• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.567-570
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• 2000

The condition of immobilization of the partially purified levan fructotransferase and the properties of the immobilized enzyme was investigated. Levan fructotransferase was immobilized on ${\kappa}\;-carrageenan$ beads by entrapment method. The optimal ${\kappa}\;-carrageenan$ concentration was obtained 2%(w/v) (or the matrix. At that time, immobilized enzymes(0.81 units) have relative low activity compare with soluble enzyme(7.7 units). To immobilized and soluble enzyme, optimal activity temperature and pH were measured $55^{\circ}C$, 6.0 in sodium phosphate buffer 20mM solution. If crosslinking agent was added, proper concentration was 0.5%(v/v). At $37^{\circ}C$, immobilized and soluble enzyme converted levan to oligofructose and DFA IV, and the conversion ratio was 32% and 61% at 60 hr.

• Sleep Medicine and Psychophysiology
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• v.15 no.1
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• pp.5-11
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• 2008

Sleep is an essential process maintaining the life cycle of the human. In parallel with physiological, cognitive, subjective, and behavioral changes that take place during the sleep, there are remarkable changes in the electroencephalogram (EEG) that reflect the underlying electro-physiological activity of the brain. However, analyzing EEG and relating the results to clinical observations is often very hard due to the complexity and a huge data amount. In this article, I introduce several linear and non-linear tools, developed to analyze a huge time series data in many scientific researches, and apply them to EEG to characterize various sleep states. In particular, the spectral analysis, detrended fluctuation analysis (DFA), and synchrony analysis are administered to EEG recorded during nocturnal polysomnography (NPSG) processes and daytime multiple sleep latency tests (MSLT). I report that 1) sleep stages could be differentiated by the spectral analysis and the DFA ; 2) the gradual transition from Wake to Sleep during the sleep onset could be illustrated by the spectral analysis and the DFA ; 3) electrophysiological properties of narcolepsy could be characterized by the DFA ; 4) hypnic jerks (sleep starts) could be quantified by the synchrony analysis.

• Journal of Periodontal and Implant Science
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• v.51 no.4
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• pp.239-253
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• 2021

Purpose: The single-flap approach (SFA) is a minimally invasive technique with limited mucoperiosteal flap elevation to gain access to the buccal/palatal aspects, thus limiting post-surgical complications. The purpose of the present study was to gain insights into the impact of the SFA over the double-flap approach (DFA) on periodontal flap treatment outcomes and patient compliance in terms of discomfort and time taken for surgical procedures. Methods: Twenty patients with persistent probing pocket depths of ≥5 mm were scheduled for the SFA (test site) and for the DFA (control site). All the clinical periodontal parameters were recorded at baseline, 3 months, and 6 months. Radiographic bone level (cone-beam computed tomography) was evaluated at baseline and 6 months. Patients' postoperative pain perception and wound healing were also assessed. Results: The SFA showed a significant reduction in periodontal pocket depth, gain in clinical attachment level (CAL), and gain in bone level when compared with the DFA. The SFA substantially improved wound healing and induced less postoperative pain than the DFA. Conclusions: The SFA resulted in substantial improvement in the composite outcome measures, as shown by a reduction in pocket depth with minimal gingival recession, gain in CAL, early wound healing, less postoperative discomfort, and better patient-centered outcomes.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.25-30
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• 2013

In this work, we investigate the statistical properties of gamma exposure rates using well-known analysis methods, such as Autocorrelation Function Analysis(ACF), Rescaled Range Analysis(R/S Analysis), and Detrended Fluctuation Analysis(DFA). Especially, DFA is an important method to reliably detect long-range correlations in non-stationary time series. Our data are measured by Gangneung regional radiation monitoring station over the period of 1998 to 2011. First, we find a crossover indicating two different governing regimes in fluctuations of gamma exposure rates. Within a year, they show a strong long-ranged memory while this property vanishes over the range of time period longer than one year. Second, our finding is very securely supported by a variety of analysis tools. Those tools yield many relevant exponents which satisfies the well known relation between them.

• Korean Journal of Biological Psychiatry
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• v.19 no.1
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• pp.65-69
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• 2012

Objectives : Much is still unknown about the neurophysiological mechanisms or dynamics of the sleep onset process. Detrended fluctuation analysis (DFA) is a new tool for the analysis of electroencephalography (EEG) that may give us additional information about electrophysiological changes. The purpose of this study is to analyze long-range correlations of electroencephalographic signals by DFA and their changes in the sleep onset process. Methods : Thirty channel EEG was recorded in 61 healthy subjects (male:female=34:27, age=$27.2{\pm}3.0$ years). The scaling exponents, alpha, were calculated by DFA and compared between four kinds of 30s sleep-wakefulness states such as wakefulness, transition period, early sleep, and late sleep (stage 1). These four states were selected by the distribution of alpha and theta waves in O1 and O2 electrodes. Results : The scaling exponents, alpha, were significantly different in the four states during sleep onset periods, and also varied with the thirty leads. The interaction between the sleep states and the leads was significant. The means (${\pm}$ standard deviation) of alphas for the states were 0.94 (${\pm}0.12$), 0.98 (${\pm}0.12$), 1.10 (${\pm}0.10$), 1.07 (${\pm}0.07$) in the wakefulness, transitional period, early sleep and late sleep state respectively. The mean alpha of anterior fifteen leads was greater than that of posterior fifteen leads, and the two regions showed the different pattern of changes of the alpha during the sleep onset periods. Conclusions : The characteristic findings in the sleep onset period were the increasing pattern of scaling exponent of DFA, and the pattern was slightly but significantly different between fronto-temporal and parieto-occipital regions. It suggests that the long-range correlations of EEG have a tendency of increasing from wakefulness to early sleep, but anterior and posterior brain regions have different dynamical process. DFA, one of the nonlinear analytical methods for time series, may be a useful tool for the investigation of the sleep onset period.

