• 생명과학회지
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• 제18권2호
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• pp.148-153
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• 2008

Arabidopsis의 피토크롬 2중 돌연변이형 (phrAB)은 야생형 (WT)과 비교하여 뿌리의 굴중성 반응이 지연되었다. 중력 자극을 받은 지 8시간 후에 돌연변이체의 굴중성 반응은 야생형의 48%를 나타내었다 지연된 반응은 중력 자극을 준 후 1.5 시간 뒤에 나타났다. 12시간 동안 야생형과 돌연변이형의 뿌리 절편에서 에틸렌 생성을 측정하였다. 돌연변이형의 에틸렌 생성은 12시간이 경과한 후에 야생형의 40% 정도로 감소되었다. 이러한 결과는 피토크롬이 에틸렌 생성과 연관되어 있음을 제시하고 있다. 일반적으로 에틸렌은 식물의 뿌리나 줄기를 억제한다. 본 연구에서는 에틸렌 전구체인 1-aminocycloprpane-1-carboxylic acid (ACC)를 처리하여 뿌리의 생장을 측정하였다. 야생형은 ACC 존재하에 뿌리 생장이 억제되었으나, 돌연변이형은 야생형만큼 억제를 나타내지 않았다. 이 결과를 확인하기 위하여 ACC 존재하에 굴중성 반응을 측정한 결과, 야생형은 ACC가 없는 경우와 비교하여 37.4%의 억제를 나타냈으나, 돌연변이형은 ACC가 없는 경우와 비교하여 6.6%만을 억제하였다. 이 결과는 피토크롬이 에틸렌 생성을 통하여 뿌리 굴중성 반응을 조절한다는 것을 제시한다.

• 대한음성학회지:말소리
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• 제33_34호
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• pp.71-89
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• 1997

In the framework of linear representation which allows for no internal structure within features, there is no way to represent nonlinear phonological phenomena such as complex segments. This paper shows how we carl solve some problems of the linear feature theory in relation to the hierarchical feature theory. The purpose of this paper is to explain lateral assimilation under hierarchical feature representation. Although arguments for the position of classes of distinctive features have been made the position of (lateral) remains the issue of debate. Sagey(1988) argues that the feature [lateral] is structurally dependent on the root node. In contrast Rice & Avery (1991) put the feature (lated) under the spontaneous voicing. I have discussed previous studies of feature hierarchy and I propose a revised model of feature representation. Within this model I have shown how well feature geometry describes lateralization as feature spreading.

• Nuclear Engineering and Technology
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• 제29권5호
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• pp.375-384
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• 1997

Relative power density distributions of the Kori Unit 1 pressurized water reactor are calculated by Monte Carlo modeling with the MCNP code. The Kori Unit 1 core is modeled on a three-dimensional representation of the one-eighth of the reactor in-vessel component with reflective boundaries at 0 and 45 degrees. The axial core model is based on half core symmetry and is divided into four axial segments. Fission reaction density in each rod is calculated by following 100 cycles with 5,000 test neutrons in each cycle after starling with a localized neutron source and ten noncontributing settle cycles. Relative assembly power distributions are calculated from fission reaction densities of rods in assembly. After 100 cycle calculations, the system converges to a k value of 1.00039 $\geq$ 0.00084. Relative assembly power distribution is nearly the same with that of the Kori Unit 1 FSAR. Applicability of the full-scope Monte Carlo simulation in the power distribution calculation is examined by the relative root moan square error of 2.159%.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.1093-1096
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• 1999

In this paper, video image segmentation algorithm based on color histogram and change detector is proposed. Color histograms are calculated from both changed region which is detected in the previous and current frame and unchanged region. With each histogram, modes and valleys are detected. Then, color vectors are calculated by averaging pixels in modes. Markers are extracted by labeling color vectors that represent modes, the watershed algorithm is applied to determine uncertain region. In growing region, the root mean square(RMS) of the distance between average pixel in marker region and adjacent pixel is used as a measure. The proposed algorithm based on color histogram and change detector segments video image fastly and effectively. And simulation results show that the proposed method determines the exact boundary between background and foreground.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2005년도 춘계학술발표논문집
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• pp.269-271
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• 2005

본 연구는 수선화 구근의 각 조직으로부터 기내배양시 캘러스형성과 신초재분화를 위한 성장조절제의 효과를 측정하기 써하여 시행되었다. 신초형성과 callus의 형성은 기저부를 포함하는 floral axis에서 $50\%$의 신초발아율을 관찰하였고 scale 에서는 신초형성이 거의 관찰되지 않았다. 그리고 floral axis만을 치상한 경우는 아주 저조한 신초형성율이 관찰되었다. 지저부를 포함한 floral axis의 신초형성은 callus의 형성과 같은 NAA 0.5 mg/L과 BA 1.0 mg/L을 포함하는 MS 배지에서 만족할만한 결과를 얻었다. 신초형성으로부터 모든 신초가 형성되기까지는 약 140일이 소요되었다. 신초가 형성된 구근조직을 NAA 5.0 mg/L과 TDZ 0.02 mg/L을 포함하는 뿌리유도 MS배지에서 뿌리가 유도되는 결과를 얻었다. 본 실험에서는 수선화의 재 분화에 있어서 구근의 조직에 따라 신초형성이 다르게 나타남을 발견 할 수 있었다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.550-556
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• 2000

Three floating islands were constructed on the surface of the reservoir, each consisting of 10 16-㎡ (4${\times}$4 m) segments, made of wood frames and floats. Three species of aquatic macrophytes were planted in each island on June, 1998. Phragmites australis was considered as the suitable aquatic macrophyte for the floating islands since it maintained the most efficient root and shoot balance among the macrophytes. The net primary productivity of P. Australis was 3,604 g/㎡ based on dry weight in 1999, with uptake rates of nitrogen and phosphorus estimated at 77.4 g/㎡/yr and 5.7 g/㎡/yr, respectively. The result of water quality simulation for the floating islands showed that, through adsorption of nutrients and light screening, they could reduce the amount of phytoplankton, thereby decreasing COD concentration.

