• 대한의용생체공학회:의공학회지
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• 제43권3호
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• pp.136-146
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• 2022

In this study, it is intended to provide basic data that can help develop a cardiovascular simulator for performance evaluation of pulse wave detectors by identifying the development status of domestic and overseas cardiovascular simulators. A total of 119 papers were selected by excluding duplicate literature, gray literature, and literature not related to a cardiovascular simulator. Based on the selected literature, the research trend of cardiovascular simulators was analyzed. As a result of analyzing the purpose of the study, most of the simulators were developed to evaluate the hemodynamic properties of artificial hearts and valves. In addition, it was used for simulation evaluation or hemodynamic studies such as pulse wave studies. As a result of analyzing configurations of the simulators, a heart most often consisted of only one left ventricle. For blood vessels, the Windkessel model was most often constructed using chambers and valves. In most studies, blood was reproduced by mixing glycerin and water to reproduce both density and viscosity. In addition, as a result of analysis from the perspective of medical device performance evaluation, simulators for evaluating artificial heart and artificial valves have been studied a lot, whereas simulators for blood pressure, pulse wave, and blood flow devices have been relatively insignificant. Based on the review results, we suggested considerations when developing a simulator for performance evaluations of a pulse wave detector.

• 한국농림기상학회지
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• 제24권2호
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• pp.78-82
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• 2022

생물계절은 작물의 발달 시기를 결정하며, 생육기 온도에 의해 크게 영향을 받는다. 과정 기반 모델(PBM)에서 엽면적은 생물계절 및 형태 모듈의 결합에 의해 동적으로 시뮬레이션된다. 따라서 잎 발달 속도 또는 최종 잎 수의 예측은 전체 작물 모델의 성능에 영향을 주게 된다. 기온에 따른 잎 축적 속도 결정을 위한 데이터는 SPAR 챔버로부터 수집되었다. 온도의 함수로서 발달 속도를 설명하기 위해 베타 분포 함수(Yan and Hunt(1999)에 의해 제안됨)가 사용되었으며, 최적온도와 임계온도는 각각 26.0℃와 35.3℃로 추정되었다. 모델 추정치는 기온 모델에 생장기의 일 평균 기온을 입력하여 얻은 양파 잎의 일별 증가량을 누적한 결과이며, 모델 평가를 위해 온도구배하우스에서 관찰된 양파 잎의 누적 개수를 모델 추정치와 비교하였다. 본 연구에서 잎 수 추정 모델의 결정계수(R²)와 RMSE 값은 각각 0.95와 0.89였다.

• 적정기술학회지
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• 제6권2호
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• pp.256-270
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• 2020

세계적인 전염병의 유행하에서 의료시스템의 붕괴는 시민사회의 자발적인 참여와 새로운 방식의 대응 방식이 나타나고 있다. 이는 보건 위기의 최전선에서 즉시 활용이 가능한 필수적 대응기술로, 적정기술이 더이상 중간기술로 개발도상국뿐 아니라 보건 시스템이 붕괴된 모든 시민 사회의 위기를 극복할 수 있는 기술로서의 역할을 보여주고 있다. 본 Part 2에서는 음압실 및 인공호흡기등 의료용 기구, 진단칩 및 진단기술등과 같이 COVID-19하에서 붕괴된 의료 위기 하에서 신속한 대응책으로 준비되고 있는 의료 및 보건분야에 대한 사례들을 적정기술의 테두리안에서 소개하고자 한다. 기존의 다국적 대기업과 공적인 인증등으로 인한 장벽으로 접근하기 어려웠던 분야에 과학기술자들의 자발적인 참여로 대중화되고 있음을 사례로 소개한다. 최근 사회혁신등에서 제기되고 있는 다양한 오픈과학기술 운동을 통해서, 과학자들과 공학자들이 이러한 질병의 대유행 상황에서, 사회에 소외된 계층의 피해를 최소화하여 사회적, 계층적 붕괴를 막기위한 재정의된 적정기술의 역할등을 설명하고자 한다.

