• 한국멀티미디어학회논문지
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• 제12권2호
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• pp.290-299
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• 2009

진화하는 인공신경망은 인공지능분야와 게임 NPC의 지능 설계 분야에서 새롭게 각광을 받고 있다. 하지만 진화하는 인공신경 망을 이용하여 게임 NPC의 지능을 설계할 때 인공신경 망의 구조가 복잡함에 따라 진화와 평가에 필요한 연산량이 크며 또한 적절한 적합도 함수를 설계하지 못하면 지능적인 NPC를 설계할 수 없는 등의 문제점을 가지고 있다. 본 논문에서는 이러한 문제들을 해결하고자 동적 상태 진화 인공신경망을 제안한다. 동적 상태 진화 인공신경망은 전통적인 진화하는 인공신경망 알고리즘에 기반하여 진화 과정에서 신경망의 신경세포들 사이의 시냅스를 제거(disabled) 하거나 고정(fixed)시키는 방법을 통하여 진화와 평가과정에 소모되는 연산량을 줄이는 알고리즘이다. 본 논문은 Darwin Platform 을 테스트 베드로 축구게임 NPC의 지능 설계를 통하여 제안하는 방법의 유용성을 검증한다.

• Biomolecules & Therapeutics
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• 제26권5호
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• pp.439-445
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• 2018

T-type calcium channels are low voltage-activated calcium channels that evoke small and transient calcium currents. Recently, T-type calcium channels have been implicated in neurodevelopmental disorders such as autism spectrum disorder and neural tube defects. However, their function during embryonic development is largely unknown. Here, we investigated the function and expression of T-type calcium channels in embryonic neural progenitor cells (NPCs). First, we compared the expression of T-type calcium channel subtypes (CaV3.1, 3.2, and 3.3) in NPCs and differentiated neural cells (neurons and astrocytes). We detected all subtypes in neurons but not in astrocytes. In NPCs, CaV3.1 was the dominant subtype, whereas CaV3.2 was weakly expressed, and CaV3.3 was not detected. Next, we determined CaV3.1 expression levels in the cortex during early brain development. Expression levels of CaV3.1 in the embryonic period were transiently decreased during the perinatal period and increased at postnatal day 11. We then pharmacologically blocked T-type calcium channels to determine the effects in neuronal cells. The blockade of T-type calcium channels reduced cell viability, and induced apoptotic cell death in NPCs but not in differentiated astrocytes. Furthermore, blocking T-type calcium channels rapidly reduced AKT-phosphorylation (Ser473) and $GSK3{\beta}$-phosphorylation (Ser9). Our results suggest that T-type calcium channels play essential roles in maintaining NPC viability, and T-type calcium channel blockers are toxic to embryonic neural cells, and may potentially be responsible for neurodevelopmental disorders.

• Experimental and Molecular Medicine
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• 제50권11호
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• pp.5.1-5.14
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• 2018

Oxidative stress-induced mitochondrial dysfunction is implicated in the pathogenesis of intervertebral disc degeneration (IVDD). Sirtuin 3 (SIRT3), a sirtuin family protein located in mitochondria, is essential for mitochondrial homeostasis; however, the role of SIRT3 in the process of IVDD has remained elusive. Here, we explored the expression of SIRT3 in IVDD in vivo and in vitro; we also explored the role of SIRT3 in senescence, apoptosis, and mitochondrial homeostasis under oxidative stress. We subsequently activated SIRT3 using honokiol to evaluate its therapeutic potential for IVDD. We assessed SIRT3 expression in degenerative nucleus pulposus (NP) tissues and oxidative stress-induced nucleus pulposus cells (NPCs). SIRT3 was knocked down by lentivirus and activated by honokiol to determine its role in oxidative stress-induced NPCs. The mechanism by which honokiol affected SIRT3 regulation was investigated in vitro, and the therapeutic potential of honokiol was assessed in vitro and in vivo. We found that the expression of SIRT3 decreased with IVDD, and SIRT3 knockdown reduced the tolerance of NPCs to oxidative stress. Honokiol ($10{\mu}M$) improved the viability of NPCs under oxidative stress and promoted their properties of anti-oxidation, mitochondrial dynamics and mitophagy in a SIRT3-dependent manner. Furthermore, honokiol activated SIRT3 through the AMPK-PGC-$1{\alpha}$ signaling pathway. Moreover, honokiol treatment ameliorated IVDD in rats. Our study indicated that SIRT3 is involved in IVDD and showed the potential of the SIRT3 agonist honokiol for the treatment of IVDD.

