• 한국결정성장학회지
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• 제7권4호
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• pp.560-566
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• 1997

Seeded vapor transport법에 의해 성장된 ZnSe 결정내에서 전위거동을 살펴보았다. (111)과 (100) ZnSe wafer의 etch pit 형상을 관찰하였고 성장된 결정이 높은 전위밀도를 가지면 전위들이 lineage와 cellular 두 가지 형태로 배열됨을 알았다. Seed로부터 측방성장된 부위에서 전위밀도의 변화는 없었으나 수직 성장방향으로는 전위밀도가 감소하였고, 같은 wafer내에서 전위밀도는 wafer center 지역의 전위밀도가 edge부위의 전위밀도 보다 낮았다. 성장된 결정의 평균 전위밀도는 $4{\times}10^4 /\textrm{cm}^2$이었다.

• 한국멀티미디어학회논문지
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• 제10권12호
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• pp.1726-1732
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• 2007

The rapid proliferation of wireless networks and mobile computing applications has changed the landscape of network security. Anomaly detection is a pattern recognition task whose goal is to report the occurrence of abnormal or unknown behavior in a given system being monitored. This paper presents an efficient rough set based anomaly detection method that can effectively identify a group of especially harmful internal attackers - masqueraders in cellular mobile networks. Our scheme uses the trace data of wireless application layer by a user as feature value. Based on this, the used pattern of a mobile's user can be captured by rough sets, and the abnormal behavior of the mobile can be also detected effectively by applying a roughness membership function with the age of the user profile. The performance of the proposed scheme is evaluated by using a simulation. Simulation results demonstrate that the anomalies are well detected by the proposed scheme that considers the age of user profiles.

• Journal of the Korean Data and Information Science Society
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• 제18권2호
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• pp.315-326
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• 2007

The rapid proliferation of wireless networks and mobile computing applications has changed the landscape of network security. Anomaly detection is a pattern recognition task whose goal is to report the occurrence of abnormal or unknown behavior in a given system being monitored. This paper presents a dynamic anomaly detection scheme that can effectively identify a group of especially harmful internal masqueraders in cellular mobile networks. Our scheme uses the trace data of wireless application layer by a user as feature value. Based on the feature values, the use pattern of a mobile's user can be captured by rough sets, and the abnormal behavior of the mobile can be also detected effectively by applying a roughness membership function with both the age of the user profile and weighted feature values. The performance of our scheme is evaluated by a simulation. Simulation results demonstrate that the anomalies are well detected by the proposed dynamic scheme that considers the age of user profiles.

• International Journal of Computer Science & Network Security
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• 제22권7호
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• pp.199-205
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• 2022

The extensive growth in data rate demand by the smart gadgets and mobile broadband application services in wireless cellular networks. To achieve higher data rate demand which leads to aggressive frequency reuse to improve network capacity at the price of Inter Cell Interference (ICI). Fractional Frequency Reuse (FFR) has been recognized as an effective scheme to get a higher data rate and mitigate ICI for perfect geometry network scenarios. In, an irregular geometric multicellular network, ICI mitigation is a challenging issue. The purpose of this paper is to develop distributed dynamic power allocation scheme for FFR based on game theory to mitigate ICI. In the proposed scheme, each cell region in an irregular multicellular scenario adopts a self-less behavior instead of selfish behavior to improve the overall utility function. This proposed scheme improves the overall data rate and mitigates ICI.

• Molecules and Cells
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• 제40권3호
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• pp.186-194
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• 2017

A brain-enriched secreting signal peptide, NELL2, has been suggested to play multiple roles in the development, survival, and activity of neurons in mammal. We investigated here a possible involvement of central NELL2 in regulating feeding behavior and metabolism. In situ hybridization and an immunohistochemical approach were used to determine expression of NELL2 as well as its colocalization with proopiomelanocortin (POMC) and neuropeptide Y (NPY) in the rat hypothalamus. To investigate the effect of NELL2 on feeding behavior, 2 nmole of antisense NELL2 oligodeoxynucleotide was administered into the lateral ventricle of adult male rat brains for 6 consecutive days, and changes in daily body weight, food, and water intake were monitored. Metabolic state-dependent NELL2 expression in the hypothalamus was tested in vivo using a fasting model. NELL2 was noticeably expressed in the hypothalamic nuclei controlling feeding behavior. Furthermore, all arcuatic POMC and NPY positive neurons produced NELL2. The NELL2 gene expression in the hypothalamus was up-regulated by fasting. However, NELL2 did not affect POMC and NPY gene expression in the hypothalamus. A blockade of NELL2 production in the hypothalamus led to a reduction in daily food intake, followed by a loss in body weight without a change in daily water intake in normal diet condition. NELL2 did not affect short-term hunger dependent appetite behavior. Our data suggests that hypothalamic NELL2 is associated with appetite behavior, and thus central NELL2 could be a new therapeutic target for obesity.

• 한국지능시스템학회논문지
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• 제12권1호
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• pp.19-26
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• 2002

자율이동로봇의 센서-모터 제어기를 구축하는데 있어 로봇의 기계적인 부분과 제어기 부분을 조화시키는 것이나 외부환경과 로봇의 상호작용을 처리하는 것 등이 가장 큰 문제점이다. 이러한 문제점들을 해결하기 위해서 진화적 접근방법이 많이 사용되고 있다. 이전 연구에서는 이러한 연구선상에서 셀룰라 오토마타 기반 신경망인 CAM-Brain을 이동로봇 제어기로 진화시켰다. 그러나, 하나의 모듈로 이루어진 제어기로는 복잡한 행동을 하도록 만들기 어렵기 때문에 본 논문에서는 하위 수준의 간단한 행동을 하도록 진화된 모듈들을 결합하여 보다 상위 수준의 복잡한 행동을 하도록 하는 다중 모듈 결합방법을 제안한다. 실험결과, 간단한 행동들을 하도록 진화된 CAM-Brain 모듈들을 규칙기반 방법으로 결합하여 주어진 좀더 환경에 적응할 수 있는 제어기를 얻을 수 있었다.

