• 펄프종이기술
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• 제39권3호
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• pp.1-11
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• 2007

To evaluate the quality of waste paper used for the manufacture of linerboard, the types of papers and foreign materials in compressed waste paper currently used were investigated. The recycled fibers were obtained from printing paper, newspaper, wrapping paper, white coated paperboard and corrugated container. Their fibers were observed by using a microscope, and the mechanical properties of the recycled papers manufactured from the recycled fibers were investigated. The compressed wastepaper was composed of 54% paperboard, 20% printing paper, and 20% newsprint. The content of foreign materials was about 4%, showing higher contents compared to 1% of foreign substances provided by Korea paper manufacturers' association. The types of foreign materials were various, which include vinyls, plastics, metals, woods, styrofoams, and cloths. Sound fibers were generally observed in the recycled fibers of printing papers and wrapping paper. The recycled fibers of white coated board, corrugated container and newsprint showed to be generally damaged. The whiteness of each recycled fiber were highly affected by pulp bleaching and ink-particle mixing conditions. The values of breaking length and burst index were lower than those for corrugating medium and liner board specified in KS. Although the anatomical characteristics of recycled fibers varied, their strengths appeared to be similar. This result may be explained by the use of non-deinked fiber.

• 천문학회보
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• 제46권1호
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• pp.49.5-50
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• 2021

We report the optical follow-up observations of three long γ-ray burst events, GRB 201020A, GRB 201103B and GRB 210104A by the network of telescopes in the SomangNet project. We show light curves, color evolution and SED evolution, and fit them to a single power law function to derive decay index and compare their properties with other long GRBs samples. Also, we show a good observational example that 0.4-1m class telescopes in SomangNet have potential to catch dim light from high red shift object (R>22 mag) by deep imaging. In conclusion, we found that three GRBs have optical afterglow properties of long GRB and our results are consistent with the reports of high energy analysis.

• 농업과학연구
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• 제26권1호
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• pp.21-30
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• 1999

본 연구는 골판지고지의 가장 중요한 물성인 강도적 성질을 증대시키기 위하여 섬유의 전처리 방법으로서 Hobart mixer를 사용하여 섬유 내부의 결합제거 및 섬유표면에 Microcompression을 형성하여 개질처리 하였으며, 4가지 방법의 고해방법(Valley beater, Kady mill, Impact refining)을 채택하여 골판지고지의 최적고해 방법을 찾는데 그 목적을 두고 이 연구를 수행하였다. 그 결과는 다음과 같다. 1. 섬유장감소를 적게 유발하는 고해방법으로는 Kady mill과 PFI mill의 고해방법 이었으며 고해시 Curl을 펴주는 고해방법을 Kady mell과 Valley beater의 고해방법이 적절하였다. 2. 열단장은 Valley beating의 고해방법에 의하여 강도가 가장 많이 증가되었으며 인열강도는 가장 많이 감소하였다. 섬유전처리를 한 Comp-1과 Comp-2는 고해방식과 상관없이 열단장을 전체적으로 약 10% 증대시켰다. 3. 인열강도는 Comp-1, Comp-2의 전처리방법과 PFI mill 고해로 증대할수 있었다. 4. 파열강도는 Comp-1, Comp-2의 전처리방법과 Valley beater 고해로 증대할수 있었다. 5. 인열강도를 우지한채로 열단장을 가장 높이는 방법은 섬유전처리 방식인 Comp-1이나 Comp-2를 사용하여 Valley beating을 이용하는 방법으로 판단되었다.

• 공업화학
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• 제7권2호
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• pp.315-320
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• 1996

