (n=14, 87.5%). Of these, 6 cases attained negative conversion in culture, 4 cases failed to attain negative conversion because of poor cooperation or expiration from complicated underlying lung disease, and 5 cases were transferred to a higher-grade hospital. Conclusion: The recovery rate of NTM from respiratory specimens was relatively low and the most common species was M. intracellulare. Patients with NTM pulmonary disease showed variable clinical outcomes.

• 전기전자학회논문지
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• 제24권1호
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• pp.33-39
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• 2020

본 논문에서는 타이어의 물리적인 요소 중 하나인 압력정보를 이용해서 자동차의 하중 표출이 가능한 타이어 공기압 측정 기술을 사용한 차량의 적재중량 측정시스템 설계 기법을 제안한다. 제안된 기법은 하중 및 진동에 의한 노이즈 보정, 기체유량 보정, 데이터 믹서, 중량 환산 등의 4가지 과정으로 구성된다. 하중 및 진동에 의한 노이즈 보정에서는 외부충격 및 차량이 주행 중 발생하는 진동 등에 의해 타이어의 내부 압력이 상승하는 노이즈를 제거한다. 기체유량 보정 과정에서는 하중 및 진동에 의한 노이즈 보정 과정을 거친 데이터에 대하여 지면의 온도상승에 의해 타이어의 내부 압력이 상승하는 노이즈를 제거한다. 데이터 믹서 과정에서는 화물적재 시 타이어에 수직으로 전달이 되어 타이어의 압력변화에 따른 공차, 중차, 만차에 대한 하중과 압력 등을 분류하게 된다. 중량 환산 과정에서는 하중 및 진동에 의한 노이즈 보정 및 기체유량 보정을 거친 데이터를 사용하여 중량 환산 알고리즘을 통해 중량으로 표출된다. 중량 환산 알고리즘은 하중과 압력변화에 대한 선형 함수의 기울기인 중량 환산 Factor를 구하여 중량을 환산한다. 본 논문에서 제안된 타이어 공기압 측정 기술을 사용한 차량의 적재중량 측정 시스템의 정밀도를 평가하기 위해 자체적으로 테스트 베드를 구축하여 평가하였다. 하중 및 진동에 의한 노이즈 보정 결과와 기체 유량 데이터 보정 결과는 신뢰성 있는 결과를 나타내었다. 또한 중량 정밀도 반복 실험도 국내 업체 기준치인 90% 보다 우수한 중량 정밀도를 나타내었다.

• IMMUNE NETWORK
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• 제2권2호
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• pp.79-85
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• 2002

Background: In contrast to evidences of Ig H chain receptor editing in transformed cell lines and transgenic mouse models, there has been no direct evidence that this phenomenon occurs in human developing B cells. Methods: $V_HDJ_H$ rearrangements were obtained from genomic DNA of individual $IgM^-$ B cells from liver and $IgM^+B$ cells from bone marrow of 18 wk of gestation human fetus by PCR amplification and direct sequencing. Results: We found three examples of H chain receptor editing from $IgM^+$ and $IgM^-human$ fetal B cells. Two types of $V_H$ replacements were identified. The first involved $V_H$ hybrid formation, in which part of a $V_H$ gene from the initial VDJ rearrangement is replaced by part of an upstream $V_H$ gene at the site of cryptic RSS. The second involved a gene conversion like replacement of CDR2, in which another $V_H$ gene donated a portion of its CDR2 sequence to the initial VDJ rearrangement. Conclusion: These data provide evidence of receptor editing at the H chain loci in developing human B cells, and also the first evidence of a gene conversion event in human Ig genes.

