• Journal of Life Science
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• v.18 no.4
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• pp.585-589
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• 2008

Chronophin is a phosphatase responsible for the dephosphorylation of cofilin, which regulates the rearrangement of actin cytoskeleton. It is also known as a phosphatase for pyrodoxal 5'-phosphate (PLP), an active form of vitamin $B_6$, and maintains the level of PLP in the cytoplasm. Since this phosphatase belongs to a HAD subfamily containing a cap domain, it is expected to undergo a conformational change for the binding of a substrate. However, the crystal structure of chronophin has a disulfide bridge between the cap and core domains preventing a movement of the cap domain against the core domain. It is possible that the disulfide bond between C91 and C221 was formed by an oxidation during the crystallization. Here, we obtained chronophin crystals under a reduced condition and determined the crystal structure. This reduced chronophin does not contain a disulfide bridge and shows a closed conformation like the oxidized form. It implies that an active chronophin binds its substrate under the closed conformation without the disulfide bond and shows a high substrate specificity in the cell.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1023-1032
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• 1995

The multiple cooperating robot system plays an important role in the research of modern manufacturing system as the emphasis of production automation is more on the side of flexibility than before. While the kinematic and dynamic analysis of a single robot is performed as an open-loop chain, the dynamic formulation of robot in a multiple cooperating robot system differs from that of a single robot when the multiple cooperating robots form a closed kinematic chain holding an object simultaneously. The object may be any type from a rigid body to a multi-joint linkage. The mobility of the system depends on the kinematic configuration of the closed kinematic chain formed by robots and object, which also decides the number of independent input parameters. Since the mobility is not the same as the number of robot joints, proper constraint condition is sought. The constraints may be such that : the number of active robot joints is kept the same as mobility, all robot joints are active and have interrelations between each joint forces/torques, two robots have master-slave relation, or so on. The dynamic formulation of system is obtained. The formulation is based on recursive dual-number screw-calculus Newton-Eulerian approach which has been used for single robot analysis. This new scheme is recursive and compact symbolically and may facilitate the consideration of the object in real time.

• Journal of the Korean Magnetics Society
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• v.8 no.2
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• pp.49-56
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• 1998

Explicit and closed-form expressions describing magnetic behaviors of uniaxial magnetic materials are derived. Explicit and closed-form expressions for magnetic torque, magnetization orientation, and thier derivative functions with respect to the intensity and the orientation of an applied field. Those explicit expressions could give elegant mehtods of measuring magnetic anisotropy and saturation magnetization by the least squre fitting. In addition, on could use them to study the distribution function of magnetic propeties of a non-interacting magnetic aggregate.

• Elastomers and Composites
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• v.38 no.3
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• pp.251-261
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• 2003

The flame retardancy and foaming properties of NBR foams containing waste ground tire rubber (GTR) were studied. When the composition ratios of NBR/GTR were ranged in $100/0{\sim}80/20$ (w/w) and rubbers/flame retardants were in the range of $1/1.95{\sim}3.70 wt%$, the considerably optimized foam for flame retardancy was obtained with high limiting oxygen indices (LOI, $29.4{\sim}40.0$), low heat release rate(HRR), closed/semi-closed cell of uniformity, and reasonable expandability ($215{\sim}300 %$). The LOI was increased and the heat release rate was decreased with increasing the amount of GTR content.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.1-8
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• 2010

Wireless multimedia service through the access to mobile telephone network or data network is a vital part of contemporary life, and the demand for frequency spectrum for new services is expected to explode as the ubiquitous computing proliferate. Cognitive radio is a technology, which automatically recognizes and searches for temporally and spatially unused frequency spectrum, then actively determines the communication method, bandwidth, etc. according to the environment, thus utilizing the limited spectrum resources efficiently. In this paper, we investigate the effects of imperfect sensing, misdetection and false alarm, on the primary and secondary users' spectrum usage through the analysis of continuous time Markov Chain. We analyzed the effects of the parameters such as sensing error, offered load on the system performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.507-512
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• 1997

This paper presents a method of finding optitnal joint torques of two robots when they hold an object simultaneously. Although the importance of the multiple cooperating robot system increases for more flcviblc ni;mufacturing automation, dynamic solutions to multi-robot system forming closcd kinematic chain is not easy to find. Newton-Eulcr approach is used for the dynamic formulation of two robots fonn~ng closcd kincmatic chains gmsping a rigid body object. The nrcthodology to optimize the joint torques to satisfy given criterta and obtain bettcr control of the system is discussed. The scheme is illustrated by an example.

