• 대한물리의학회지
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• 제12권3호
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• pp.79-84
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• 2017

PURPOSE: The purpose of this study is to examine how task-oriented training focused on lower extremity strengthening can affect mobility function and postural stability. METHODS: The study's subjects included 10 children with cerebral palsy: 7 girls and 3 boys between the ages of 4 and 9 whose Gross Motor Functional Classification System (GMFCS) level was I or II. Their functional mobility was gauged using the Gross Motor Function Measurement (GMFM), and their postural stability was evaluated using a force platform. Participants received task-oriented training focused on lower extremity strengthening for 5 weeks. The study used a paired t-test to investigate the difference in mobility function and postural stability of children with cerebral palsy before and after the lower extremity strengthening exercise. RESULTS: The GMFM dimensions D (standing) (p<.02) and E (walking) (p<.001) improved significantly between the pre-test and post-test. A significant increase in the posturographic center of pressure (CoP) shift and surface area of the CoP were found overall between the pre-test and post-test (p<.001). CONCLUSION: The present study provides evidence that an 8-week task-oriented training focused on strengthening the lower extremities is an effective and feasible strategy for improving the mobility function and postural stability of children with cerebral palsy.

• 생명과학회지
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• 제23권5호
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• pp.669-675
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• 2013

본 연구에서는 Monascus sp. MK2가 생산하는 홍국색소의 안정성에 대하여 조사한 결과에서 광 안정성에서는 암 조건>자외선>실내(형광)>태양광 조건 순서로 안정하였으며, 온도에 대한 안정성은 온도가 증가하고 저장시간에 길어짐에 따라 홍국색소의 감소율 또한 비례적으로 증가하였고, pH에 대한 안정성은 전체적인 pH 영역에서 비교적 안정하였으며, 유기산 첨가에 대한 홍국색소의 안정성은 높은 것으로 생각되며, 합성 항산화제와 천연물 추출물 첨가시에는 안정성이 증대되는 것으로 조사되었다.

• Korean Journal of Mathematics
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• 제24권2호
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• pp.297-305
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• 2016

In this paper, by using fixed point theorem, we obtain the stability of the following functional equations $$f(pr,qs)+g(ps,qr)={\theta}(p,q,r,s)f(p,q)h(r,s)\\f(pr,qs)+g(ps,qr)={\theta}(p,q,r,s)g(p,q)h(r,s)$$, where G is a commutative semigroup, ${\theta}:G^4{\rightarrow}{\mathbb{R}}_k$ a function and f, g, h are functionals on $G^2$.

• 한국식품영양과학회지
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• 제45권7호
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• pp.996-1000
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• 2016

검정콩의 안토시아닌 색소의 안정성에 대한 유기산(succinic acid), 금속이온($Cu^{2+}$), ascorbic acid, 당류(sucrose) 및 pH의 영향을 $4^{\circ}C$ 및 $40^{\circ}C$에서 저장기간별로 살펴보았다. 모든 처리구에서 $4^{\circ}C$는 copigment 처리 여부에 관계없이 안정하였지만 $40^{\circ}C$에서는 copigment 처리구가 안정하였다. Succinic acid 처리는 $40^{\circ}C$에서 무처리에 비해 7~15% 안정성이 향상되었다. $Cu^{2+}$ 처리는 안토시아닌 색소와 반응하여 안정화에 효과가 있었으며, $4^{\circ}C$에서는 저장 8일차까지 100%로 유지되었다. Ascorbic acid 처리는 안정성을 저하했으며 $40^{\circ}C$에서는 무처리에 비해 64~72% 감소하였다. Sucrose 처리는 무처리에 비하여 효과가 작았으며 온도가 높을수록 안정성이 감소하였다. pH는 낮을수록 안정성이 증가하였으며 $4^{\circ}C$에 비하여 $40^{\circ}C$가 낮았다. 특히 pH 7에서는 급격히 감소하였다. 이러한 결과로부터 검정콩 안토시아닌 색소 저장 안정성 향상을 위해서는 온도, 유기산 및 pH 조절이 효과적이라고 판단된다.

• 한국표면공학회지
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• 제43권2호
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• pp.57-63
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• 2010

In this study, thermal stability of the mechanical properties of Ni-P-B and Ni-P-Fe layers electroplated on Alloy 600 material was evaluated by measuring their microhardness, tensile strength, and elongation after heat treatment at $325^{\circ}C$ and $400^{\circ}C$. According to the results, there was no noticeable change in microhardness of the two electrodeposits before and after heat treatment at the temperatures for 30 days. In the case of a Ni-P-B electrodeposit, ultimate tensile strength (UTS) slightly increases with heat treatment time, while its elongation decreases, showing good thermal stability in the mechanical properties at high temperature. On the other hand, UTS and elongation of Ni-P-Fe decrease with heat treatment time, which is very unusual observation. This result was attributed to the bad microstructure of Ni-P-Fe having many defects in the deposit formed early stage of an electroplating process and their redistribution to link to become large ones during heat treatment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.155-158
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• 1997

In this paper, we present new results concerning the relationship between the input-output and Lyapunov stability of nonlinear system possessing a periodic orbit. Definition of small-signal finite-gain L$\sub$p/ stability around periodic orbit is introduced. We show L$\sub$p/ stability of exponentially stable periodic orbit using quadratic Lyapunov functions for the periodic orbit. The L$\sub$2/ gain analysis is presented with Hamiltonian-Jacobi inequality along with an example.

