• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.2
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• pp.16-27
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• 2011

Embryo is a very early stage of the development of multicellular organism such as animals and plants. It is an important research target for studying ontogeny because the fundamental body system of multicellular organism is determined during an embryo state. Researchers in the developmental biology have a large volume of embryo image databases for studying embryos and they frequently search for an embryo image efficiently from those databases. Thus, it is crucial to organize databases for their efficient search. Hierarchical clustering methods have been widely used for database organization. However, most of previous algorithms tend to produce a highly skewed tree as a result of clustering because they do not simultaneously consider both the size of a cluster and the number of objects within the cluster. The skewed tree requires much time to be traversed in users' search process. In this paper, we propose a method that effectively organizes a large volume of embryo image data in a balanced tree structure. We first represent embryo image data as a similarity-based graph. Next, we identify clusters by performing a graph partitioning algorithm repeatedly. We check constantly the size of a cluster and the number of objects, and partition clusters whose size is too large or whose number of objects is too high, which prevents clusters from growing too large or having too many objects. We show the superiority of the proposed method by extensive experiments. Moreover, we implement the visualization tool to help users quickly and easily navigate the embryo image database.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.1257-1259
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• 2011

본 논문에서는 배아 데이터의 효율적인 검색을 지원하는 시각화 도구인 Em-Viz의 설계 및 구현에 관하여 논의한다. Em-Viz는 계층적으로 구조화된 대용량 배아 데이터베이스를 기반으로 구현된 시각화 도구로 사용자가 원하는 배아 데이터를 빠르고 정확하게 검색 할 수 있도록 지원한다.

• Journal of Industrial Convergence
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• v.17 no.4
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• pp.39-43
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• 2019

Mouse embryonic stem cell could show an substitutional materials of cells of neuron differentiation, positively increasing their effectiveness in the treatment of nervous symptom. We examined that mouse embryonic stem cells (mESCs) can be induced to undergo neuronal differentiation. After neuronal induction, the phenotype of mESCs changed towards neuronal morphology and mESCs were injected into the lateral ventricle of the experimental animal brain. Transplanted cells migrated to various parts of the brain and ischemic brain injury by middle cerebral artery occlusion (MCAO) increased their migration to the injured cortex. Intracerebral grafting of mESCs mostly improve sensory and motor nervous system of neurological injury in focal cerebral rats.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.280-282
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• 2005

초파리 초기 발생과정은 gap 유전자, pair-rule 유전자, polarity 유전자의 세 가지 유전자 그룹에 의해서 조직화 된다. Gap 유전자들에 의해 pair-rules 유전자들의 발현이 조절되며, 이들에 의해 결국 polarity 유전자들의 발현을 조절함으로써, 정확한 위치에서 각 기관의 형성을 유도한다. 특히 분열 14단계에서는 pair-rule 유전자 중의 하나인 eve 유전자의 발현이 조절되는데, eve 유전자는 배아의 분할의 줄무늬를 형성시키는 유전자에 해당된다. 본 논문에서는 eve 유전자의 발현조절자인 hunchback, giant, kruppel, bicoid의 gap 유전자들로 구성된 조절 네트워크를 S-system을 이용하여 모델링하였다. 이를 통해 각 유전자들의 발현 데이터로부터 파라미터들을 진화 연산을 통해 예측하고, 각 유전자들의 발현에 대한 시뮬레이션 결과를 보여준다. 예측된 결과와 실제 데이터의 비교는 전체적으로 패턴이 서로 유사함을 보여주고 있다.