• The Korean Journal of Physiology and Pharmacology
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• v.21 no.6
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• pp.687-694
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• 2017

Plumbagin, a hydroxy 1,4-naphthoquinone compound from plant metabolites, exhibits anticancer, antibacterial, and antifungal activities via modulating various signaling molecules. However, its effects on vascular functions are rarely studied except in pulmonary and coronary arteries where NADPH oxidase (NOX) inhibition was suggested as a mechanism. Here we investigate the effects of plumbagin on the contractility of skeletal artery (deep femoral artery, DFA), mesenteric artery (MA) and renal artery (RA) in rats. Although plumbagin alone had no effect on the isometric tone of DFA, $1{\mu}M$ phenylephrine (PhE)-induced partial contraction was largely augmented by plumbagin (${\Delta}T_{Plum}$, 125% of 80 mM KCl-induced contraction at $1{\mu}M$). With relatively higher concentrations (>$5{\mu}M$), plumbagin induced a transient contraction followed by tonic relaxation of DFA. Similar biphasic augmentation of the PhE-induced contraction was observed in MA and RA. VAS2870 and GKT137831, specific NOX4 inhibitors, neither mimicked nor inhibited ${\Delta}T_{Plum}$ in DFA. Also, pretreatment with tiron or catalase did not affect ${\Delta}T_{Plum}$ of DFA. Under the inhibition of PhE-contraction with L-type $Ca^{2+}$ channel blocker (nifedipine, $1{\mu}M$), plumbagin still induced tonic contraction, suggesting $Ca^{2+}$-sensitization mechanism of smooth muscle. Although ${\Delta}T_{Plum}$ was consistently observed under pretreatment with Rho A-kinase inhibitor (Y27632, $1{\mu}M$), a PKC inhibitor (GF 109203X, $10{\mu}M$) largely suppressed ${\Delta}T_{Plum}$. Taken together, it is suggested that plumbagin facilitates the PKC activation in the presence of vasoactive agonists in skeletal arteries. The biphasic contractile effects on the systemic arteries should be considered in the pharmacological studies of plumbagin and 1,4-naphthoquinones.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2491-2496
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• 2010

The DFA(detrended fluctuation analysis) which is included the correlation property of the EEG is used to analysis the depth of anesthesia. We studied ASA I or II adult patients supported by the society of anesthesiologists. Patients with history of dementia and neurological disorder are excluded. Average age is $48.9{\pm}10.9$ old, average weight is $57.1{\pm}8.2$ kg and average hight is $158{\pm}6.6$cm of the patients under the operation. Anesthesia medicine is Sevoflurane and the stages of anesthesia are 6 stages, that is pre-operation, induction, right after induction, stop the medicine and post-operation. Among the scaling exponent ${\alpha}1$, ${\alpha}2$, ${\alpha}3$ we know that ${\alpha}1$, ${\alpha}3$, were well appeared to discriminate pre-operation, induction, right after induction, stop the medicine and post-operation. So we confirmed that the parameters is useful to the depth of anesthesia.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.17-24
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• 2010

A differential fault attack(DFA) is one of the most efficient side channel attacks on block ciphers. Almost all block ciphers, such as DES, AES, ARIA, SEED and so on., have been analysed by this attack. In the case of the known DFAs on SEED, the attacker induces permanent faults on a whole left register of round 16. In this paper, we analyse SEED against DFA with differential characteristics and addition-XOR characteristics of the round function of SEED. The fault assumption of our attack is that the attacker induces 1-bit faults on a particular register. By using our attack, we can recover last round keys and the master key with about $2^{32}$ simple arithmetic operations. It can be simulated on general PC within about a couple of second.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.72-80
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• 2002

DFA (Design for assembly) is a design philosophy for improving product designs for simpler or less costly assembly operations. This paper proposes a new DFA methodology that can estimate the standard assembly time and evaluate the assemblablity of parts. We select some determining and influencing factors related with assembly process, and estimate the assembly time using motion analysis. By the levels of the determining and influencing factors, the assemblability is evaluated, and finally, the tables that include the time and score of assembly is suggested.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.525-528
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• 2005

원시 프로그램에 대한 컴파일 과정 중 최적화 단계에서는 프로그램의 실행 속도를 개선시키고 코드 크기를 줄일 수 있는 다양한 최적화 기법을 수행한다. 특히, 핍홀 ��적화는 비효율적인 명령어의 순서를 구별해 내고 연속되는 명령어의 순서를 의미적으로 동등하면서 좀 더 효율적인 코드로 개선하는 방법이다. 최적화 패턴 매칭 방법 중 스트링 패턴 매칭 방법은 중간 코드에 대응하는 최적의 패턴을 찾기 위한 방법으로 과다한 최적화 패턴 검색 시간으로 비효율적이고, 트리 패턴 매칭은 패턴 결정시 중복 비교가 발생할 수 있으며, 코드의 트리 구성에 많은 비용이 드는 단점을 가지고 있는 방법들이다. 본 논문에서는 기존의 최적화 방법들의 단점을 극복하기 위한 방법으로 DFA(Deterministic Finite Automata)를 이용한 코드 최적화 방법을 제안한다. 이 방법은 다른 패턴 매칭 기법보다 오토마타(Automata)로 구성하기 때문에 비용은 적어지고, 오토마타를 통해 결정적으로 패턴이 확정됨에 따른 패턴 선택 비용이 줄어들며, 최적화 패턴 검색 시간도 빨라지는 효율적인 방법이다.