본 실험에서는 보류향상제의 첨가량과 중질 탄산칼슘 첨가량에 따른 탄산칼슘 보류량(회분함량)을 조사하였으며, 동일 회분량에서 종이의 기계적 광학적 특성을 비교하였다. 각 보류시스템 모두 보류향상제 첨가량을 증가시키면 중질 탄산칼슘(입자평균직경 $3.2{\mu}m$) 보류, 즉 종이의 회분량은 증가한다. 이 경우 보류향상제와 중질 탄산칼슘 첨가량을 조절하여 이미 예정된 회분량이 함유된 종이를 초지할 수 있다. 종이의 인장지수, 파열지수, 인열지수 및 내부결합강도는 종이의 회분량이 증가됨에 따라 직선적으로 감소한다. 특히 동일 회분량에서 비교하면, 콤포질 시스템에 의한 종이에서 제반 강도가 높고, 듀알 폴리머 시스템에서는 강도가 낮다. 불투명도는 회분량 증가에 따라 함께 증가하며, 하이드로콜 시스템에서 가장 높고 역시 듀알 폴리머에서 가장 낮다. 동일 불투명도에서 종이의 강도는 콤포질, 하이드로콜, 듀알 폴리머 시스템 순으로 감소한다. 그러나 보류향상제의 우열을 판단하기 위해서는 충전제의 보류량과 종이의 강도 이외에도 적정 생산조건 및 적정 공정조건과 같은 여러 가지 다른 요인들도 고려되어야 한다.

• The Korean Journal of Physiology and Pharmacology
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• 제4권3호
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• pp.219-226
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• 2000

In order to elucidate the role of platelet activating factor (PAF) in the acute lung injury induced by endotoxin (ETX), activities of phospholipase A2, lyso PAF acetyltransferase and oxidative stress by neutrophilic respiratory burst were probed in the present study. To induce acute lung injury, $100\;{\mu}g$ of E.coli ETX (type 0127; B8) was instilled directly into the tracheae of Sprague-Dawley rats. Five hours after the ETX instillation, induction of acute lung injury was confirmed by lung leak index and protein contents in the bronchoalveolar lavage (BAL) fluid. At the same time, lung phospholipase A2 (PLA2) activity and expression of group I and II secretory type PLA2 were examined. In these acutely injured rats, ketotifen fumarate, known as lyso PAF acetyltransferase inhibitor and mepacrine were administered to examine the role of PAF in the pathogenesis of the acute lung injury. To know the effect of the ETX in the synthesis of the PAF in the lungs, lyso PAF acetyltransferase activity and PAF content in the lungs were measured after treatments of ETX, ketotifen fumarate and mepacrine. In addition, the role of neutrophils causing the oxidative stress after ETX was examined by measuring lung myeloperoxidase (MPO) and enumerating neutrophils in the BAL fluid. To confirm the oxidative stress in the lungs, pulmonary contents of malondialdehyde (MDA) were measured. After instillation of the ETX in the lungs, lung leak index increased dramatically (p＜0.001), whereas mepacrine and ketotifen decreased the lung leak index significantly (p＜0.001). Lung PLA2 activity also increased (p＜0.001) after ETX treatment compared with control, which was reversed by mepacrine and ketotifen (p＜0.001). In the examination of expression of group I and II secretory PLA2, mRNA synthesis of the group II PLA2 was enhanced by ETX treatment, whereas ketotifen and WEB 2086, the PAF receptor antagonist, decreased the expression. The activity of the lysoPAF acetyltransferase increased (p＜0.001) after treatment of ETX, which implies the increased synthesis of PAF by the remodelling of lysoPAF in the lungs. Consequently, the contents of the PAF in the lungs were increased by ETX compared with control (p＜0.001), while mepacrine (p＜0.001) and ketotifen (p＜0.01) decreased the synthesis of the PAF in the lungs of ETX treated rats. The infiltration of the neutrophils was confirmed by measuring and enumerating lung MPO and the neutrophils in the BAL fluid respectively. Compared with control, ETX increased lung MPO and number of neutrophils in BAL significantly (p＜0.001) whereas mepacrine and ketotifen decrerased number of neutrophils (p＜0.001) and MPO (p＜0.05, p＜0.001, respectively). The lung MDA contents were also increased (p＜0.001) by ETX treatment, but treatment with mepacrine (p＜0.001) and ketotifen (p＜0.01) decreased the lung MDA contents. Collectively, we conclude that ETX increases PLA2 activity, and that the subsequently increased production of PAF was ensued by the remodelling of the lyso PAF resulting in tissue injury by means of oxidative stress in the lungs.