• Journal of Life Science
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• v.33 no.1
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• pp.64-72
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• 2023

Despite several advances in identification of cardiac transcription factors, there are still needs to find new bioactive molecules that promote cardiomyogenesis from stem cells to highly efficient myocardial differentiation. We analyzed Illumina expression microarray data of mouse embryonic stem cells (mESCs)-derived cardiomyocytes. 276 genes were upregulated (≥ 4fold) in mESCs-derived cardiomyocytes compared undifferentiated ESCs. Secreted phosphoprotein 2 (Spp2) is one of candidates and is known to inhibit bone morphogenetic protein 2 (BMP2) signal transduction as a pseudoreceptor for BMP2. However, its function in cardiomyogenesis is unknown. We confirmed that Spp2 expression increased during the differentiation into functional cardiomyocytes using mESCs, TC-1/Kh2 and E14. Interestingly, Spp2 secretion transiently increased 3 days after formation of embryoid bodies (EBs), indicating that the extracellular secretion of Spp2 is involved in the differentiation of ESCs into cardiomyocytes. To characterize Spp2, we performed experiments using the C2C12 mouse myoblast cell line, which has the property of shifting the differentiation pathway from myoblastic to osteoblastic by treatment with BMP2. Similar to the differentiation of ESCs, transcription of Spp2 increased as C2C12 myoblasts differentiated into myotubes. In particular, Spp2 secretion increased dramatically in the early stage of differentiation. Furthermore, treatment with Spp2-Flag recombinant protein promoted the differentiation of C2C12 myoblasts into myotubes. Taken together, we suggest a novel bioactive protein Spp2 that differentiates ESCs into cardiomyocytes. This may be useful for understanding the molecular pathways of cardiomyogenesis and for experimental or clinical promotion of stem cell therapy for ischemic heart diseases.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2006.02a
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• pp.109-114
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• 2006

최근 Human 지놈 프로젝트를 포함한 다양한 종의 지놈 프로젝트가 수행되고 수많은 지놈정보가 생산되고 있으며 이를 해석하고 서로 연관성를 찾기 위한 다양한 연구가 진행되고 있다. 즉 최신 생명공학과 관련된 연구방향이 DNA의 구조적 해석에서 기능 해석과 유전자들의 상호연관성을 규명하는 방향으로 변화하고 있으며 이를 위한 강력한 도구로서 DNA microarray (DNA chip)는 방대한 양의 지놈 정보를 이용하여 단시간에 대량으로 고속처리하여 효율적으로 유전자 기능을 분석할 수 있는 주목받고 있는 방법이다. DNA microarray 실험과 분석에 있어 데이터분석, 재현성, 종간의 비교, 확인실험 및 비용 등의 문제가 있지만 유전자발현양상 데이터로부터 정확한 환자의 예후를 예측할 수 있는 비교적 적은 유전자 그룹의 진단마커를 찾거나, 하나의 유전자가 아니라 mouse 전체 지놈의 유전자발현 패턴을 인간의 암을 위시한 각종 질병 연구를 위한 발현 신호나 변화 등을 발견하여 신약개발 등에 활용하고자 하는 시도가 활발히 진행되고 있다. 서로 다른 종간에 비슷한 phenotype의 유전자발현도 진화적으로 보존되었다는 전제 하에서 지놈 sequence의 비교연구가 가능하고 DNA microarray 발현 데이터에 근거하여 독립적으로 각 종간의 유전자발현패턴을 비교함으로써 난치병 등을 새롭게 분류할 수 있다. 즉, 암세포 등에서 유전자발현 양상은 유전학적, 환경적 alteration들이 잘 반영되어 있다고 간주하고, 이러한 양상을 바탕으로 인간의 암을 위시한 다양한 질병 연구를 위한 최적의 mouse 모델을 찾을 수 있고, 이는 결국 새로운 치료 방법 개발이나 맞춤의학 실현에 중요한 역할을 할 것으로 기대된다. 특히 pathway 타겟으로 하는 치료를 위해서는 Human-mouse 비교를 통한 발현 신호를 찾는 것이 진단에서는 매우 유용한 방법이다. 이를 위한 고성능의 분석방법이나 시스템의 개발이 중요하게 된다.. 관류의 정도와 조영증강정도를 중심으로 관류 MR 영상소견과 조직학적 소견을 관련지어 분석하였다. 결과: 조영증강 T1강조MR영상에서 환상조영증강을 보이는 다형성 교보세포종 2예에서는 변연부 외륜이 고관류를, 중심부의 괴사부위는 저관류로 나타났다. 저등급 교종은 경계가 불분명한 저관류부위로 보였다. 뇌농양 2예는 변연부 외륜이 경도의 고관류를, 중심부는 저관류로 나타났다. 뇌수막종은 미만성의 균일한 중등도 혹은 고도의 고관류로 보였으며, 임파종과 배아종은 경계가 명확한 저관류부위로 나타났다. 신경세포종은 종괴\ulcorner 일부에 중등도 혹은 고도의 고관류부위가 관찰되었고, 전이암은 다수병변중 일부에서 중등도의 고관류를 보였다. 방사선괴사는 저관류부위내에 국소적 고관류부위를 보였다. 결론: 관류 MR영상은 뇌종양의 관류상태를 비교적 잘 반영하며, 조직학적 특성을 예측하는데에 도움을 주 수 있을 것으로 기대된다. 뇌종야에서의 관류MR영상의 분명한 역할을 규명하기 위해서는 앞으로 더 많은 임상적 연구가 필요할 것으로 생각된다.조증 환자의 자극성 전타액내 lactobacilli양은 peroxidase system을 함유한 세치제를 사용한 군에서 대조군에 비해 상대적으로 낮게 나타났으나(p = 0.067) 통계학적 유의성은 없었다.같은 예에서 찾아 볼 수 있다. 첫째, 발음상으로 동사의 변화형에서 "porte[$p{\jmath}rte$](들다: 현재형), porte[$p{\jmath}rte$](과거분사형), porta[$p{\jmath}rte$](단순과거형)"등이 대립되며, 이휘 "Porto[$p{\jmath}rte$](포르토)"와도 대립된다. 둘째, 어휘적 대립 "le haut[$l{\partial}o$](위)/l'eau[lo](물)"와 형태론적 대립 "le[$l{\partial}$](정관사, 남성단수)/l