• Magazine of the Korea Concrete Institute
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• v.10 no.1
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• pp.125-132
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• 1998

경량골재 콘크리트의 내구성과 경제성에 대한 인식 부족으로 조경재료나 인공토양 둥 구조부재 이외의 분야에 사용되고 있는 국내 실정에 비해서, 구미 여러나라에서는 고강도 경량골재를 장지간 교량과 고충건물에 사용하고 있다. 경량골재 콘크리트는 구조물의 재료비 단순비교에 있어서도 경제성이 있을 뿐만 아니라, 자중감소로 인한 구조적, 기하학적 장점도 있으며, 또한 고강도 경량골재의 개발로 경량골재가 가지고 있는 여러 문제점을 해소하여 사용성과 내구성에 있어서 보통골재 콘크리트와 큰 차이가 없는 상황이다. 그러나국내에서 생산된 경량골재는 닫힌 공극보다 열린 공극을 많이 내포하고 있어 수분흡수가 많고, 특히, 동결융해에 대한 내구성에 취약한 문제점을 가지고 있다. 본 논문에서는 내동해성 향상을 위해 10종류의 고강도 경량골재 콘크리트 공시체를 제작하여 실리카 흄, 물.시멘트비, AE제, 강섬유 등을 실험 변수로 하여동결융해 실험을 수행하였다. 연구결과 실리카흄, 물.시멘트 비는 어느 정도 내동해성을 향상시키지만 근본적인 해결방안이 되지 못하며, AE제를 첨가한 공시체와 강섬유를 사용한 공시체는 동결융해 내구성 지수가 90%이상으로 측정되어 내동해성을 개선시킬 수 있는 요소로 나타났다.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.04a
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• pp.23-23
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• 2003

분말야금된 소결체의 가장 큰 특징 중의 하나는 피할 수 없는 소결체의 기공이다. 이러한 기공이 기계적 특성에 미치는 영향에 관해서는 많은 연구가 오래 전부터 진행되었었다. 그러나 기존의 연구는 거의 대부분 일반 분말야금에 의한 것이고 분말사출성형된 소결체의 기공율과 기계적 특성 광계는 거의 연구가 이루어 지지 않았다. 본 연구에서는 기공율의 조절이 용이한 분말사출성형 공정을 이용하여 소결 초기부터 완전 치밀화에 가까운 조직까지 다양한 소경율의 시편을 만들어 기계적 특성에 미치는 순수기공의 영향은 조사하기 위해 다음과 같이 조사하고자 하였다. 사출성형에 사용된 재료는 고강도 이며 내식성이 뛰어난 17-4 PH STS이고 평균 입경은 10mm였다. 열분해와 소결은 수소 분위기에서 행하였으며 소결온도는 900~$1350^{\circ}C$였다. 연구수행을 통해 다음과 같은 결론을 얻었다. 1. 기공율과 기계적 특성의 관계는 닫힌 기공이 지배하는 고밀도 영역과 열린 기공이 지배하는 저밀도 영역을 분리하여 해석해야한다. 2. 저밀도 영역에서의 기공율과 강도의 관계는 넥 성장에 따른 load bearing area의 증가로 나타낼 수 있고 아래와 같다. $\frac{\delta}{\delta_o}=1-\frac{P}{P_i}$ 3. 고밀도 영역에서의 기공율과 강도의 관계는 소결 현상과 초기 충진율을 고려한 ideal pore모델을 도입하였고 아래와 같이 나타났다. $\frac{\delta}{\delta_o}=1-1.95(P_i\;{\cdot}\;P)^{2/3}$

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.714-717
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• 2017

Among the factors considered in the design stage of a space launch vehicle using liquid propellant, research has been focused out on the pogo phenomenon, longitudinal dynamic instability. The pogo phenomenon refers to the instability that the longitudinal vibration of the launch vehicle structure causes a change in the pressure and flow rate of the fluids in propulsion system, and this change re-excites the fuselage structure. This mechanism constitutes a closed system to gradually increase the vibration of the launch vehicle. This paper specifically focuses on the dynamic analysis of pressure and flow changes in the propulsion system. Based on the example study of the space shuttle, the acoustic modal analysis of the propulsion system is performed to predict the modes of the supply line causing instability of the fuselage.

• Sijohaknonchong
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• v.42
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• pp.93-115
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• 2015

Dynamics of Sijo was regarded as a genre of 'closed nature' once. But ironically thanks to the 'closed nature', today dynamics of Sijo is refocused in diverse fields. Sijo is quoted not only in its original field of literature, but also in writing study. Quite remarkably, it is often referred to in the field of literary therapy, further in emotional healing. This article discussed the dynamics of Sijo as a manifestation of emotion especially called Gamsung in the process of the refocus. It is to show effectively that as a literary genre, Sijo can interact and share what is reasonal as well as what is emotional and sentimental in a poem as an emotional container beyond the lyricism Sijo has. Of course, it is also clear that the concept of lyricism may limit the dynamics of Sijo itself. Thus, the key word 'Gamsung' mainly referred to in this article was used to show the dynamics which Sijo has as much as possible, overcoming the limitation. That is, the purpose of the study is to prove that Sijo is the genre to represent human emotion most dynamically by reviewing the reasonal aspect of Sijo in addition to its emotional disposition which has been estimated to focus on sentiment or emotion. In the process of reinterpreting the structure of Sijo, the specific analysis on such emotional disposition and reasonal aspect was conducted by structurizing that as '(1) Facing, (2) Feeling dynamical, (3) Interpellating by feeling, and (4) feeling by sensation'.