• 한국발생생물학회지:발생과생식
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• 제10권3호
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• pp.169-175
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• 2006

전세계적으로 널리 복용되고 있음에도 불구하고 인삼이 중추신경계에 미치는 효과에 대한 세포수준에서의 증거는 별로 없다. 따라서 본 연구자들은 지금까지 보고된 30여종 이상의 ginsenosides 중에서 인삼 효과의 주된 활성성분으로 알려져 있는 Rb1과 Rg1을 이용해 해마신경전구세포의 분화와 증식에 미치는 효과를 연구하였다. 증식실험결과 Rb1과 Rg1을 3일 동안 해마신경전구세포에 처리하면 대조군에 비해 BrdU(+)세포수가 상당히 감소한 반면에 분화조건에서 Rb1과 Rg1을 처리했을 때는 신경세포특이적인 MAP2 단백질을 발현하는 세포수가 증가하였다. 전구세포의 신경세포로의 분화 결정에 관여한다고 잘 알려져 있는 proneural 전사인자인 Ngn1과 Hes1 유전자의 발현양상도 대조군에 비해 증가하였다. 따라서 본 연구 결과, ginsenoside Rb1과 Rg1은 해마신경전구세포의 증식을 감소시키고 대신 신경세포로의 분화를 촉진시킴으로써 해마신경발생에 관여함을 보여준다.

• The Korean Journal of Physiology and Pharmacology
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• 제22권6호
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• pp.679-688
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• 2018

Autism spectrum disorders (ASDs) are neurodevelopmental disorders that share behavioral features, the results of numerous studies have suggested that the underlying causes of ASDs are multifactorial. Behavioral and/or neurobiological analyses of ASDs have been performed extensively using a valid model of prenatal exposure to valproic acid (VPA). Abnormal synapse formation resulting from altered neurite outgrowth in neural progenitor cells (NPCs) during embryonic brain development has been observed in both the VPA model and ASD subjects. Although several mechanisms have been suggested, the actual mechanism underlying enhanced neurite outgrowth remains unclear. In this study, we found that VPA enhanced the expression of brain-derived neurotrophic factor (BDNF), particularly mature BDNF (mBDNF), through dual mechanisms. VPA increased the mRNA and protein expression of BDNF by suppressing the nuclear expression of methyl-CpG-binding protein 2 (MeCP2), which is a transcriptional repressor of BDNF. In addition, VPA promoted the expression and activity of the tissue plasminogen activator (tPA), which induces BDNF maturation through proteolytic cleavage. Trichostatin A and sodium butyrate also enhanced tPA activity, but tPA activity was not induced by valpromide, which is a VPA analog that does not induce histone acetylation, indicating that histone acetylation activity was required for tPA regulation. VPA-mediated regulation of BDNF, MeCP2, and tPA was not observed in astrocytes or neurons. Therefore, these results suggested that VPA-induced mBDNF upregulation was associated with the dysregulation of MeCP2 and tPA in developing cortical NPCs.

• 한국멀티미디어학회논문지
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• 제11권9호
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• pp.1258-1266
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• 2008

대개의 게임 플레이어들은 정해진 패턴대로만 행동하는 NPC(Non-Player Character)보다 사람 플레이어와 상호작용할 때 더욱 큰 만족을 얻는다. 하지만 항상 사람 플레이어를 상대할 수 있는 것은 아니기 때문에 다양한 게임 플레이어에 맞추어 행동할 수 있는 적응형 NPC가 필요하다. 본 논문에서는 FSM(Finite State Machine)을 이용하여 적응형 NPC를 생성하는 기법을 제안한다. 이 기법은 행동 데이터베이스의 행동 정보를 이용하여 FSM을 구성하고, 게임을 진행하는 동안 FSM의 종합 효율값이 목표 효율값으로 접근하도록 실시간으로 FSM을 갱신하는 것을 반복한다. 이 과정에서 NPC는 플레이어에게 적응한다. 실험은, 제안한 기법을 적용한 2D 게임을 제작하여 목표 효율값을 다양하게 설정하여 진행하였다. 실험 결과로, 게임이 진행되면서 종합 효율값이 목표 효율값으로 접근하는 것을 볼 수 있었다. 이는 NPC가 플레이어에게 적응하여 적응형 NPC가 생성됨을 의미하는 것이다.