• The Journal of the Acoustical Society of Korea
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• v.39 no.2
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• pp.137-142
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• 2020

Many studies based on I-vector have been conducted in a variety of environments, from text-dependent short-utterance to text-independent long-utterance. In this paper, we propose a speaker verification system employing a combination of I-vector with Probabilistic Linear Discriminant Analysis (PLDA) and speaker embedding of Long Short Term Memory (LSTM) with attention mechanism in far-field and noisy environments. The LSTM model's Equal Error Rate (EER) is 15.52 % and the Attention-LSTM model is 8.46 %, improving by 7.06 %. We show that the proposed method solves the problem of the existing extraction process which defines embedding as a heuristic. The EER of the I-vector/PLDA without combining is 6.18 % that shows the best performance. And combined with attention-LSTM based embedding is 2.57 % that is 3.61 % less than the baseline system, and which improves performance by 58.41 %.

• The Journal of the Acoustical Society of Korea
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• v.38 no.6
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• pp.703-709
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• 2019

This paper proposes speech recognition systems employing Convolutional Neural Network (CNN) and Long Short Term Memory (LSTM) structures combined with Hidden Markov Moldel (HMM) to effectively recognize the speech of VeloPharyngeal Insufficiency (VPI) patients, and compares the recognition performance of the systems to the Gaussian Mixture Model (GMM-HMM) and fully-connected Deep Neural Network (DNNHMM) based speech recognition systems. In this paper, the initial model is trained using normal speakers' speech and simulated VPI speech is used for generating a prior model for speaker adaptation. For VPI speaker adaptation, selected layers are trained in the CNN-HMM based model, and dropout regulatory technique is applied in the LSTM-HMM based model, showing 3.68 % improvement in recognition accuracy. The experimental results demonstrate that the proposed LSTM-HMM-based speech recognition system is effective for VPI speech with small-sized speech data, compared to conventional GMM-HMM and fully-connected DNN-HMM system.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.119-124
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• 1997

