• Journal of the Korean Society for Precision Engineering
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• v.2 no.3
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• pp.13-19
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• 1985

Servo의 안정성: Servo는 정상상태, 과도상태의 특성을 문제삼기에 앞서 먼저 안정하지 않으면 안된다. 제어량과 제어편차와 같이 제어 loop 속의 신호가 일정치에 수검하지 않는 현상을 불안정이라 한다. 제어량의 feedback을 정(positive)으로 하며 일반 목표치에는 수검하지 않고 제어편차는 단조롭게 정, 또는 부(negative)의 방향으로 발산한다. 이것은 접속 잘못에 의한 이상현상에 속한다. 이것에 대해서, 부 feeeback으로 하여도 제어 량이 목표치에 수검하지 않고 지속적으로 진동하는 불안현상도 있다. 이들은 선형발진과 비선형발진으로 구분할 수 있다.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.65-65
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• 1991

레이저 분광학의 연구에 있어서 고출력이며 좁은 선폭인 레이저광이 요구된다. 특히 고리형 공진기 레이저는 이득물질에서 공간 홀 버닝 효과 (Spatial Hole Burning effect)를 줄이거나 없앨수 있으므로 정상파로 발진하는 레이저에 비하여 높은 출력의 단일모드 발진을 얻을 수 있다. 8자형 고리 공진기 레이저에서 외부 되반사경과 코팅되지않은 에탈론의 조합을 사용하여 높은 출력의 단일모드를 얻었다. 색소분자의 에너지 준위를 2준위 구조로 가정하여 고리형 색소레이저에 있어서의 단일모드 발진의 안정성(Stability)을 살펴보았으며 양방향으로 단일모드 발진을 하는 경우에 있어서의 쌍안정(Bistability) 상태를 확인하였다.

• 건강소식
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• v.30 no.2 s.327
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• pp.12-13
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• 2006

일반적으로 아이들은 어른보다 활동적인 경향이 있어 적절한 체력수준을 유지한다. 그러나 해부학적, 생리학적, 심리학적으로 미성숙하기 때문에 운동프로그램을 고안할 때 특별한 주의가 필요하다.아이들을 위한 운동프로그램에서 가장 중요한 것이 안정성이다. 아이들은 신체활동 시 부상률이 높고, 지구성운동이 과할 경우 골단성장판을 다칠 수 있기 때문에 더욱 안정에 유의한다. 또한 아이들은 성인에 비해 열자극에 적응하는데 상대적으로 무력하므로 온도가 높은 여름날 야외에서 운동할 경우, 물을 많이 섭취하게 하고 자주 휴식을 취하도록 한다.

• The monthly packaging world
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• s.59
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• pp.174-178
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• 1998

주지하는 바와 같이, 자연환경 속에서는 분해되지 않는 안정적 소재인 플라스틱의 대량 생산이 오늘날 커다란 환경문제로 대두되고 있다. 플라스틱으로 인한 환경오염문제 해결방안의 일환으로서, 사용 후, 미생물의 작용에 의해 물과 탄소가스로 분해되는 생분해성 플라스틱의 연구가 1980년대 후반부터 활발해졌으며, 현재까지는 미국, 유럽, 일본 등지에서 만흔 제품이 개발돼 왔다. 생분해성 플라스틱은 농림$\cdot$수산용자재, 토목$\cdot$건축자재, 포장용기분야 등에서의 용도가 기대되고 있으나, 범용플라스틱에 비해 아직은 가격이 훨씬 비싸다는 것이 그 용도확대의 걸림돌이 되고 있다. 이 글에서는 생분해성 플라스틱의 개발동향, 시험법표준화와 안정성 등을 포함하여, 생분해성 플라스틱의 앞으로의 실용화 가능성을 살펴보기로 한다.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.440-445
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• 2018

In this study, the stability of O/W cosmetic facial cream emulsions according to HLB values was evaluated by mixing nonionic surfactants, such as Brij 78&72 and Brij 98&92. Brij 78&72 (steareth-20&steareth-2, EMS-01), saturated fatty acid, and Brij 98&92 (oleth-20&oleth-2, EMS-02), unsaturated fatty acid, were used as mixed surfactants. The stability of the O/W emulsion was evaluated by using the emulsion viscosity, particle size, particle size distribution, and zeta-potential. The viscosity of the emulsion increased with the increase of time for EMS-01 while that of EMS-02 decreased with the increase of HLB value. The particle size of both EMS-01 and EMS-02 increased with time. The emulsifier with a HLB value of 10.8, which is the most similar to the required HLB value of mineral oil, 10.5, had the smallest particle size and highest density and also showed the highest emulsion stability. The zeta-potential of both emulsions tended to increase with the HLB value. No significant changes were observed in emulsions of the HLB value of 10.8 or more. The saturated fatty acid system, EMS-01, exhibited a higher zeta-potential value than that of the unsaturated fatty acid EMS-02 and also was superior in the stability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1147-1151
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• 2001