• 정보처리학회논문지D
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• 제16D권3호
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• pp.327-338
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• 2009

마이크로어레이 데이터는 유전자의 집합이 어떠한 조건 혹은 샘플의 집합 하에서 얼마나 발현되는지를 수치화한 2차원 행렬 데이터이다. 바이클러스터는 마이크로어레이의 샘플의 부분 집합과 이 샘플 부분 집합 하에서 일정한 증감 패턴을 보이는 유전자의 부분 집합을 말한다. 이렇게 같은 패턴을 보이는 유전자의 부분 집합은 일정한 정도의 유의 수준으로 비슷한 기능을 한다고 말할 수 있다. 따라서 바이클러스터링 알고리즘은 같은 기능에 연관된 유전자의 집합과, 이 기능이 발현되고 있는 조건의 집합을 밝혀내는데 있어서 매우 유용하다. 본 논문에서는 다항식 시간 복잡도를 유지하면서, 높은 기능적 상관관계를 가지는 바이클러스터를 밝혀 낼 수 있는 알고리즘을 제안한다. 이 알고리즘은 1) 마이크로어레이 데이터에 심한 노이즈가 있을 경우 패턴으로 인식하지 못하는 기존 알고리즘과 달리, 노이즈 레벨이 심하더라도 거시적으로 비슷한 모양을 보이는 패턴을 찾아내는 방식을 이용하여 숨어있는 패턴들을 찾아낼 수 있고, 2) 바이클러스터 상호간에 오버랩을 허용하며, 또한 다양성이 보장되는 복수의 바이클러스터를 찾아내며, 3) 찾아진 유전자 부분 집합의 기능적 상관관계가 매우 높은 특성을 지니고, 4) 유전자 및 샘플의 순서와 상관없이 결정적인(deterministic) 결과를 도출한다. 또한 본 논문에서는 알고리즘이 찾아낸 바이클러스터의 기능적 상관관계의 정도와, 비교 알고리즘이 찾아낸 바이클러스터의 기능적 상관관계의 정도를 유전자 온톨로지(Gene Ontology)를 통해서 측정함으로써 비교하고 있다.

• Molecules and Cells
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• 제28권3호
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• pp.209-213
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• 2009

Caenorhabditis elegans is a free living soil nematode and thus in its natural habitat, C. elegans encounters many different species of soil bacteria. Although some soil bacteria may be excellent sources of nutrition for the worm, others may be pathogenic. Thus, we undertook a study to understand how C. elegans can identify their preferred food using a simple behavioral assay. We found that there are various species of soil bacteria that C. elegans prefers in comparison to the standard laboratory E. coli strain OP50. In particular, two bacterial strains, Bacillus mycoides and Bacillus soli, were preferred strains. Interestingly, the sole feeding of these bacteria to wild type animals results in extended lifespan through the activation of the autophagic process. Further studies will be required to understand the precise mechanism controlling the behavior of identification and selection of food in C. elegans.

• Animal cells and systems
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• 제16권5호
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• pp.351-356
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• 2012

Food is important to any animal, and a large part of the behavioral repertoire is concerned with ensuring adequate nutrition. Two main nutritional sensations, hunger and satiety, produce opposite behaviors. Hungry animals seek food, increase exploratory behavior and continue feeding once they encounter food. Satiated animals decrease exploratory behavior, take rest, and stop feeding. The signals of hunger or satiety and their effects on physiology and behavior will depend not only on the animal's current nutritional status, but also on its experience and the environment in which the animal evolved. In our novel, nutritionally rich environment, improper control of appetite contributes to diseases from anorexia to the current epidemic of obesity. Despite extraordinary recent advances, genetic contribution to appetite control is still poorly understood partly due to lack of simple genetic model systems. In this review, we will discuss current understanding of molecular and cellular mechanisms by which animals regulate food intake depending on their nutritional status. Then, focusing on relatively less known muscarinic and cGMP signals, we will discuss how the molecular and behavioral aspects of hunger and satiety are conserved in a simple invertebrate model system, Caenorhabditis elegans so as for us to use it to understand the genetics of appetite control.

• 대한의생명과학회지
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• 제11권2호
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• pp.89-101
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• 2005

Obesity is increasing worldwide and has become a major health burden in Western societies affecting every third American and every fifth European. Obesity makes a major contribution to morbidity and mortality, predisposing individuals to cardiovascular disease and diabetes. Many new substances are currently being investigated for their usefulness in the pharmacotherapy of obesity. Most anti-obesity drugs can be divided into four groups: those that reduce food intake; those that alter metabolism; those that increase thermogenesis; and those that regulate hormone involved in feeding behavior. In this article we review these and other agents available in various countries for the treatment of obesity. Perhaps more importantly, we have focussed on areas of potential productivity in the future. Over the last 5 or so years, this impetus in obesity research has provided us with exciting new drugs targets involved in the regulation of feeding behavior and cellular mechanism involved in energy expenditure. Recent development in the quest for control of human obesity include the discovery of hormones, neuropeptides, receptors and transcription factors involved in feeding behavior, metabolic rate and adipocyte development. For developing new, perhaps even more specific pharmacological agents, further research is needed to understand the individual different genetic and physiological basis of obesity. It remains the hope of research scientists that in the not too distant future we shall see a new class of anti-obesity drugs arising logically from the molecular biology revolutions.