Purpose: To assess the utility of magnetic resonance(MR) cerebral blood volume (CBV) map in the evaluation of brain tumors. Materials and Methods: We performed perfusion MR imaing preoperatively in the consecutive IS patients with intracranial masses(3 meningiomas, 2 glioblastoma multiformes, 3 low grade gliomas, 1 lymphoma, 1 germinoma, 1 neurocytoma, 1 metastasis, 2 abscesses, 1 radionecrosis). The average age of the patients was 42 years (22yr -68yr), composed of 10 males and S females. All MR images were obtained at l.ST imager(Signa, CE Medical Systems, Milwaukee, Wisconsin). The regional CBV map was obtained on the theoretical basis of susceptibility difference induced by first pass circulation of contrast media. (contrast media: IScc of gadopentate dimeglumine, about 2ml/sec by hand, starting at 10 second after first baseline scan). For each patient, a total of 480 images (6 slices, 80 images/slice in 160 sec) were obtained by using gradient echo(CE) single shot echo-planar image(EPI) sequence (TR 2000ms, TE SOms, flip angle $90^{\circ}$, FOV $240{\times}240mm,{\;}matrix{\;}128{\times}128$, slice-thick/gap S/2.S). After data collection, the raw data were transferred to CE workstation and rCBV maps were generated from the numerical integration of ${\Delta}R2^{*} on a voxel by voxel basis, with home made software (${\Delta}R2^{*}=-ln (S/SO)/TE). For easy visual interpretation, relative RCB color coding with reference to the normal white matter was applied and color rCBV maps were obtained. The findings of perfusion MR image were retrospectively correlated with Cd-enhanced images with focus on the degree and extent of perfusion and contrast enhancement. Results: Two cases of glioblastoma multiforme with rim enhancement on Cd-enhanced Tl weighted image showed increased perfusion in the peripheral rim and decreased perfusion in the central necrosis portion. The low grade gliomas appeared as a low perfusion area with poorly defined margin. In 2 cases of brain abscess, the degree of perfusion was similar to that of the normal white matter in the peripheral enhancing rim and was low in the central portion. All meningiomas showed diffuse homogeneous increased perfusion of moderate or high degree. One each of lymphoma and germinoma showed homogenously decreased perfusion with well defined margin. The central neurocytoma showed multifocal increased perfusion areas of moderate or high degree. A few nodules of the multiple metastasis showed increased perfusion of moderate degree. One radionecrosis revealed multiple foci of increased perfusion within the area of decreased perfusion. Conclusion: The rCBV map appears to correlate well with the perfusion state of brain tumor, and may be helpful in discrimination between low grade and high grade gliomas. The further study is needed to clarify the role of perfusion MR image in the evaluation of brain tumor.

• Analytical Science and Technology
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• v.24 no.6
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• pp.533-543
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• 2011

The hERG (human ether-a-go-go related gene) ion channel is a main factor for cardiac repolarization, and the blockade of this channel could induce arrhythmia and sudden death. Therefore, potential hERG ion channel inhibitors are now a primary concern in the drug discovery process, and lots of efforts are focused on the minimizing the cardiotoxic side effect. In this study, $IC_{50}$ data of 202 organic compounds in HEK (human embryonic kidney) cell from literatures were used to develop predictive 2D-QSAR model. Multiple linear regression (MLR), Support Vector Machine (SVM), and artificial neural network (ANN) were utilized to predict inhibition concentration of hERG ion channel as machine learning methods. Population based-forward selection method with cross-validation procedure was combined with each learning method and used to select best subset descriptors for each learning algorithm. The best model was ANN model based on 14 descriptors ($R^2_{CV}$=0.617, RMSECV=0.762, MAECV=0.583) and the MLR model could describe the structural characteristics of inhibitors and interaction with hERG receptors. The validation of QSAR models was evaluated through the 5-fold cross-validation and Y-scrambling test.