• Tuberculosis and Respiratory Diseases
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• 제63권6호
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• pp.497-506
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• 2007

연구배경: 급성호흡곤란증후군의 병인론에 관여하는 PAF의 역할이 다양하고 중요하므로 본 연구에서는 PAF의 또 다른 작용의 가능성, 즉 $cPLA_2$의 활성화(retrograde activation of $cPLA_2$ by PAF)의 가능성을 검사하고자 하였다. 즉, $cPLA_2$의 활성화에 따른 염증성 지질분자의 생성이 산소기의 생성과정을 증폭시키고 이 때 생성된 PAF가 역으로 $cPLA_2$를 활성화시키는지를 확인하기 위하여 본 연구는 고안되었다. 방 법: 흰쥐에서 급성폐손상을 유도하기 위하여 $5{\mu}g$의 PAF를 0.5 ml의 0.25% bovine serum albumin 용액과 혼합한 뒤 기도 내로 직접 분무하거나 0.5 ml의 4.5 mM의 과산화수소를 기도 내로 분무하였다. 대조군의 경우는 0.5 ml의 생리적 식염수를 기도 내로 분무하였다. 5 시간 후에 단백누출지수 측정, 폐장의 MPO 활성도 측정, 폐포 세척액 내의 호중구 산정, CINC 측정, NBT 및 cytochrome-c 환원검사를 시행하였다. 또한 폐장 및 호중구에 서의 $cPLA_2$ 활성도의 측정 및 광학현미경과 전자현미경을 이용하여 형태학적 관찰을 시행하였다. 결 과: PAF투여 후 단백누출지수, MPO, BAL내의 호중 구의 수 및 CINC의 농도가 대조군에 비하여 유의하게 증가하였다. NBT및 cytochrome-c환원검사의 결과 PAF는 호중구의 respiratory burst를 현저히 증가시키고, 분리된 사람의 호중구에서도 산소기의 생성을 현저히 증가시켰 다. 동시에 PAF는 분리된 호중구 및 폐장의 $cPLA_2$의 활성도도 증가 시켰다. 폐장 내로 투여한 과산화수소는 폐장의 $cPLA_2$활성도를 대조군에 비하여 현저히 증가시켰다. 결 론: $cPLA_2$의 활성화에 따라 생성된 PAF는 호중구의 산소기 생성을 증가시켜 폐장 내의 산화성스트레스를 유발하고 동시에 이때 생성된 산화기는 $cPLA_2$를 활성화시키며 PAF 또한 $cPLA_2$의 활성도를 증가시켜 PAF가 급성호흡 곤란증후군의 병인론에 관여하는 것으로 생각된다.

• Tuberculosis and Respiratory Diseases
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• 제71권2호
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• pp.97-105
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• 2011

Background: It was hypothesized that the immunomodulating effects of moxifloxacin contribute to ameliorate oleic acid (OA)-induced acute lung injury (ALI) by suppression of cytosolic phospholipase A2 (cPLA2). This was based on observations from experiments on rats associated with neutrophilic respiratory burst, cPLA2 activity, and expressions of cPLA2, $TNF{\alpha}$, and COX-II in the lung. Methods: ALI was induced by intravenous injection of OA in male Sprague-Dawley rats. Five hours after OA injection, protein content in bronchoalveolar lavage (BAL), lung myeloperoxidase (MPO) activity, and numbers of BAL neutrophils were measured. As an index of oxidative stress-induced lung injury, the content of malondialdehyde (MDA) in lung tissues was also determined. Lung histology, immunohistochemistry and determination of activity of cPLA2 in lung tissues were carried out. In addition, Western blotting of $TNF{\alpha}$ and COX-II in lung tissues was performed. Results: The accumulation of neutrophils in the lungs was observed after OA injection. BAL protein was increased along with neutrophilic infiltration and migration by OA. Moxifloxacin decreased all of these parameters of ALI and ameliorated ALI histologically. The increased malondialdehyde (MDA) in the lung by OA was also decreased by moxifloxacin. Moxifloxacin not only suppressed cPLA2 expression in the lungs and neutrophils but also decreased cPLA2 activity in lung tissues of rats given OA. The enhanced expressions of $TNF{\alpha}$ and COX-2 in the lung tissues of rats given OA were also suppressed by moxifloxacin. Conclusion: Moxifloxacin inhibited cPLA2 and down-regulated $TNF{\alpha}$ and COX-2 in the lungs of rats given OA, which resulted in the attenuation of inflammatory lung injury.

