• Journal of the Korean Solar Energy Society
• /
• v.27 no.4
• /
• pp.137-146
• /
• 2007

This study is about the passive cooling effects of three outdoor solar shading facilities as trees, pergola with wistaria vine and membrane shading structure, which are expected to provide cool spots in the summer. Field observations of measuring thermal environment of selected facilities is executed. Thermal environment measuring was categorized as short wave radiation, long wave radiation, net radiation, globe temperature, surface temperature measured by infrared camera. Heat transfer mechanism is analyzed with overall data from field measurement. Results from this study are as below; 1) Radiation balance measured on shaded surface under membrane shading structure was 17%($86W/m^2$) of the unshaded surface radiation balance($511W/m^2$). 2) Surface temperature comparison between vegetation and membrane of the shading structure is performed at 3 o'clock in the afternoon. Surface temperature of vegetation was same as air temperature and that of membrane was $5^{\circ}C$ higher than air temperature. Vegetation transpiration is considered as the causing factor which make those differences. 3) Results from this study could be used as fundamental data for reducing heat island phenomena and continuos research on this subject would be needed.

• Sleep Medicine and Psychophysiology
• /
• v.5 no.1
• /
• pp.1-11
• /
• 1998

Chronobiology is the area of medicine that is, how time-related event shape our daily biologic responses and apply to any aspect of medicine with regard to altering pathophysiology and treatment response. In mammals, there are several evidences that prove suprachiasmatic nuclei(SCN) is the major circadian pacemaker and the circadian rhythm influences so many biological aspects of an living organism such as rest-activity, thermoregulation, reproduction, and endocrine system. In case of human beings, there had been little information of circadian system. That may be due to the experimental, technical difficulties to study but also to the fact that human has the more complex environments that may alter the circadina rhythm like the artificial light, many socio-cultural aspects and so forth. However, several reports of these days indicate human's circadian system is composed of two or more circadian oscillators and SCN is the major circadian oscillator among them like the other mammals. Free-running circadinan period of mankind is about 24 hours rather than about 25 hours, and rest-activity rhythm is polymodal like other species. In addition to that, human may have capcities to change the circadian rhythm as the seasonal changes of daynight schedule. In this article, the author will summarize recent progress of anatomy and physiology of the circadian clock mechanism in humans.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.26 no.1
• /
• pp.45-50
• /
• 1981

Diurnal changes in leaf stomatal resistances were measured on leaf positions and both surfaces to investigate the stomatal response to irradiance in wheat, var. Chokwang and barley, var. Dongbori 1. Stomatal frequency and size were also determined to explain the control mechanism of gas exchanges in two species. The leaf diffusive resistances of two species decreased, as the sun rose, to minimum at 10 to 11 o'clock a.m. and increased gradually in the afternoon, even faster at sunset. As the adaxial irradiance increased, stomatal resistances decreased sensitively in the range of 30uEm$^{-2}$ㆍsec$^{-1}$ to 150uEm$^{-2}$ㆍsec$^{-1}$ quantum flux density. The stomatal opening of the abaxial surface began at lower irradiance and was completed earlier than the adaxial surface. The adaxial irradiances decreased in order of leaf position, flag, the 2nd, the 3rd leaf, and the stomatal resistances increased in the same order. Even under the same irradiance, the stomatal resistance of lower leaves were higher than those of upper leaves. The stomatal frequencies of lower leaves were less, but the stomatal size was greater than those of upper leaves. Consequently, the relative leaf area occupied by stomatal pores were constant among leaf positions in two species.

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

• Journal of KIISE:Databases
• /
• v.32 no.5
• /
• pp.473-486
• /
• 2005

The Hippocratic database model recently proposed by Agrawal et at. incorporates privacy protection capabilities into relational databases. The authors have subsequenty proposed the Hippocratic XML daかabase model[4], an extension of the Hippocratic database model for XML databases. In this paper, we propose a new concept that we cail the dynamic predicate(DP) for effective access control in the Hippocratic XML database model. A DP is a novel concept that represents a dynamically constructed rendition that tan be adapted for determining the accessibility of elements during query execution. DPs allow us to effectively integrate authorization checking into the query plan so that unauthorized elements are excluded in the process of query execution. Using synthetic and real data, we have performed extensive experiments comparing query processing time with those of existing access control mechanisms. The results show that the proposed access control mechanism improves the wall clock time by up to 219 times over the top-down access control strategy and by up to 499 times over the bottom-up access control strategy. The major contribution of our, paper is enabling effective integration of access control mechanisms with the query plan using the DP under the Hippocratic XML database model.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.8
• /
• pp.11-19
• /
• 2012

In this paper, we propose a power-efficient scheduling scheme for lightly loaded multicore processors which contain more processing cores than running tasks. The proposed scheme activates a portion of available cores and inactivates the other unused cores in order to save power consumption. The tasks are assigned to the activated cores based on a heuristic mechanism for fast task assignment. Each activated core executes its assigned tasks with the optimal clock frequency which minimizes the power consumption of the tasks while meeting their deadlines. Evaluation shows that the proposed scheme saves up to 78% power consumption of the previous method which activates as many processing cores as possible for the execution of the given tasks.