• Journal of Plant Biotechnology
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• 제1권2호
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• pp.101-107
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• 1999

The leaf blade-segments of albino tobacco (Nicotiana tabacum L.) were cultured on MS media containing different concentrations of BAP (0, 0.4, 2.2, 4.4, 22.2 ${\mu}{\textrm}{m}$) with or without NAA (0, 0.5, 2.7 ${\mu}{\textrm}{m}$). Multiple shoots were induced on the media containing 0.4 to 2.2 ${\mu}{\textrm}{m}$ BAP. The best condition for multiple shoot induction with root formation was MS media containing 4.4 ${\mu}{\textrm}{m}$ BAP and 0.5 ${\mu}{\textrm}{m}$ NAA. The regenerated albino plants showed a significant reduction in accumulation of chlorophylls and carotenoids. The drastic reduction of the pigments content was associated with the distinct alterations in gene expression in the albino plants. firstly, the expression of plastid genes, such as rbcL, psbA, 165 rDNA and 235 rDNA, was reduced at the level of transcripts in the regenerated albino plants. Secondly, the alteration of structure of the plastid genes was not detected in the albino plants. However, the copy number of the plastid genes whose transcription level was reduced greatly was increased approximately two-fold, although the transcriptions of nuclear gene (255 rDNA) showed the wild-type level.

• 대한의용생체공학회:의공학회지
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• 제37권1호
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• pp.15-20
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• 2016

Essential tremor is a neurological disorder with a tremor of the arms and hands. It is well known that essential tremor is characterized by the postural tremor and the action tremor. There has been no report on the quantitative difference in the characteristics of two tremor types. The purpose of this study was to investigate the possible difference in tremor characteristics of postural and action tremors. Seventeen patients with essential tremor ($68.9{\pm}7.9years$, 7 men, 10 women) participated in this study. Patients performed the tasks of postural maintenance (arms outstretched) and daily actions (spiral drawing). Three-axes (pitch, roll and yaw) gyro sensors were attached on index finger, back of hand and forearm, from which the segment and the joint angular velocities were calculated. Outcome measure was the tremor amplitude defined as the root-mean-square mean of the vector-sum angular velocity at segments and joints. Two-way ANOVA showed that task and joint had main factor on the tremor amplitude (p < 0.05). Post-hoc analysis revealed that tremor amplitude at the metacarpo-phalangeal joint was not affected by task (p > 0.05). However, tremor amplitude at the wrist joint differed among the tasks (p < 0.05), and it was greater in the action tasks than in postural task. Tremor was greater at finger segments than at hand and forearm and it increased in action tasks. The results of this study would be helpful for the understanding and task-specific treatments of the essential tremor.

• The Korean Journal of Pain
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• 제21권3호
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• pp.187-196
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• 2008

Background: Upregulation of one type of the pro-inflammatory chemokine (CCL2) and its receptor (CCR2) following peripheral nerve injury contributes to the induction of neuropathic pain. Here, we examined whether another type of chemokine (CCL3) is involved in neuropathic pain. Methods: We measured changes in mechanical and thermal sensitivity in the hind paws of naïve rats or rats with an L5 spinal nerve ligation (SNL) after intra-plantar injection of CCL3 or met-RANTES, an antagonist of the CCL3 receptor, CCR1. We also measured CCL3 levels in the sciatic nerve and the hind paw skin as well as CCR1 expression in dorsal root ganglion (DRG) cells from the lumbar spinal segments. Results: Intra-plantar injection of CCL3 into the hind paw of naive rats mimicked L5 SNL-produced hyperalgesia. Intra-plantar injection of met-RANTES into the hind paw of rats with L5 SNL attenuated hyperalgesia. L5 SNL increased CCL3 levels in the sciatic nerve and the hind paw skin on the affected side. The number of CCR1-positive DRG cells in the lumbar segments was not changed following L5 SNL. Conclusions: Partial peripheral nerve injury increases local CCL3 levels along the degenerating axons during Wallerian degeneration. This CCL3 binds to its receptor, CCR1, located on adjacent uninjured afferents, presumably nociceptors, to induce hyperalgesia in the neuropathic pain state.

• Journal of Plant Biotechnology
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• 제41권4호
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• pp.236-241
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• 2014

An efficient regeneration protocol for stem disc culture of Populus euramericana, which is important species for bioenergy resource in agroforestry, was established. The number of explants that were obtained and the number of explants that regenerated varied with the genotypes. However, in all the genotypes, stem disc culture produced more regenerated shoots than did in axillary bud culture. A comparison of the effects of cytokinin type and concentration on shoot regeneration in different explants (i.e., petiole, leaf, and root segments of P. euramericana) revealed that a concentration of $0.002mg\;l^{-1}$ thidiazuron (TDZ) used on petiole segments resulted in the greatest shoot regeneration (95.83%). The hormonal requirements for the greatest shoot regeneration in the three explant types varied. Different concentrations of $AgNO_3$ and $CoCl_2$ were added separately to the medium to stop the yellowing and subsequent necrosis of the regenerated shoots. Lower concentrations (3 and $5mg\;l^{-1}$) of these compounds improved shoot regeneration and elongation, compared with the control. The in vitro-regenerated shoots were transferred to rooting medium and subsequently acclimatized. The highly efficient regeneration system of P. euramericana reported here can be used for mass propagation of this recalcitrant for regeneration, economically important tree species.