• 한국게임학회 논문지
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• 제14권5호
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• pp.127-136
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• 2014

게임 NPC(Non Player Character)는 게임 플레이어와 대전 또는 협력함으로써 게임의 재미를 증가시키는 중요한 요소이다. 대부분 기존 게임에서 제공되는 NPC 인공지능은 FSM(Finite State Machine)으로 제작되어 행동 패턴이 정해져 있고 능력이 동일한 특징을 갖고 있다. 따라서 이러한 특징을 갖는 NPC들과 대전하는 플레이어는 창조적인 게임 플레이를 진행하는 것이 어려울 수 있다. 본 논문은 이 문제점을 개선하기 위하여 실제 생활에서 늑대들이 먹이를 사냥하는 행동 모델을 게임 NPC의 행동 모델로 제작하고 이를 평가하기 위한 것이다. 이를 위하여 첫째, 실세계에서 늑대들이 먹이를 포획하기 위한 행동 상태들을 조사 연구한다. 둘째, 이 행동 상태들을 Unity3D 엔진을 이용하여 구현한다. 셋째, 구현된 NPC들의 상태 전이 비율과 실세계의 NPC들의 상태 전이 비율, 일반적인 게임 NPC의 상태 전이 비율을 비교한다. 비교 결과, 구현된 NPC들의 상태 전이 비율은 실세계의 상태 전이 비율과 비슷함을 보인다. 이는 구현된 NPC들의 행동 패턴이 실세계의 늑대 사냥 행동 패턴과 유사함을 의미하는데, 이렇게 함으로써 플레이어에게 보다 증가된 사용자 경험을 제공할 수 있다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권10호
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• pp.5637-5644
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• 2013

The definite molecular mechanisms underlying the genesis of nasopharyngeal carcinomas (NPCs) remain to be completely elucidated. miRNAs are small non-coding RNAs which are implicated in cell proliferation, apoptosis, and even carcinogenesis through negatively regulating gene expression post-transcriptionally. EBV was the first human virus found to express miRNAs. EBV-encoded BART-miRNAs and dysregulated cellular miRNAs are involved in carcinogenesis of NPC by interfering in the expression of viral and host cell genes related to immune responses and perturbing signal pathways of proliferation, apoptosis, invasion, metastasis and even radio-chemo-therapy sensitivity. Additional studies on the roles of EBV-encoded miRNAs and cellular miRNAs will provide new insights concerning the complicated gene regulated network and shed light on novel strategies for the diagnosis, therapy and prognosis of NPC.

• International Journal of Contents
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• 제2권3호
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• pp.18-21
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• 2006

Nowadays, many people enjoy playing games in computer. In this kind of game, people often meet NPC (Non Player Character). It is the virtual character in simplified form of real player and exits in most of current computer games. Various NPCs add the reality and atmosphere of the game as well as help players. There are several techniques to embody NPC, but developers generally use AI technique. This paper discusses some artificial intelligence techniques used in game contents. Especially this paper focuses on the AI techniques used in computer games in terms of the two main approaches, symbolic approach and sub-symbolic approach.

• Biomolecules & Therapeutics
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• 제26권6호
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• pp.608-615
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• 2018

Benzalkonium chloride, diazolidinyl urea, and imidazolidinyl urea are commonly used preservatives in cosmetics. Recent reports suggested that these compounds may have cellular and systemic toxicity in high concentration. In addition, diazolidinyl urea and imidazolidinyl urea are known formaldehyde (FA) releasers, raising concerns for these cosmetic preservatives. In this study, we investigated the effects of benzalkonium chloride, diazolidinyl urea, and imidazolidinyl urea on ROS-dependent apoptosis of rat neural progenitor cells (NPCs) in vitro. Cells were isolated and cultured from embryonic day 14 rat cortices. Cultured cells were treated with 1-1,000 nM benzalkonium chloride, and $1-50{\mu}M$ diazolidinyl urea or imidazolidinyl urea at various time points to measure the reactive oxygen species (ROS). PI staining, MTT assay, and live-cell imaging were used for cell viability measurements. Western blot was carried out for cleaved caspase-3 and cleaved caspase-8 as apoptotic protein markers. In rat NPCs, ROS production and cleaved caspase-8 expression were increased while the cell viability was decreased in high concentrations of these substances. These results suggest that several cosmetic preservatives at high concentrations can induce neural toxicity in rat brains through ROS induction and apoptosis.