• 한국지하수토양환경학회지:지하수토양환경
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• 제16권4호
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• pp.38-52
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• 2011

Sorption and sequential desorption experiments were conducted for Zn using a natural soil (NS) in background status by aging (1, 30 and 100 days). The sorption isotherm showed that Zn had high sorption capacity but low sorption affinity in NS. Sequential desorption was biphasic with appreciable amount of sorbed Zn residing in the desorption-resistant fraction after several desorption steps. The biphasic desorption behavior of Zn was characterized by a biphasic desorption model that includes a linear term to represent labile or easily-desorbing fraction and a Langmuirian-type term to represent desorption-resistant fraction. The biphasic desorption model indicated that the size of the maximum capacity of desorption-resistant fraction ($q^{irr}_{max}$) increased with aging in NS. Desorption kinetics and desorption-resistance of Zn in the soils collected from mine tailings (MA, MB and MC collected from surface, subsurface soils and mine waste, respectively) were investigated and compared to the bioavailability to earthworm (Eisenia fetida). Desorption kinetic data of Zn were fitted to several desorption kinetic models. The ratio ($q_{e,d}/q_0$) of remaining Zn at desorption equilibrium ($q_{e,d}$) to initial sorbed concentration ($q_0$) was in the range of 0.53~0.90 in the mine tailings which was higher than that in NS, except MA. The sequential desorption from the mine tailings with 0.01M Na$NO_3$ and 0.01M $CaCl_2$ showed that appreciable amounts of Zn are resistant to desorption due to aging or sequestration. The SM&T (Standard Measurements and Testing Programme of European Union) analysis showed that the sum of oxidizable (Step III) and residual (Step IV) fractions of Zn was linearly related with its desorption-resistance ($q^{irr}_{max}$) determined by the sequential desorption with 0.01M Na$NO_3$ ($R^2$= 0.9998) and 0.01M $CaCl_2$ ($R^2$= 0.8580). The earthworm uptake of Zn and the desorbed amount of Zn ($q_{desorbed}$ = $q_0-q_{e,d}$) in MB soil were also linearly related ($R^2$ = 0.899). Our results implicate that the ecological risk assessment of heavy metals would be possible considering the relation between desorption behaviors and bioavailability to earthworm.

• 상하수도학회지
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• 제22권4호
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• pp.421-427
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• 2008

UV disinfection is widely used in water treatment facilities and wastewater treatment plant because of its effectiveness to removal of pathogen and Giardia which is resistant to traditional chemical disinfection. As a design and performance tool of UV disinfection system, 3 dimensional UV intensity models were composed and simulated to compare each other and to find affecting factors in this study. Reflection, refraction and absorption are important parameters in UV intensity model and MPSS and MSSS model can reflect these parameters while LSI model can not. Absorption is the most important parameters among the reflection, refraction, absorption and shadowing so, this should not be neglect. Based on this simulation, shadowing effect is negligible when the number of installed lamp is a few but, this effect can not be neglectable when the number of installed lamp is quite a few. The errors according to shadowing effect is increased as the number of lamp installed increased.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.220-222
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• 2005

The Cold cathode fluorescent lamp(CCFL) are used to illuminate the liquid crystal display(LCD). Ballasts are required for CCFL because the lamp need high starting voltage and behave negative dynamic resistant characteristics in the desired region of operation. In this paper, the lamp impedance model is proposed, and this model is established from some equations and measured electrical characteristics of CCFL. The validity of porposed lamp model is verified from the simulation and experimental results.

• 한국농림기상학회지
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• 제16권4호
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• pp.259-266
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• 2014

산불 확산 패턴 분석은 산림 생태계 안정화를 이해하는데 중요한 요소이다. 하지만 규모의 문제로 인해 실제적인 실험이 불가능하여 많은 학자들이 시뮬레이션 모델을 이용하여 산불 확산의 행동기작을 이해하고 산림 피해를 예측하였다. 그러나 많은 모델들이 연료의 종류, 바람, 습도 같은 여러 환경 요소들의 복잡한 관계를 표현하는데 한계를 가지고 있다. 본 논문에서는 지형의 구조와 두 종의 나무들로 구성된 산림에서 미치는 영향을 분석하는 간단한 모델을 제안하였다. 두 종의 나무는 가연성이 높은 나무와 가연성이 낮은 나무가 있으며, 서로 다른 산불 전이 확률을 가지고 있다. 전체 나무는 시뮬레이션 공간에 0.5에서 1.0까지의 비율로 무작위로 배치된다. 가연성이 높은 나무는 가연성이 낮은 나무 보다 높은 산불 전이 확률을 가진다. 전소한 나무의 수를 기준으로 지형의 구조와 전체 나무의 밀도가 산불 확산에 얼마나 영향을 미치는지 민감도를 분석하였다. 우리는, 본 논문에서 제시한 모델이 앞으로 산불 확산 패턴을 연구하는데 유용할 것으로 기대한다.