• 한국농림기상학회지
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• 제6권1호
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• pp.49-60
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• 2004

Northern Gyeonggi Province(NGP), consisting of 3 counties, is the northernmost region in South Korea adjacent to the de-militarized zone with North Korea. To supplement insufficient spatial coverage of official climate data and climate atlases based on those data, high-resolution digital climate models(DCM) were prepared to support weather- related activities of residents in NGP Monthly climate data from 51 synoptic stations across both North and South Korea were collected for 1981-2000. A digital elevation model(DEM) for this region with 30m cell spacing was used with the climate data for spatially interpolating daily maximum and minimum temperatures, solar irradiance, and precipitation based on relevant topoclimatological models. For daily minimum temperature, a spatial interpolation scheme accommodating the potential influences of cold air accumulation and the temperature inversion was used. For daily maximum temperature estimation, a spatial interpolation model loaded with the overheating index was used. Daily solar irradiances over sloping surfaces were estimated from nearby synoptic station data weighted by potential relative radiation, which is the hourly sum of relative solar intensity. Precipitation was assumed to increase with the difference between virtual terrain elevation and the DEM multiplied by an observed rate. Validations were carried out by installing an observation network specifically for making comparisons with the spatially estimated temperature pattern. Freezing risk in January was estimated for major fruit tree species based on the DCMs under the recurrence intervals of 10, 30, and 100 years, respectively. Frost risks at bud-burst and blossom of tree flowers were also estimated for the same resolution as the DCMs.

• Smart Structures and Systems
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• 제2권2호
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• pp.101-113
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• 2006

Structural health monitoring results obtained with the electro-mechanical (E/M) impedance techniqueand Lamb wave transmission methods during fatigue crack propagation of an Arcan specimen instrumented with piezoelectric wafer active sensors (PWAS) are presented. The specimen was subjected in mixed-mode fatigue loading and a crack was propagated in stages. At each stage, an image of the crack and the location of the crack tip were recorded and the PWAS readings were taken. Hence, the crack-growth in the specimen could be correlated with the PWAS readings. The E/M impedance signature was recorded in the 100 - 500 kHz frequency range. The Lamb-wave transmission method used the pitch-catch approach with a 3-count sine tone burst of 474 kHz transmitted and received between various PWAS pairs. Fatigue loading was applied to initiate and propagate the crack damage of controlled magnitude. As damage progressed, the E/M impedance signatures and the waveforms received by receivers were recorded at predetermined intervals and compared. Data analysis indicated that both the E/M impedance signatures and the Lamb-wave transmission signatures are modified by the crack progression. Damage index values were observed to increase as the crack damage increases. These experiments demonstrated that the use of PWAS in conjunction with the E/M impedance and the Lamb-wave transmission is a potentially powerful tool for crack damage detection and monitoring in structural elements.

• Journal of the Korean Wood Science and Technology
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• 제30권2호
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• pp.134-143
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• 2002

본 시험은 외발뜨기 한지와 쌍발뜨기 한지의 물리적 특성과 도침이 지질에 어떠한 영향을 미치고 있는지를 구명하고자 검증된 토착한지와 오늘날 전통식으로 제조한 한지, 그리고 개량 한지를 대상으로 했다. 외발뜨기 한지는 치우치지 않는 강도적 특성 때문에 실제 사용할 때, 강하고 질기며 잘 해어지지 않는 종이임을 알 수 있었다. 이처럼 질기다고 느껴지는 것은 좋은 원료와 토착식 제법으로 여러 장 겹쳐서 절대적인 강도를 향상 시켰기 때문이었다. 그러나 상대적 강도인 지수비교에서는 기타 한지와 큰 차이가 없었다. 도침은 내절도를 두드러지게 향상시키며 열단장과 파열지수를 높이는 역할을 했다. 특히 열단장(인장강도)의 향상을 가져왔다. 섬유 배향성을 고려하지 않고 초지한 외발뜨기 한지를 쌍발뜨기 한지와 비교해 보면 가로·세로의 강도 차이가 약간 적다는 것 외에 특별히 뛰어난 점이 없다는 것을 알 수 있었다.