• Publications of The Korean Astronomical Society
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• v.34 no.3
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• pp.31-40
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• 2019

We study the internal structure under the artificial mountain of Heumkyeonggak-nu, a Korean water-powered clock in the early Joseon dynasty. All the puppets on the artificial mountain are driven by the rotational force generated by the water wheel at their designated time. We design a model that work with three parts of the artificial mountain. At the upper part of the artificial mountain to the east, west, north and south, there are four puppets called the Four Mystical Animal Divinity and four ladies called the Jade Lady respectively. The former rotates a quarter every double hour and the latter rings the bell every hour. In the middle part of this mountain is the timekeeping platform with four puppets; the Timekeeping Official (Hour Jack), the Bell-, Drum-, and Gong-Warriors. The Hour Jack controls time with three warriors each hitting his own bell, drum, and gong, respectively. In the plain there are 12 Jade Lady puppets (the lower ladies) combined with 12 Oriental Animal Deity puppets. In his own time a lady doll pops out of the hole and her animal doll gets up. Two hours later, the animal deity lies down and his lady hides in the artificial plain. These puppets are regularly moved by the signal such as iron balls, bumps, levers, and so on. We can use balls and bumps to explain the concept of the Jujeon system. Iron balls were used to manipulate puppets of the timekeeping mechanism in Borugak-nu, another Korean water-powered clock in Joseon dynasty, which was developed earlier than Heumgyeonggak-nu. According to the North Korea's previous study (Choi, 1974), it is obvious that bumps were used in the internal structure of Heumgyeonggak-nu. In 1669, The armillary clock made by Song, I-young was also utilized bumps. Finally we presented mock-ups of three timekeeping systems.

• Bulletin of the Korean Mathematical Society
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• v.46 no.5
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• pp.1031-1040
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• 2009

It is shown that every almost positive linear mapping h : $\mathcal{A}\rightarrow\mathcal{B}$ of a Banach *-algebra $\mathcal{A}$ to a Banach *-algebra $\mathcal{B}$ is a positive linear operator when h(rx) = rh(x) (r > 1) holds for all $x\in\mathcal{A}$, and that every almost linear mapping h : $\mathcal{A}\rightarrow\mathcal{B}$ of a unital C*-algebra $\mathcal{A}$ to a unital C*-algebra $\mathcal{B}$ is a positive linear operator when h($2^nu*y$) = h($2^nu$)*h(y) holds for all unitaries $u\in \mathcal{A}$, all $y \in \mathcal{A}$, and all n = 0, 1, 2, ..., by using the Hyers-Ulam-Rassias stability of functional equations. Under a more weak condition than the condition as given above, we prove that every almost linear mapping h : $\mathcal{A}\rightarrow\mathcal{B}$ of a unital C*-algebra $\mathcal{A}$ A to a unital C*-algebra $\mathcal{B}$ is a positive linear operator. It is applied to investigate states, center states and center-valued traces.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.647-650
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• 2014

• Journal of the Korean Mathematical Society
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• v.55 no.3
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• pp.623-669
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• 2018

In Donaldson-Thomas theory, moduli spaces are locally the critical locus of a holomorphic function defined on a complex manifold. In this paper, we develop a theory of critical virtual manifolds which are the gluing of critical loci of holomorphic functions. We show that a critical virtual manifold X admits a natural semi-perfect obstruction theory and a virtual fundamental class $[X]^{vir}$ whose degree $DT(X)=deg[X]^{vir}$ is the Euler characteristic ${\chi}_{\nu}$(X) weighted by the Behrend function ${\nu}$. We prove that when the critical virtual manifold is orientable, the local perverse sheaves of vanishing cycles glue to a perverse sheaf P whose hypercohomology has Euler characteristic equal to the Donaldson-Thomas type invariant DT(X). In the companion paper, we proved that a moduli space X of simple sheaves on a Calabi-Yau 3-fold Y is a critical virtual manifold whose perverse sheaf categorifies the Donaldson-Thomas invariant of Y and also gives us a mathematical theory of Gopakumar-Vafa invariants.

• Nuclear Engineering and Technology
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• v.41 no.4
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• pp.447-454
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• 2009

This paper is a technical review of the research and development results of the Korea Nuclear Instrumentation and Control System (KNICS) project and Nu-Tech 2012 program. In these projects man-machine interface system architecture, two digital platforms, and several control and protection systems were developed. One platform is a Programmable Logic Controller (PLC) for a digital safety system and another platform is a Distributed Control System (DCS) for a non-safety control system. With the safety-grade platform PLC, a reactor protection system, an engineered safety feature-component control system, and reactor core protection system were developed. A power control system was developed based on the DCS. A logic alarm cause tracking system was developed as a man-machine interface for APR1400. Also, Integrated Performance Validation Facility (IPVF) was developed for the evaluation of the function and performance of developed I&C systems. The safety-grade platform PLC and the digital safety system obtained approval for the topical report from the Korean regulatory body in February of 2009. A utility and vendor company will determine the suitability of the KNICS and Nu- Tech 2012 products to apply them to the planned nuclear power plants.