• 대한본초학회지
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• 제28권4호
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• pp.63-69
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• 2013

Objectives : The purpose of present study was to investigate the vasorelaxant activities and mechanisms of action of the ethanol extract of P. yedoensis leaf (PYL) on isolated rat aortic rings. Methods : Dried P. yedoensis leaves were extracted 3 times with 100% ethanol for 3 h in a reflux apparatus. Isolated rat aortic rings were suspended in organ chambers containing 10 ml Krebs-Henseleit (K-H) solution. The rings were maintained at $37^{\circ}C$ and aerated with a mixture of 95% $O_2$ and 5% $CO_2$. Changes in their tension were recorded via isometric transducers connected to a data acquisition system. Results : PYL relaxed the contraction of aortic rings induced by phenylephrine (PE, 1 ${\mu}M$) or KCl (60 mM) in a concentration dependent manner. However, the vasorelaxant effects of PYL on endothelium-denuded aortic rings were lower than endothelium-intact aortic rings. And the vasorelaxant effects of PYL on endothelium-intact aortic rings were reduced by pre-treatment with $N{\omega}$-Nitro-L-arginine methyl ester (10 ${\mu}M$), methylene blue (10 ${\mu}M$), 1-H-[1,2,4]-oxadiazolo-[4,3-${\alpha}$]-quinoxalin-1-one (10 ${\mu}M$), tetraethylammonium (5 mM). In addition, PYL inhibited the contraction induced by extracellular $Ca^{2+}$ in endothelium-denuded aortic rings pre-contracted by PE or KCl in $Ca^{2+}$-free K-H solution. Conclusions : These results suggest that PYL exerts its vasorelaxant effects via the activation of Nitric Oxide (NO) formation by means of L-arginine and NO-cGMP pathways and via the blockage of receptor operated calcium channels, voltage dependent calcium channels and calcium-activated potassium channels.

• 한국환경농학회지
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• 제40권4호
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• pp.366-372
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• 2021

BACKGROUND: Ammonia is known as a precursor to fine particulate matter, and according to CAPSS, annual ammonia emissions in the agricultural sector were 249,777 tons as of 2018, accounting for about 79.0% of Korea's total ammonia emissions. In particular, ammonia emissions from agricultural land increased by 19,566 tons (10.2%) compared to the previous year. The Ministry of Environment is setting emission statistics using the ammonia emission coefficient developed in Korea in 2008, but researchers in the agricultural field regard it as a coefficient that does not reflect the reality of Korea's agricultural environment. Accordingly, in order to develop ammonia emission coefficients from the cultivation of apples and pears, Korea's representative fruit type, test agricultural land was set in Iksan, Jeollabuk-do. METHODS AND RESULTS: This study attempted to obtain the ammonia emission coefficient by the treatment of the composite fertilizer (N-P₂O₅-K₂O=12-7-9), and the flux was measured using a dynamic flow-through chamber method. As for the chamber, a total of 12 chambers were installed repeatedly in 4 zones and used to develop emission coefficients. Using compound fertilizers during fruit tree cultivation, the ammonia emission coefficient was evaluated as 10.4 kg NH3/ton for pears and 15.3 kg NH₃/ton for apples. The reason why the ammonia emission coefficient according to the use of composite fertilizers was calculated higher for apple cultivation is believed to be due to the relatively high pH concentration of apple orchard soil. CONCLUSION(S): This study may provide basic data for upgrading the ammonia emission coefficient when using composite fertilizers in agricultural land. In the future, it might be necessary to upgrade the calculation of emissions through the development of ammonia and fine particulate matter emission coefficients considering the agricultural environment of Korea.

• 인간식물환경학회지
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• 제23권6호
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• pp.637-646
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• 2020