• International Journal of Oral Biology
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• 제31권2호
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• pp.33-43
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• 2006

Dysplasia-associated seizure disorders are markedly resistant to pharmacological intervention. Relatively little research has been conducted studying the effects of antiepileptic drugs(AEDs)on seizure activity in a rat model of dysplasia. We have used rats exposed to methylazoxymethanol acetate(MAM) in utero, an animal model featuring nodular heterotopia, to investigate the effects of AEDs in the dysplastic brain. Pilocarpine was used to induce acute seizure in MAM-exposed and age-matched vehicle-injected control animals. Field potential recordings were used to monitor amplitude and numbers of population spikes, and paired pulse inhibition in response to stimulation of commissural pathway. Two commonly used AEDs were tested: diazepam 5, 2.5 mg/kg; phenytoin 40, 60 mg/kg. Diazepam(DZP) and phenytoin(PHT) reduced the amplitude of population spike in control and MAM-exposed rats. However, the amplitude of population spike was nearly eliminated in control rats as compared to the MAM-exposed rats. Pharmaco-resistance was tested by measuring seizure latencies in awake rats after pilocarpine administration(320 mg/kg, i.p.) with and without pretreatment with AEDs. Pre-treatment with PHT 60 mg prolonged seizure latency in control rats, but not in MAM-exposed animals. The main findings of this study are that acute seizures initiated in MAM-exposed rats are relatively resistant to standard AEDs assessed in vivo. These data suggest that animal model with cortical dysplasia can be used to screen the effects of potential AEDs.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.947-952
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• 2007

Mycobacterium tuberculosis is a pathogen responsible for 2-3 million deaths every year worldwide. The emergence of drug-resistant and multidrug-resistant tuberculosis has increased the need to identify new antituberculosis targets. Acetohydroxy acid synthase, (AHAS, EC 2.2.1.6), an enzyme involved in branched-chain amino acid synthesis, has recently been identified as a potential anti-tuberculosis target. To assist in the search for new inhibitors and “receptor-based” design of effective inhibitors of tubercular AHAS (TbAHAS), we constructed four different structural models of TbAHAS and used one of the models as a target for virtual screening of potential inhibitors. The quality of each model was assessed stereochemically by PROCHECK and found to be reliable. Up to 89% of the amino acid residues in the structural models were located in the most favored regions of the Ramachandran plot, which indicates that the conformation of each residue in the models is good. In the models, residues at the herbicide-binding site were highly conserved across 39 AHAS sequences. The binding mode of TbAHAS with a sulfonylurea herbicide was characterized by 32 hydrophobic interactions, the majority of which were contributed by residue Trp516. The model based on the highest resolution X-ray structure of yeast AHAS was used as the target for virtual screening of a chemical database containing 8300 molecules with a heterocyclic ring. We developed a short list of molecules that were predicted to bind with high scores to TbAHAS in a conformation similar to that of sulfonylurea derivatives. Five sulfonylurea herbicides that were calculated to efficiently bind TbAHAS were experimentally verified and found to inhibit enzyme activity at micromolar concentrations. The data suggest that this time-saving and costeffective computational approach can be used to discover new TbAHAS inhibitors. The list of chemicals studied in this work is supplied to facilitate independent experimental verification of the computational approach.