We investigated stabilities of blue pigment extracted from Gardenia jasminoides at various conditions to check its applicability for beverages. Gardenia blue pigment with maximum absorption at 587 nm was obtained from the reaction of glycine and genipin (aglycone of geniposide). The blue pigment was found to be relatively unstable at acidic pH but very stable at alkaline conditions with half-life values of 102 days and 126 days at PH 9.0 and PH 11.0, respectively. The pigment also showed high thermal stability with half-life value of 55, 18, and 2 days at 50, 70, and 9$0^{\circ}C$, respectively. The addition of inorganic ions, sugars, and amino acids to model beverage containing this blue pigment increased retention rate at room temperature while addition of vitamin C decreased the stability. The sensory evaluation of the model beverage showed that inorganic ions and amino acids increased overall acceptability, indicating that the blue pigments of Gardenia jasminoides can be used as a natural colorant for leverage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.677-683
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• 2016

In urban areas, underground tunnel construction sites have spread widely to accommodate rapidly increasing traffic volume along with a high-degree economic growth. Earth tunneling might be adapted frequently for the underground space securing, and various tunneling methods have been developed to stabilize the tunnel face and crown. Among them, the DSM (divided shield method) is gaining popularity for its enhanced stability and construction efficiency. This method has its foundation from the Messer Shield method, which is one of the trenchless special tunneling methods. This study examined the effects of face reinforcement on construction the sequence through a large scale soil chamber test and numerical analyses. The chamber has a size of a 1/2 scale of the real tunnel. Surface settlements were measured according the tunneling process. Commercially available software, MIDAS GTS, was used for numerical analysis and its result was compared with the values obtained from the chamber test. The results of the study show that both settlements of the embanked soils and the stress of the tunnel girder are located within the safe criteria. Overall, this study provides basic data and the potential of using a reinforced tunnel face to enhance DSM applications.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.47-51
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• 2012

In this study, the deformation behavior stability of sealing rings with three different cross sectional areas has been presented using a FEM technique. To investigate the deformation behavior stability, the initial compression rate of 25% has been applied to the sealing ring, which is molded with a nitrile butadiene rubber. The maximum strain, maximum stress, and maximum contact normal stress have been analyzed for the working fluid pressure of $25kgf/cm^2$. The FEM results show that the maximum strain of a hollow o-ring and a hollow rectangular ring with a hollow space in the center of a sealing ring is higher than that of a conventional o-ring, but the maximum stress and the maximum contact normal stress are low. In these results, the sealing rings with a hollow space in the center of the cross sectional area is recommended to increase an extended endurance stability of sealing rings. But, the solid sealing ring is designed to guarantee the sealing safety of a contact sealing ring.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.1
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• pp.91-104
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• 2014

An Excavation Damaged Zone (EDZ), in which rock properties are permanently changed due to blasting impact or stress redistribution, can influence the behavior and stability of structures. In this study, the mechanical stability of an underground opening was simulated by using FLAC, which is a two-dimensional modeling code, with a consideration of EDZ. A sensitivity analysis was also carried out with fractional factorial design. From the modeling, it was found that the behavior and the stability of an underground tunnel are strongly dependent on the existence of the EDZ. The sensitivity analysis showed that the key parameters affecting the factor of safety around the tunnel are in-situ stress ratio, depth, cohesion, reduction ratio, internal friction angle, and height and width of the tunnel. It is necessary to consider the EDZ, which can significantly affect mechanical stability in tunnel design.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.2
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• pp.247-251
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• 2010

Using SCM in storage systems introduce new potentials for improving I/O performance and reliability. In this paper, we study the use of SCM as a buffer cache that guarantees transactional unit writes. Our proposed method can improve storage system reliability and performance at the same time and can recover the storage system immediately upon a system crash. The Proposed method is based on the LINUX JBD(Journaling Block Device), thus reliability is equivalent to JBD. In our experiments, the file system that adopts our method shows better I/O performance even while guaranteeing high reliability and shows fast file system recovery time (about 0.2 seconds).