• Bulletin of the Korean Mathematical Society
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• v.35 no.4
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• pp.641-652
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• 1998

Chung and et al. ([2].1991) introduced a new concept of a manifold, denoted by $^{\ast}g-SEX_n$, in Einstein's n-dimensional $^{\ast}g$-unified field theory. The manifold $^{\ast}g-SEX_n$ is a generalized n-dimensional Riemannian manifold on which the differential geometric structure is imposed by the unified field tensor $^{\ast}g^{\lambda \nu}$ through the SE-connection which is both Einstein and semi-symmetric. In this paper, they proved a necessary and sufficient condition for the unique existence of SE-connection and sufficient condition for the unique existence of SE-connection and presented a beautiful and surveyable tensorial representation of the SE-connection in terms of the tensor $^{\ast}g^{\lambda \nu}$. Recently, Chung and et al.([3],1998) obtained a concise tensorial representation of SE-curvature tensor defined by the SE-connection of $^{\ast}g-SEX_n$ and proved deveral identities involving it. This paper is a direct continuations of [3]. In this paper we derive surveyable tensorial representations of constracted curvature tensors of $^{\ast}g-SEX_n$ and prove several generalized identities involving them. In particular, the first variation of the generalized Bianchi's identity in $^{\ast}g-SEX_n$, proved in theorem (2.10a), has a great deal of useful physical applications.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.11-15
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• 2003

Ennin is a Japanese buddhist monk who traveled Tang from Jun. 13, 838 A D. to Dec. 14, 847 A D. in lunar's calender and wrote lengthy diary through the travel. This diary contained not only his wandering and triumphs but also politics, economy, social culture, religion, diplomatic policies, militaries, geography, transportations and administrations. Furthermore, the beginning of his diary dated Jun. 13, to July 3, 838 A. D. is recorded in the manner of ship's logbook entries. Many terms of navigation and naval architecture appears on it. It is very important to understand them for study ancient ship and its navigation skill. This Per aims to invest the meaning of “no-a” obviously refers to some part of hull of the ship upon first step to annotate the terms which are appeared in the diary.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.231.1-231.1
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• 2015

Surface energy, being an important material parameter to control its interactions with the other surfaces plays a key role in bio-related application. Carbon films are found very promising due to their characteristics such as wear and corrosion resistant, high hardness, inert, low resistivity and biocompatibility. The present work deals with the deposition of carbon films using unbalanced facing target magnetron sputtering technique. The discharge characteristics were studied using optical emission spectroscopy and correlated with the film properties. Surface energy was investigated through contact angle measurement. The ID/IG ratio as calculated from Raman spectroscopy data increases with the increase in power density due to the higher number of sp2 clusters embedded in the amorphous matrix. The deposited films were smooth and homogeneous as observed by Atomic force microscopy having RMS roughness in the range of 1.74 to 2.25 nm. It is observed that electrical resistivity and surface energy varies in direct proportionality with operating pressure and has inverse relation with power density. The surface energy results clearly exhibited that these films can have promising applications in cell cultivation.

• Solar Energy
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• v.17 no.2
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• pp.35-42
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• 1997

Thermal diode is a device which allows heat to be transferred in one direction by convection due to difference of density of fluid, and blocks heat flow in the opposite direction. Vertical plate for heat collection and radiation are of utility for design of thermal diode. It was considered the transient and steady state of air filled thermal diode with guide vane which combined rectangular and parallelogrammic shape enclosures. $Gr^*$ was kept constantly on $1.11{\times}10^{10}{\sim}1.4{\times}10^{10}$ and error range was ${\pm}3%$ during the experiment. Nu was examined when inclined angle are $15^{\cir\c}\;and\;45^{\circ}$ and, also the experiments was carried out with and without guide vane as well. Specially, Nu was linearly increased due to increase of $Gr^*$, and the effect of guide vane and dimensionless channel depth was sensitive. Developed state of temperature began at dimensionless time $0.5{\sim}0.6$ due to variation of inclined angle, which is characteristic of system.

• The Southeast Asian review
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• v.22 no.2
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• pp.95-131
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• 2012

This study compares the two biggest Islamic organizations in Indonesia, Nahdlatul Ulama(NU) and Muhammadiyah. As previous studies focus on their theological and ideological aspects, this study tries to analyze not only their religious orientation but also position of religious leaders, organizational structure, leadership system, routine activities and susceptibility to new religious change. The second part of this paper deals with religious and socio-political backgrounds under which the two organizations were established and with differences in the ways of interpreting Islamic teachings. This will provide the basis for understanding the dynamics of their later development. The third part explores religious authority supported by both. For this, perspectives on established religious schools, rational interpretation of the Scriptures, mystical practices and hereditary succession of religious leadership are to be analyzed. In addition, the ways different attitudes towards religious authority have impacted on organizational structure are to be examined. The topic of the fourth part is leadership composition, and blood and teacher-student relationships among chairpersons are to be analyzed. The last part deals with how different orientations of the two have impacted on their activities and especially on the ways of accommodating new religious ideas. For this, the ways 'liberal Islamic thought' has been introduced, accommodated and negotiated in each organization are to be compared with. With these discussions, it is expected that religious orientations, organizational structure, leadership system and organizational flexibility of the two can be understood. This analysis can help to have a glimpse on Islamic development in Indonesia and of socio-cultural and political influences the two have exerted on Indonesian society.