• 패션비즈니스
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• 제22권3호
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• pp.30-38
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• 2018

Glycolic acid(GA) is well known the most effective cosmetic ingredient on the epidermal remodeling, accelerated desquamation and inhibitory effect on melanin synthesis. The various cosmetic formulations containing GA have not been reported in terms of stability. This study was to investigate the stability of three formulations(gel, cream, and ointment). The stability of obtained formulations was tested chemical and physical characteristics including the composition stability, hot-cool cycling, the variation of pH and viscosity, and the observation of color and odor. The experimental results showed that the gel and cream containing 5% GA, both formulations have proper stability in the centrifugal test, hot-cool cycling test, viscosity, pH stability and the observation of color and odor. On the other hand, the 5% GA ointment did not have stability. We concluded that the formulations of gel and cream are more suitable than ointment to use GA ingredient for developing cosmetic in terms of stability.

• Journal of Pharmaceutical Investigation
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• 제39권5호
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• pp.353-357
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• 2009

As a synthetic analog of the naturally occurring hormone somatostatin, octreotide has been commercially formulated in poly(lactide-co-glycolide) (PLGA) microspheres for the treatment of acromegaly. The purpose of this study was to evaluate stability of octreotide acetate in aqueous solutions at various pH values and PLGA films. Stability-indicating reversed-phase high-performance liquid chromatographic method was developed with good precision and accuracy, and it was applied to the stability studies. In aqueous solutions at pH 2.5-9.0, the degradation of octreotide followed approximately first order kinetics and the most favorable stability was found at pH 4. In PLGA films, the formation of acylated octreotides reached approximately 55% of the released octreotides. Various acylated octreotides was structurally identified by liquid chromatography-mass spectrometric analysis.

• Kyungpook Mathematical Journal
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• 제48권1호
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• pp.45-61
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• 2008

We investigate the generalized Hyers-Ulam-Rassias stability in p-Banach spaces for the following functional equation which is two types, that is, either cubic or quadratic: 2f(x+3y) + 6f(x-y) + 12f(2y) = 2f(x - 3y) + 6f(x + y) + 3f(4y). The concept of Hyers-Ulam-Rassias stability originated essentially with the Th. M. Rassias' stability theorem that appeared in his paper: On the stability of the linear mapping in Banach spaces, Proc. Amer. Math. Soc., 72 (1978), 297-300.

• 대한환경공학회지
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• 제38권5호
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• pp.228-235
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• 2016

아질산화 반응을 통한 nitrite 축적은 단축질소제거 혹은 anammox 공정 수립을 위해 필수적이고 이 반응의 속도가 전체 질소제거공정의 효율에 큰 영향을 미칠 수 있다. 본 연구는 부유 미생물 연속류 반응기에서 pH 농도가 암모니아 폐수(2,000 mgN/L) 처리에 주는 복잡하고 다양한 영향 들을 modeling과 실험을 통해 종합적으로 분석하였다. modeling 연구 결과 반응의 안정성(stability)은 pH에 의해 지대한 영향을 받으며, free ammonia 저해가 심해지는 알칼리성 환경일수록 안정적 운전 영역(stable region)은 축소되었다. 기질과 pH의 좌표 상에서 stable region과 unstable region을 가르는 경계(stability ridge) 근처에서 안정적인 최대반응속도를 얻을 수 있고, 이 운전조건에서 아질산 축적 가능성도 최대가 되었다. stability ridge 근처의 조건에서 반응기를 운전한 결과 아질산화속도는 안정적으로 약 $6kgN/m^3-d$까지 얻을 수 있었고, 아질산축적율은 약 99% 이었다. 그러나 unstable region에서는 부하증가를 통한 반복된 교란 결과 유출수 암모니아 농도가 회복 불가능한 상태로 상승하였다. Modeling 결과 고유(intrinsic) 최적 pH 값을 고정하여도 실험에서 관찰되는 최적 운전 pH는 사용 기질의 농도가 높을수록 낮아지는 것으로 나타났으며, 이는 문헌에서 보고된 경향과 일치 하였다. 본 연구의 modeling 조건에서 95% 아질산화(5%는 암모니아로 잔존)를 위한 최적 운전 pH는 ~8.0인 것으로 예측되었으나, anammox 유입수 생산을 위해 55% 아질산화하려 할 때의 최적 운전 pH는 ~7.2로 낮아 졌다.