Background and objective: The main objective of this study is to measure the amount of particulate matter (PM) reduction under different characteristics of leaves in 18 different species of indoor plants. Methods: First, a particular amount of PM was added to the glass chambers (0.9×0.86×1.3 m) containing the indoor plant (height = 40 ± 20 cm), and the PM concentration were measured at 2-hour intervals. The experiment with the same conditions was conducted in the empty chamber as the control plot. Results: The range of PM reduction per unit leaf area of 18 species of experimental plants was 3.3-286.2 ㎍·m^-2 leaf, total leaf area was 1,123-4,270 cm², and leaf thickness was 0.14-0.80 mm and leaf size 2.27-234.47 cm². As time passed, the concentration of PM decreased more in the chamber with plants than in the empty chamber. Among the 18 indoor plants, the ones with the greatest reduction in PM2.5 in 2 hours and 4 hours of exposure to PM2.5 were Pachira aquatica and Dieffenbachia amoena. As the exposure time of PM increased, the efficiency of reducing PM2.5 was higher in plants with medium-sized leaves than plants with large or small leaves. The effect of reducing PM2.5 was higher in linear leaves than round or lobed leaves. Plants with high total leaf area did not have advantage in reducing PM because the leaves were relatively small and there were many overlapping parts between leaves. In the correlation between leaf characteristics and PM 2.5 reductions, all leaf area and leaf thickness showed a negative and leaf size showed a positive correlation with PM reduction. Conclusion: The PM reduction effect of plants with medium-sized leaves and long linear leaves was relatively high. Moreover, plants with a large total leaf area without overlapping leaves will have advantaged in reducing PM. Plants are effective in reducing PM, and leaf characteristics are an important factor that affects PM reduction.

• Animal Bioscience
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• 제35권5호
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• pp.690-697
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• 2022

Objective: This study aimed to evaluate the effect of the ad libitum and restricted feeding regimen on fasting heat production (FHP) and body composition. Methods: Twelve Hubbard broilers breeders were selected with the same body weight and submitted in two feeding regimes: Restricted (T1) with feed intake of 150 g/bird/d and ad libitum (T2). The birds were randomly distributed on the treatments in two runs with three replications per treatment (per run). The birds were adapted to the feed regimens for ten days. After that, they were allocated in the open-circuit chambers and kept for three days for adaptation. On the last day, oxygen consumption (VO₂) and carbon dioxide production (VCO₂) were measured by 30 h under fasting. The respiratory quotient (RQ) was calculated as the VCO₂/VO₂ ratio, and the heat production (HP) was obtained using the Brower equation (1985). The FHP was estimated throughout the plateau of HP 12 hours after the feed deprivation. The body composition was analyzed by dual-energy X-ray absorptiometry scanning at the end of each period. Data were analyzed for one-way analysis of variance using the Minitab software. Results: The daily feed intake was 30 g higher to T2 (p<0.01) than the T1. Also, the birds of the T2 had significatively (p<0.05) more oxygen consumption (+3.1 L/kg^0.75/d) and CO₂ production (+2.2 L/kg^0.75/d). That resulted in a higher FHP 359±14 kJ/kg^0.75/d for T2 than T1 296±17.23 kJ/kg^0.75/d. In contrast, the RQ was not different between treatments, with an average of 0.77 for the fasting condition. In addition, protein and fat composition were not affected by the treatment, while a tendency (p<0.1) was shown to higher bone mineral content on the T1. Conclusion: The birds under ad libitum feeding had a higher maintenance energy requirement but their body composition was not affected compared to restricted feeding.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2935-2940
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• 2023

A polystyrene phantom was developed following the guidance of the International Atomic Energy Association (IAEA) for gamma knife (GK) quality assurance. Its performance was assessed by measuring the absorbed dose rate to water and dose distributions. The phantom was made of polystyrene, which has an electron density (1.0156) similar to that of water. The phantom included one outer phantom and four inner phantoms. Two inner phantoms held PTW T31010 and Exradin A16 ion chambers. One inner phantom held a film in the XY plane of the Leksell coordinate system, and another inner phantom held a film in the YZ or ZX planes. The absorbed dose rate to water and beam profiles of the machine-specific reference (msr) field, namely, the 16 mm collimator field of a GK Perfexion^TM or Icon^TM, were measured at seven GK sites. The measured results were compared to those of an IAEA-recommended solid water (SW) phantom. The radius of the polystyrene phantom was determined to be 7.88 cm by converting the electron density of the plastic, considering a water depth of 8 g/cm². The absorbed dose rates to water measured in both phantoms differed from the treatment planning program by less than 1.1%. Before msr correction, the PTW T31010 dose rates (PTW Freiberg GmbH, New York, NY, USA) in the polystyrene phantom were 0.70 (0.29)% higher on average than those in the SW phantom. The Exradin A16 (Standard Imaging, Middleton, WI, USA) dose rates were 0.76 (0.32)% higher in the polystyrene phantom. After msr correction factors were applied, there were no statistically significant differences in the A16 dose rates measured in the two phantoms; however, the T31010 dose rates were 0.72 (0.29)% higher in the polystyrene phantom. When the full widths at half maximum and penumbras of the msr field were compared, no significant differences between the two phantoms were observed, except for the penumbra in the Y-axis. However, the difference in the penumbra was smaller than variations among different sites. A polystyrene phantom developed for gamma knife dosimetry showed dosimetric performance comparable to that of a commercial SW phantom. In addition to its cost effectiveness, the polystyrene phantom removes air space around the detector. Additional simulations of the msr correction factors of the polystyrene phantom should be performed.