• Biomolecules & Therapeutics
• /
• v.19 no.3
• /
• pp.308-314
• /
• 2011

It has been shown that circadian genes not only play an important role on circadian rhythms, but also participate in other physiological and pathological activities, such as drug dependence, cancer development and radiation injury. The Per2, an indispensable component of the circadian clock, not only modulates circadian oscillations, but also regulates organic function. In the present study, we applied mPER2-upregulated NIH3T3 cells to reveal the relationship of mPer2 and the cells damaged by ultraviolet C (UVC). NIH3T3 cells at the peak of the expression of mPer2 induced by phorbol 12-myristate 13-acetate (PMA) demonstrated little damage by UVC evaluated by MTT assay, cell growth curves and cell colony-forming assay, compared with that at the nadir of the expression of mPer2. Overexpression of mPER2, accompanied p53 upregulated, also demonstrated protective effect on NIH3T3 cells damaged by UVC. These results suggest that mPer2 plays a protective effect on cells damaged by UVC, whose mechanism may be involved in upregulated p53.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.8
• /
• pp.2158-2170
• /
• 1999

It has been required more reliable communication on processes and improvement of system performance as distributed systems using multicast protocol became widespread. In distributed environment maintaining data consistency through asynchronous execution of processes and coordinating the activities of them would occurs. This paper proposes a total ordering algorithm, TORMP, in order to resolve these problems. TORMP takes advantage of multicast protocol and uses an effective token passing method. It reduces a process delaying time before transmitting its message by multicasting a token simultaneously to every process that initiates the request of the message. Moreover, the processes receiving the token start multicasting the message at the same time, which causes to cut down the overall transmission dely. In case that one process sends a message, TORMP hardly uses the procedure of controlling for ordering. It gives fairly the right of sending messages to all processes in a group with utilizing vector clock. In TORMP, unlike other algorithms, the number of packets generated during ordering process does not depend on the number of processes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.10
• /
• pp.914-924
• /
• 1991

It has been generally used for PLL(Phase Locked Loop) to be synthesized randomly chosen frequency state, but the PLL locking time was inevitable element. A direct digital synthesizer. Which makes output frequency directly in sine wave by a phase accumulating method, could be leiminate the defect, although a phase distortion in frequency spectrum. In order to improve this disadvantage, the phase accumulating method is reconsidered in the side of he output wave formula expression. A new mechanism is proposed, and it is constructed by a most suitable logic elements. The spectrum of synthesized sine waveform is simulated and compared with a measured value, and it’s the coherence frequency hoppong state with the PN(Pseudo Noise) code sequence is confirmed. In this results, the power levels of phase distortion harmonics are decreased to 10~25dB and bandwidths are increased to 420kHz.

• Journal of Microbiology
• /
• v.33 no.3
• /
• pp.215-221
• /
• 1995

S. coelicolor A3(2) cells were treated with various redox-cycling agents on nutrient agar plates and examined for their effect on the growth and differentiation. When treated with plumbagin, severe effect on cell viability was observed at concentrations above 250 $\mu$M. However, the surviving colonies differentiated normally. When treated with 100 $\mu$M paraquat, growth rate was decreased and morphological differentiation was inhibited, while the survival rate was maintained at about 100% even at 5 mM paraquat. Menadione or lawsone did not cause any visible changes at concentrations up to 1 mM. The effect of paraquat was also observed when it was added to nutrient agar plate before spore inoculation. Paraquat had also observed when it was added to nutrient agar plate before spore inoculation. Paraquat had no effect on colonies growing on R2YE agar plates. Among the components of R2YE medium selectively added to nutrient agar medium, CaCl$_2$ was found to have some protective function from the inhibitory effect of paraquat. As a first step to study the mechanism of the inhibitory effect of paraquat on differentiation, resistant mutants which sporulate well in the presence of paraquat were screened following UV mutagenesis. Three paraquat-resistant mutants were isolated with a frequency of 3 $\times$10${-5}$. Their mutation sites were determined by genetic crossings. All three mutations were mapped to a single locus near arg4 at about 1 o'clock on the genetic map of S. coelicolor A3(2).