• The Korean Journal of Physiology and Pharmacology
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• 제10권5호
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• pp.235-242
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• 2006

Cortical malformation-associated epileptic seizures are resistant to conventional anticonvulsant drugs. Relatively little research has been conducted on the effects of antiepileptic drugs (AEDs) on seizure activity in a rat model of dysplasia. We have used rats exposed to methylazoxymethanol acetate (MAM) in utero, an animal model featuring nodular heterotopia, to investigate the effects of ethosuximide (ETX) in the dysplastic brain. Pilocarpine was used to induce acute seizure in MAM-exposed and age-matched vehicle-injected control animals. Field potential recordings were used to monitor the amplitude and number of population spikes, and paired pulse inhibition in response to stimulation of the commissural pathway. Pharmaco-resistance was tested by measuring seizure latencies after pilocarpine administration (320 mg/kg, Lp.) with and without pre-treatment with ETX. Pre-treatment with 300 mg of ETX significantly prolonged the latency to the status epilepticus (SE) in both control and MAM-treated groups. Pre-treatment with ETX 100mg and ETX 200 mg had little effect in MAMexposed rats. However, ETX 200 mg prolonged the latency to the SE in control groups. Spontaneous field potential and secondary after-discharges were higher for MAM-treated rat in comparison with control rats injects with ETX. The main findings of this study are that acute seizures initiated in MAM-exposed rats are relatively resistant to standard ETX assessed in vivo. These data suggest that ETX do not prolong seizure latencies in MAM-rats exposed to pilocarpine.

• Parasites, Hosts and Diseases
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• 제62권1호
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• pp.42-52
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• 2024

Antimalarial drugs are an urgently need and crucial tool in the campaign against malaria, which can threaten public health. In this study, we examined the cytotoxicity of the 9 antimalarial compounds chemically synthesized using SKM13-2HCl. Except for SKM13-2HCl, the 5 newly synthesized compounds had a 50% cytotoxic concentration (CC₅₀) >100 μM, indicating that they would be less cytotoxic than SKM13-2HCl. Among the 5 compounds, only SAM13-2HCl outperformed SKM13-2HCl for antimalarial activity, showing a 3- and 1.3-fold greater selective index (SI) (CC₅₀/IC₅₀) than SKM13-2HCl in vitro against both chloroquine-sensitive (3D7) and chloroquine -resistant (K1) Plasmodium falciparum strains, respectively. Thus, the presence of morpholine amide may help to effectively suppress human-infectious P. falciparum parasites. However, the antimalarial activity of SAM13-2HCl was inferior to that of the SKM13-2HCl template compound in the P. berghei NK65-infected mouse model, possibly because SAM13-2HCl had a lower polarity and less efficient pharmacokinetics than SKM13-2HCl. SAM13-2HCl was more toxic in the rodent model. Consequently, SAM13-2HCl containing morpholine was selected from screening a combination of pharmacologically significant structures as being the most effective in vitro against human-infectious P. falciparum but was less efficient in vivo in a P. berghei-infected animal model when compared with SKM13-2HCl. Therefore, SAM13-2HCl containing morpholine could be considered a promising compound to treat chloroquine-resistant P. falciparum infections, although further optimization is crucial to maintain antimalarial activity while reducing toxicity in animals.

• 전기학회논문지
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• 제60권12호
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• pp.2326-2332
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• 2011

eLoran is enhanced Loran-C and eLoran is researched for as GPS backup system because this system is resistant to signal interference and has high accuracy. TOA measurements of eLoran include errors proportional to the range such as PF, SF, ASF and EF. Therefore these error factors must be compensated for improved accuracy of position. Generally, error models or GPS aided compensation methods are used, but these methods are limited by lack of infrastructure or system performance. Therefore, this paper proposes new model of error factors included in eLoran TOA measurements and navigation algorithm using this model. Error factors in this model are sum of a certain size of error and error proportional to the range. And feasibility and performance of proposed navigation algorithm are verified by using raw measurements.

• 아동학회지
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• 제20권1호
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• pp.147-164
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• 1999

The purpose of this study was to investigate (1) intergenerational transmission from mother's internal working model of relationships formed in her childhood and infant's attachment patterns and (2) the associations among maternal working models, maternal sensitivity, and infant attachment patterns. The subjects were twenty 12- to 20-month-old infants and their mothers. The Adult Attachment Interview (1996) was used to assess mother's internal work model of relationships. Interviews were audio-recorded and transcribed verbatim. Each dyad was videotaped in the modified Ainsworth Strange Situation(1978) and filmed for 3 minutes in the Questionaire Situation of Smith and Pederson (1988). Mothers were classified as autonomous(F), dismissing(Ds), preoccupied(E), or unresolved/disorganized(Ud). Infants were classified as secure(B), insecure-avoidant(A), or insecure-resistant(C). Exact A/B/C/D and Ds/F/E/Ud agreement was observed in 55% of the dyads. Maternal sensitivity was related to infant attachment patterns but not to maternal working models.