• 원예과학기술지
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• 제33권6호
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• pp.854-859
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• 2015

본 시험은 배양액 내 pH 변화에 따른 이온과 EC의 모형을 구명하고자 수행하였다. 배양액 내 $HPO_4{^{-2}}$와 $H_2PO_4{^-}$의 변량에 따른 pH가 변하는데, pH 4.0-5.0은 EC의 변량이 상승하고, pH 5.0-7.0은 EC의 변량이 완만하고, pH 7.0-8.0은 다시 상승하였다. 배양액 내 다량원소의 변량을 보면, pH가 상승할수록 K, Ca, N, P의 이온 농도도 증가하는데, 특히 K과 P의 변량이 크게 나타났다. 반면 Mg와 S의 변량은 일정하게 유지되었다. 배양액의 IBM(ion balance model)에 따른 분석에서, EC의 변량은 크게 변하지 않고, 이온의 균형점이 a분면에서 d분면으로 이동하면 pH가 상승하면서 음이온 보다 양이온이 증가하는 것으로 나타났다. 또한 pH 변량이 높을수록 EC 중앙선으로부터 멀어져 배양액의 이온 불균형이 증가되었다. $HPO_4{^{-2}}$와 $H_2PO_4{^-}$의 변량에 대한 K와 Ca의 당량비 보정은 pH가 증가할수록 K는 감소하지만 Ca는 증가하였고, EC 변량의 영향보다 큰 것으로 나타났다. K와 Ca의 당량비 보정에 따른 pH 변량은 0.97의 이차 다항식 상관모형을 나타냈다. 본 연구를 통해 인산염의 구배에 따른 pH, 이온, EC의 변량에 대하여 pH 변량 모형이 구명되었다.

• Nutrition Research and Practice
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• 제9권5호
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• pp.480-488
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• 2015

BACKGROUND/OBJECTIVES: Alzheimer's disease (AD) is characterized by deficits in memory and cognitive functions. The accumulation of amyloid beta peptide ($A{\beta}$) and oxidative stress in the brain are the most common causes of AD. MATERIALS/METHODS: Caffeic acid (CA) is an active phenolic compound that has a variety of pharmacological actions. We studied the protective abilities of CA in an $A{\beta}_{25-35}$-injected AD mouse model. CA was administered at an oral dose of 10 or 50 mg/kg/day for 2 weeks. Behavioral tests including T-maze, object recognition, and Morris water maze were carried out to assess cognitive abilities. In addition, lipid peroxidation and nitric oxide (NO) production in the brain were measured to investigate the protective effect of CA in oxidative stress. RESULTS: In the T-maze and object recognition tests, novel route awareness and novel object recognition were improved by oral administration of CA compared with the $A{\beta}_{25-35}$-injected control group. These results indicate that administration of CA improved spatial cognitive and memory functions. The Morris water maze test showed that memory function was enhanced by administration of CA. In addition, CA inhibited lipid peroxidation and NO formation in the liver, kidney, and brain compared with the $A{\beta}_{25-35}$-injected control group. In particular, CA 50 mg/kg/day showed the stronger protective effect from cognitive impairment than CA 10 mg/kg/day. CONCLUSIONS: The present results suggest that CA improves $A{\beta}_{25-35}$-induced memory deficits and cognitive impairment through inhibition of lipid peroxidation and NO production.

• Journal of Computing Science and Engineering
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• 제3권4호
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• pp.238-259
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• 2009

In this paper we discuss personal data management with mobile devices, an activity requiring the composition of services offered by standard suites of applications. We propose a data model and an interface model that allows users to define activities, tasks and services, to navigate among them according to the evolution of the personal situation as perceived and interpreted by the users themselves. The interface model acts as a lens exploring the situation, zooming into the details, covering different areas of the personal data, supporting the user in the role of a composer of personal services.

• Journal of Biosystems Engineering
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• 제38권2호
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• pp.129-137
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• 2013