• 한국초지조사료학회지
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• 제14권3호
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• pp.186-194
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• 1994

넓은 잎 벌로랑이의 이용에 있어서 초기생육 부진이 가장 심각한 문제점으로 대두되고 있다. 따라서 유식물 활력증진을 위한 육종의 기초자료로 이용하기 위하여 종자가 작은 MO-20과 종자가 큰 302921 두 채통을 $15^{\circ}C$와 $25^{\circ}C$의 생육상에서 재배하여 유식물 활력을 비교 검토하였다. 이산화탄소 교환솔(CER)은 적외선 가스분석기를 이용하여 closed system으로 측정하였다. 암호흡솔은 Gilson 호흡계로 측정하였으며 일당 순탄소 축적솔과 유식물 생장분석도 조사하였다. 302921은 MO-20에 비해 종자크기는 약 3.5배 가량이, 최대 신장 자엽 면적은 약 2배 가량이 더 컸다. $25^{\circ}C$에서 출현후 3주까지는 302921의 초기 유식물 생장이 더 양호하였으나 3주 이후부터 시험종료시 까지는 오히려 MO-20이 302921보다 연면적당 CER이 더 높고 건물축적솔도 더 많았다. 반면 $15^{\circ}C$에서는 MO-20이 302921보다 생장이 더 억압 받았다. MO-20의 암호흡솔은 302920보다 약간 높았으나 일당 순이산화탄소 교환솔은 MO-20이 $25^{\circ}C$에서 높았고 $15^{\circ}C$에서는 낮았다. MO-20의 상대생장솔은 $25^{\circ}C$에서는 높은 순동화솔로 인하여 302921보다 높았으나 $15^{\circ}C$에서는 계통간 차이가 별로 없었다.

• 한국재난정보학회 논문집
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• 제19권2호
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• pp.305-312
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• 2023

연구목적: 본 연구에서는 콘크리트 포장의 온도피해를 줄이기 위해 상변화에너지가 큰 PCM을 콘크리트에 혼입하고 이에 따른 성능테스트를 진행하였다. 연구방법:저온 및 고온에 대한 온도피해를 감소시키기 위해 4.5℃와 44℃의 상변화 온도를 가지는 캡슐형 PCM을 10%, 30%, 50% 치환하여 콘크리트에 혼입하였으며 열전대와 변온챔버를 활용하여 열성능 실험과 압축강도 실험을 진행하였다. 연구결과: 열성능 실험 결과 PCM의 혼입은 최대 25%이상의 온도저항성을 향상시키는 것으로 나타났으며 다량 치환시 높은 비열로 모든 온도에서 열저항성을 높이는 것으로 나타났다. 압축강도 실험 결과 30%이상의 치환은 압축강도를 저하시키는 결과를 나타냈으며 PCM의 상변화온도를 기준으로 큰 강도차이를 나타냈다. 결론: PCM의 혼입은 콘크리트의 열성능을 증가시키는 것으로 나타냈으며 PCM의 상변화온도 부근에서 가장 큰 열성능 증가폭을 나타냈다. 또한 가장 높은 치환율인 50% 치환에서 10%~20%의 작은 강도저하가 발생하였으므로 사용성에 큰 문제가 없을 것으로 판단되며 열성능 향상을 위해 추가적인 PCM 투입이 가능할 것으로 판단된다.