• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.219-220
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• 2007

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.429-432
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• 2000

Chitosan scaffold is widely applied to drug delivery and tissue engineering. We have developed chitosan scaffolds, with various pore size, by differing freezing temperature and duration of ultraviolet (UV) irradiation, for reconstructing skin equivalent. Chitosan scaffold was coated with type I collagen, fibronectin and basic fibroblast growth factor (bFGF) in various combinations and concentrations, to evaluate the effect of extracellular matrix (ECM) and bFGF on cell adhesion, growth and differentiation of dermal fibroblasts. Human dermal fibroblasts, isolated from newborn foreskin and passaged between 3 and 5, were seeded on the top of scaffolds and cultivated for 2 weeks. We examined the morphology and the secretion of ECM of fibroblasts using scanning electron microsopy (SEM) and histochemistry. A stellate morphology of fibroblasts were seen in all groups. The scaffold coated with either type I collagen and bFGF or type I collagen and fibronectin, however, showed the best condtion of dermal fibroblasts, in that the highest cell number and ECM secretion were seen. On the contrary, scaffolds coated with all three factors, type I collagen, bFGF and fibronectin, showed lower number of cells and ECM secretion than scaffolds with two factors. There was a tendency of dose-dependence in all three factors for fibroblast growth and ECM secretion. In conclusion, we may suggest that chitosan scaffold coated with either type I collagen/bFGF or type I collagen/fibronectin could provide more favorable environment for the growth and differentiation of dermal fibroblasts.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.86-92
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• 2016

In this study, we used a polymer deposition system, based on fused deposition modeling, to fabricate the 3D scaffold and then fabricated micro-pores on a 3D scaffold using a salt leaching method. Materials included polycaprolactone (PCL) and sodium chloride (NaCl). The 3D porous scaffolds were fabricated according to blending ratio such as PCL (70 wt%)/NaCl (30 wt%) and PCL (50 wt%)/NaCl (50 wt%). The 3D porous scaffolds were observed by scanning electron microscopy. The results showed that 3D porous scaffolds had a deposition width of $500{\mu}m$, contained a pore size of $500{\mu}m$ and below $100{\mu}m$. To evaluate the 3D porous scaffolds for bone tissue engineering, we carried out the cell proliferation experiment using a CCK-8 and a mechanical strength test using a universal testing machine. In summary, the 3D porous scaffold was found to be suitable for cancellous bone of human in accordance with the result of in-vitro cell proliferation and mechanical strength. Thus, a 3D porous scaffold could be a promising approach for effective bone regeneration.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.108-115
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• 2018

In bone tissue engineering, polycaprolactone (PCL) is one of the most widely used biomaterials to manufacture scaffolds as a synthetic polymer with biodegradability and biocompatibility. The polymer deposition system (PDS) with four axis heads, which can dispense bio-polymers, has been used in scaffold fabrication for tissue engineering applications. A dual-head deposition technology of PDS is an effective technique to fabricate 3D scaffolds. The electrospinning technology has been widely used to fabricate porous and highly interconnected polymer fibers. Thus, PDS can fabricate nanofiber-combined hybrid scaffolds using fused deposition modeling (FDM) and electrospinning methods. This study aims to fabricate nanofiber-combined scaffolds with uniform nanofibers using PDS. The PCL nanofibers were fabricated and evaluated according to the fabrication process parameters. PCL nanofibers were successfully fabricated when the applied voltage, tip-to-collector distance, flow rate, and solution concentration were 5 kV, 1 cm, 0.1 ml/h, and 8 wt%, respectively. The cell proliferation was evaluated according to the electrospinning time. Scanning electron microscopy was used to acquire images of the cross-sectioned hybrid scaffolds. The cell proliferation test of the PCL and nanofiber-combined hybrid scaffolds was performed using a CCK-8 assay according to the electrospinning time. The result of in-vitro cell proliferation using osteosarcoma MG-63 cells shows that the hybrid scaffold has good potential for bone regeneration.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5906-5914
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• 2013

Recently in Korea, the policy is being proceeded to build a intergenerational housing on artificial ground of railroad site for utilizing rental house. Due to narrow space of rail road site, suitable method have to be developed such as micropiles which is known as a method of a fast construction. However, If micropile is used as foundations for the super structure, construction cost is increases compared with other pile. Consequently, new concept micropile proposed to improve both bearing capacity and cost efficiency of general micropile. New concept micropile consists of waveform cement grout surrounding tread bar that formed by grouting the soil layer with jet grouting method as control the grout pressure and flow. The micropile with waveform is expected to decrease the construction cost by cut down pile length of general micropile. This paper examined the behavior of the new concept micropile with waveform subjected to axial load using two-dimensional axisymmetric numerical analyses method. According to the numerical result, there will cost effectiveness as the pile displacement decreased despite the length of waveform micropile is down about 5% from a general micropile under the same loading condition. Also, the effect of skin friction force which mobilized from the waveform of micropile appeared at relatively soft ground.