Purpose: Modeling has been used for elucidating the mechanism of complex biosystems. In spite of importance and uniqueness of adolescent calcium (Ca) metabolism characterized by a threshold Ca intake, its regulatory mechanism has not been covered and even not proposed. Hence, this study aims at model-based proposing potential mechanisms regulating adolescent Ca metabolism. Methods: Two different hypothetic mechanisms were proposed. The main mechanism is conceived based on Ca-protein binding which induces renal Ca filtration, while additional mechanism assumed that active renal Ca re-absorption regulated Ca metabolism in adolescents. Mathematical models were developed to represent the proposed mechanism and simulated them whether they could produce adolescent Ca profiles in serum and urine. Results: Simulation showed that both mechanisms resulted in the unique behavior of Ca metabolism in adolescents. Based on the simulation insulin-like growth factor-1 (IGF-1) is suggested as a potential regulator because it is related to both growth, a remarkable characteristic of adolescence, and Ca metabolism including absorption and bone accretion. Then, descriptive modeling is employed to conceptualize the hypothesized mechanisms governing adolescent Ca metabolism. Conclusions: This study demonstrated that modeling is a powerful tool for elucidating an unknown mechanism by simulating potential regulatory mechanisms in adolescent Ca metabolism. It is expected that various analytic applications would be plausible in the study of biosystems, particularly with combination of experimental and modeling approaches.

• 대한교통학회지
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• 제19권3호
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• pp.133-144
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• 2001

본 연구에서는 대규모 네트워크에 적용 가능한 미시적 교통류 시뮬레이션 모형을 개발하였다. 본 연구는 대규모 가로망에 대한 미시적 교통류 시뮬레이션 시스템개발의 첫 번째 단계로, 연속류 구간을 중심으로 우리나라의 가로망 구조, 차량 주행행태에 적합한 미시적 교통류 시뮬레이션 모형개발에 초점을 두었다. 차량 전이 모형으로는 Cellular Automata 모형(CA모형)을 기반으로 하였으며, 기존의 CA모형 중 교통공학적 측면에서 문제가 있다고 판단되는 부분에 대해서는 새로운 모형을 개발하거나 수정하여 적용하였다. 개발된 모형의 모의실험을 통해 기존의 거시적 교통류 시뮬레이션 모형에서 설명할 수 없었던 여러 교통현상(합류, 차로축소, 분류등으로 유발되는 교통현상)을 설명할 수 있는 것으로 확인되었고, 또한 본 모형은 우리나라의 가로망구조에 기반을 두고 개발되었기 때문에 기존에 외국에서 개발된 미시적 시뮬레이션 모형이 표현하지 못했던 가로망에 대한 교통류 시뮬레이션이 가능한 것으로 나타났다.

• 대기
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• 제30권2호
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• pp.155-167
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• 2020

In order to produce more detailed and accurate information of river discharge and freshwater discharge, global high-resolution hydrodynamic model (CaMa-Flood) is applied to an operational land surface model of global seasonal forecast system. In addition, bias correction to grid runoff for the hydrodynamic model is attempted. CaMa-Flood is a river routing model that distributes runoff forcing from a land surface model to oceans or inland seas along continentalscale rivers, which can represent flood stage and river discharge explicitly. The runoff data generated by the land surface model are bias-corrected by using composite runoff data from UNH-GRDC. The impact of bias-correction on the runoff, which is spatially resolved on 0.5° grid, has been evaluated for 1991~2010. It is shown that bias-correction increases runoff by 30% on average over all continents, which is closer to UNH-GRDC. Two experiments with coupled CaMa-Flood are carried out to produce river discharge: one using this bias correction and the other not using. It is found that the experiment adapting bias correction exhibits significant increase of both river discharge over major rivers around the world and continental freshwater discharge into oceans (40% globally), which is closer to GRDC. These preliminary results indicate that the application of CaMa-Flood as well as bias-corrected runoff to the operational global seasonal forecast system is feasible to attain information of surface water cycle from a coupled suite of atmospheric, land surface, and hydrodynamic model.

• The Korean Journal of Pain
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• 제33권2호
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• pp.131-137
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• 2020

Background: Among various diseases that accompany pain, complex regional pain syndrome (CRPS) is one of the most frustrating for patients and physicians. Recently, many studies have shown functional and anatomical abnormalities in the brains of patients with CRPS. The calcium-related signaling pathway is important in various physiologic processes via calmodulin (CaM) and calcium-calmodulin kinase 2 (CaMK2). To investigate the cerebral mechanism of CRPS, we measured changes in CaM and CaMK2 expression in the cerebrum in CRPS animal models. Methods: The chronic post-ischemia pain model was employed for CRPS model generation. After generation of the animal models, the animals were categorized into three groups based on changes in the withdrawal threshold for the affected limb: CRPS-positive (P), CRPS-negative (N), and control (C) groups. Western blot analysis was performed to measure CaM and CaMK2 expression in the rat cerebrum. Results: Animals with a decreased withdrawal threshold (group P) showed a significant increment in cerebral CaM and CaMK2 expression (P = 0.013 and P = 0.021, respectively). However, groups N and C showed no difference in CaM and CaMK2 expression. Conclusions: The calcium-mediated cerebral process occurs after peripheral injury in CRPS, and there can be a relationship between the cerebrum and the pathogenesis of CRPS.