• Tuberculosis and Respiratory Diseases
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• 제80권1호
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• pp.27-34
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• 2017

Background: A sputum culture is the most reliable indicator of the infectiousness of pulmonary tuberculosis (PTB); however, a spontaneous sputum specimen may not be suitable. The aim of this study was to evaluate the infectious period in patients with non-drug-resistant (DR) PTB receiving adequate standard chemotherapy, using induced sputum (IS) specimens. Methods: We evaluated the duration of infectiousness of PTB using a retrospective cohort design. Results: Among the 35 patients with PTB, 22 were smear-positive. The rates of IS culture positivity from baseline to the sixth week of anti-tuberculosis medication in the smear-positive PTB group were 100%, 100%, 91%, 73%, 36%, and 18%, respectively. For smear-positive PTB cases, the median time of conversion to culture negativity was 35.0 days (range, 28.0-42.0 days). In the smear-negative PTB group (n=13), the weekly rates of positive IS culture were 100%, 77%, 39%, 8%, 0%, and 0%, respectively, and the median time to conversion to culture-negative was 21.0 days (range, 17.5-28.0 days). Conclusion: The infectiousness of PTB, under adequate therapy, may persist longer than previously reported, even in patients with non-DR PTB.

• Tuberculosis and Respiratory Diseases
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• 제77권2호
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• pp.73-80
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• 2014

Background: Low levels of serum vitamin D is associated with several lung diseases. The production and activation of matrix metalloproteinases (MMPs) may play an important role in the pathogenesis of emphysema. The aim of the current study therefore is to investigate if vitamin D modulates the expression and activation of MMP-2 and MMP-9 in human lung fibroblasts (HFL-1) cells. Methods: HFL-1 cells were cast into three-dimensional collagen gels and stimulated with or without interleukin-$1{\beta}$ (IL-$1{\beta}$) in the presence or absence of 100 nM 25-hydroxyvitamin D (25(OH)D) or 1,25-dihydroxyvitamin D ($1,25(OH)_2D$) for 48 hours. Trypsin was then added into the culture medium in order to activate MMPs. To investigate the activity of MMP-2 and MMP-9, gelatin zymography was performed. The expression of the tissue inhibitor of metalloproteinase (TIMP-1, TIMP-2) was measured by enzyme-linked immunosorbent assay. Expression of MMP-9 mRNA and TIMP-1, TIMP-2 mRNA was quantified by real time reverse transcription polymerase chain reaction. Results: IL-$1{\beta}$ significantly stimulated MMP-9 production and mRNA expression. Trypsin converted latent MMP-2 and MMP-9 into their active forms of MMP-2 (66 kDa) and MMP-9 (82 kDa) within 24 hours. This conversion was significantly inhibited by 25(OH)D (100 nM) and $1,25(OH)_2D$ (100 nM). The expression of MMP-9 mRNA was also significantly inhibited by 25(OH)D and $1,25(OH)_2D$. Conclusion: Vitamin D, 25(OH)D, and $1,25(OH)_2D$ play a role in regulating human lung fibroblast functions in wound repair and tissue remodeling through not only inhibiting IL-$1{\beta}$ stimulated MMP-9 production and conversion to its active form but also inhibiting IL-$1{\beta}$ inhibition on TIMP-1 and TIMP-2 production.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.237.1-237.1
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• 2010

Recent developments such as concern over global warming, depletion of fossil fuels and increase in energy demands by the increasing world population has eventually lead to mass production of electricity using renewable sources. Ocean contains energy in form of thermal energy and mechanical energy: thermal energy from solar radiation and mechanical energy from the waves and tides. The current paper looks at generating power using waves. The primary objective of the present study is to maximize the primary energy conversion (first stage conversion) of the base model by making some design changes. The model entire consisted of a numerical wave tank and the turbine section. The turbine section had three components; front guide nozzle, augmentation channel and the rear chamber. The augmentation channel further consisted of a front nozzle, rear nozzle and an internal fluid region representing the turbine housing. Different front guide nozzle configuration and rear chamber design were studied. As mentioned, a numerical wave tank was utilized to generate waves of desired properties and later the turbine section was integrated. The waves in the numerical wave tank were generated by a piston type wave maker which was located at the wave tank inlet. The inlet which was modeled as a plate wall which moved sinusoidally with the general function, $x=asin{\omega}t$. In addition to primary energy conversion, observation of flow characteristics, pressure and the velocity in the augmentation channel, rear chamber as well as the front guide nozzle are presented in the paper. The analysis was performed using the commercial code of the ANSYS-CFX. The base model recorded water power of 29.9 W. After making the changes, the best model obtained water power of 37.1 W which represents an increase of approximately 24% in water power and primary energy conversion.