• Korean Journal of Cognitive Science
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• v.35 no.1
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• pp.23-48
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• 2024

Building human-aligned artificial intelligence (AI) for social support remains challenging despite the advancement of Large Language Models. We present a novel method, the Chain of Empathy (CoE) prompting, that utilizes insights from psychotherapy to induce LLMs to reason about human emotional states. This method is inspired by various psychotherapy approaches-Cognitive-Behavioral Therapy (CBT), Dialectical Behavior Therapy (DBT), Person-Centered Therapy (PCT), and Reality Therapy (RT)-each leading to different patterns of interpreting clients' mental states. LLMs without CoE reasoning generated predominantly exploratory responses. However, when LLMs used CoE reasoning, we found a more comprehensive range of empathic responses aligned with each psychotherapy model's different reasoning patterns. For empathic expression classification, the CBT-based CoE resulted in the most balanced classification of empathic expression labels and the text generation of empathic responses. However, regarding emotion reasoning, other approaches like DBT and PCT showed higher performance in emotion reaction classification. We further conducted qualitative analysis and alignment scoring of each prompt-generated output. The findings underscore the importance of understanding the emotional context and how it affects human-AI communication. Our research contributes to understanding how psychotherapy models can be incorporated into LLMs, facilitating the development of context-aware, safe, and empathically responsive AI.

• Journal of the Semiconductor & Display Technology
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• v.22 no.2
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• pp.40-44
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• 2023

The defect detection based on deep learning requires minimal loss and high accuracy to pinpoint product defects. In this paper, we confirm the loss rate of deep learning training based on disc-shaped artificial scaffold images. It is intended to compare the performance of Cross-Entropy functions used in object detection algorithms. The model was constructed using normal, defective artificial scaffold images and category cross entropy and sparse category cross entropy. The data was repeatedly learned five times using each loss function. The average loss rate, average accuracy, final loss rate, and final accuracy according to the loss function were confirmed.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.914-921
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• 2010

When industrial structures are constructed on soft ground, ground subsidence is occurred by problems of bearing capacity. To protect ground subsidence have to improve soft ground, and have to predict settlement estimation for reasonable construction. Artificial Neural Networks(ANN) is adopted for prediction of settlement of construction during the initial design. In the study, Artificial Neural Networks are applied to predict the settlement estimation of initial condition ground and ground improved by D.C.M method. Also, this study compares results of Artificial Neural Networks and results of continuum analysis using Mohr-Coulomb models. In result, settlements of initial condition ground decreased over 0.7 times. Also, by comparing ANN and continuum analysis, coefficient of determination was comparatively high value 0.79. Thought this study, it was confirmed that settlements of improvement ground is predicted using laboratory experiment data.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.33.1-33.1
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• 2011

이 논문에서는 비선형댐퍼를 이용한 광학탑재체 품질개선 방법에 대해 다루었다. 인공위성은 발사 시에 높은 진동하중에 견디어야 하며, 임무 수행 중에는 광학탑재체가 영상을 획득할 수 있도록 지지해주어야 한다. 그러나 인공위성은 자세제어, 데이터 송신, 탑재체 능동냉각을 위한 진동하중 가진 원을 보유하고 있어, 이를 광학탑재체 노출 시 영상품질이 저감되기 쉽다. 이 논문에서는 비선형 댐퍼를 이용해 발사 시에 높은 진동하중에 견디며, 발사 후에는 진동을 절연시켜 영상품질을 개선시키는 방법에 대한 연구를 수행하였다.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1259-1264
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• 2007

Microstereolithography technology has potential capability for fabrication of 3D microstructures. It evolved from conventional SLA which is one of the RP processes. In a microstereolithography process, 3D microstructures can be easily fabricated by continuously stacking 2D layer which is photopolymerized using a liquid prepolymer. Combination between biocompatible/biodegradable photocurable prepolymer and 3D complex fabrication in microstereolithography makes broad application areas such as medical, pharmaceutic, and bio devices. In particular, a 3D microneedle for transdermal drug delivery and a scaffold for tissue engineering are fabricated using this technology. In this paper, the authors address development of microstereolithography system adapted to large surface and fabrication of various microstructures. In addition, to apply human body we suggest a biodegradable 3D microneedle and a scaffold using biodegradable photocurable prepolymer.