• 한국식품저장유통학회지
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• 제9권3호
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• pp.261-266
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• 2002

CA저장 중 저장기체 조성에 따른 사과 Fuji의 증산속도를 측정하고, 같은 조건에서 증산속도를 예측하기 위한 수학적 모델을 설정하여 증산속도를 예측하였다. 온도 $0^{\circ}C$, 상대습도 98%, 공기 유속 0.25m/s의 저장조건에서 6주 동안 CA저장하였을 때 사과 Fuji의 호흡속도는 일반저온저장에 비하여 50%이하로 낮출 수 있었다. 같은 저장조건에서 일반저온저장에서의 사과의 증산속도가 CA저장에 비하여 50~70 % 높았으며, 일정한 산소농도의 CA저장에서는 저장기체 중 이산화탄소농도가 높을수록 증산속도는 감소하는 것으로 나타났다. 본 연구에서 채택한 모델로 예측한 증산속도는 실측치와 유사한 값을 나타내어 본 연구에서 채택한 모델로 CA 저장 중 저장기체 조성에 따른 사과 Fuji의 증산속도를 잘 예측할 수 있었다. 사과의 증산속도는 호흡열량에 비례하여 증가하는 경향을 나타내었으나 증산속도의 증가폭은 호흡열량의 증가폭에 미치지 못하였다. 이는 호흡열량이 증가하면 사과의 증발표면의 온도가 높아져서 증산속도가 커질 수 있게 되지만, 증산속도의 증가에 따른 증발잠열의 증가가 증발표면의 온도를 미세하게 낮추어 주므로 일어나는 현상으로 볼 수 있다.

• Biomolecules & Therapeutics
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• 제20권2호
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• pp.171-176
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• 2012

HaCaT cells are the immortalized human keratinocytes and have been extensively used to study the epidermal homeostasis and its pathophysiology. T helper cells play a role in various chronic dermatological conditions and they can affect skin barrier homeostasis. To evaluate whether HaCaT cells can be used as a model cell system to study abnormal skin barrier development in various dermatologic diseases, we analyzed the gene expression profile of epidermal differentiation markers of HaCaT cells in response to major T helper (Th) cell cytokines, such as $IFN{\gamma}$, IL-4, IL-17A and IL-22. The gene transcriptional profile of cornified envelope-associated proteins, such as filaggrin, loricrin, involucrin and keratin 10 (KRT10), in HaCaT cells was generally different from that in normal human keratinocytes (NHKs). This suggests that HaCaT cells have a limitation as a model system to study the pathophysiological mechanism associated with the Th cell cytokine-dependent changes in cornified envelope-associated proteins which are essential for normal skin barrier development. In contrast, the gene transcription profile change of human ${\beta}2$-defensin (HBD2) in response to $IFN{\gamma}$, IL-4 or IL-17A in HaCaT cells was consistent with the expression pattern of NHKs. $IFN{\gamma}$ also up-regulated transglutaminase 2 (TGM2) gene transcription in both HaCaT cells and NHKs. As an alternative cell culture system for NHKs, HaCaT cells can be used to study molecular mechanisms associated with abnormal HBD2 and TGM2 expression in response to $IFN{\gamma}$, IL-4 or IL-17A.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권5호
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• pp.2499-2522
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• 2017

Multi-hop networks are a low-setup-cost solution for enlarging an area of network coverage through multi-hop routing. Carrier sense multiple access with collision avoidance (CSMA/CA) is frequently used in multi-hop networks. Multi-hop networks face multiple problems, such as a rise in contention for the medium, and packet loss under heavy-load, saturated conditions, which consumes more bandwidth due to re-transmissions. The number of re-transmissions carried out in a multi-hop network plays a major role in the achievable quality of service (QoS). This paper presents a statistical, analytical model for the end-to-end delay of contention-based medium access control (MAC) strategies. These strategies schedule a packet before performing the back-off contention for both differentiated heterogeneous data and homogeneous data under saturation conditions. The analytical model is an application of Markov chain theory and queuing theory. The M/M/1 model is used to derive access queue waiting times, and an absorbing Markov chain is used to determine the expected number of re-transmissions in a multi-hop scenario. This is then used to calculate the expected end-to-end delay. The prediction by the proposed model is compared to the simulation results, and shows close correlation for the different test cases with different arrival rates.