• 한국실내디자인학회논문집
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• 제22권5호
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• pp.51-59
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• 2013

This study aimed to present the possibilities that a variety of conversions can be made in terms of the spatial function through the situation analysis and in-depth case studies, focusing on the cases of the conversion of historic buildings. Literature analysis and case analysis technique were conducted as the research methods. For the literature analysis, the researcher selected 105 cases of conversion-type buildings by recombining and reanalyzing them to space functional changes; the SPSS PC+ 18.0 program was used as the analysis tool to conduct a frequency analysis and cross analysis. In-depth analysis was conducted to investigate the overview of the architecture, building history, spatial functional changes, space program, conservation value, and the conserved parts by selecting 9 cases in Korean and foreign countries that have been recently converted through literature analysis and the results of the study were as follows. 1) As a result of analyzing the changes in function, the highest percentage of the cases was conversion into the cultural function (63.8%). 2) There were cases for conversion into the commercial function, business function, accommodation function and educational function besides cultural function. 3) As a result of spatial program, the attempts to increase the utilization of the building generally by applying the complex space with more than two functions could be seen. 4) The buildings with historical and architectural value were conserved most of the outer wall and some portion of internal parts; the buildings with symbolic value were renovated largely, while preserving symbolic parts; and the buildings with practical value were renovated in a way that maintains the structural parts while changing the interior space to be suitable for their function.

• Tuberculosis and Respiratory Diseases
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• 제57권2호
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• pp.180-182
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• 2004

항결핵제중 isoniazid는 nicotinic acid의 합성을 방해하여 pellagra의 발생을 초래할 수 있다. 저자들은 70세 여자 환자에서 폐결핵 치료중 isoniazid에 의해 발생한 pellagra 1례를 경험하였기에 문헌고찰과 함께 보고하는 바이다.

• 공업화학
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• 제5권3호
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• pp.385-394
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• 1994

세공분포가 서로 다른 두 종류(KHT, X-5)의 ${\gamma}$-알루미나 pellet에 아황산가스를 흡착 제거시킬 경우 반응이 진행되면서 각각의 세공벽에 반응생성층이 형성되어 반응속도 상수($K_v$), 세공률(${\varepsilon}_p$), 유효내부 확산계수($D_e$)의 변화와 세공반경이 줄어들어 세공막힘 현상이 일어나게 된다. 이들 영향을 고려하여 세공분포를 이용한 Random pore model로 최적반응온도 $450^{\circ}C$에서 산화구리의 각 담지농도(4, 6, 8, l0 wt%)와 아황산가스의 농도(1000, 2000ppm)에 대한 전환율을 수학적 모델로부터 계산하였다. 산화구리의 담지농도가 증가할수록 세공내의 유효반응 표면적과 세공률의 감소, 내부확산저항의 증가, 미세세공의 세공막힘 현상으로 전환율은 감소하였다. 총괄 전환율은 ${\gamma}$-알루미나 pallet의 표면 국부 전환율에 크게 의존하였으며 산화구리의 담지농도가 낮고 아황산가스의 농도가 클수록 증가하였다. 반응기에 유입되는 아황산가스의 유속은 반응초기 CuO의 전환율에 영향을 주었고 세공분포가 발달하여 세공율이 큰 ${\gamma}$-알루미나 pellet일수록 전환율은 높게 나타났다.