• The Korean Journal of Malacology
• /
• v.25 no.1
• /
• pp.29-33
• /
• 2009

This study devised and tested a histological staging system for gonadal development in the trumpet shell, Charonia sauliae, which was collected along the south coast of Jeju Island, South Korea. This paper details for the first time the gonadal development characteristics of C. sauliae. Ovary and testis development in C. sauliae can be roughly divided into five stages: growing, mature, spent, degenerative, and resting. The trumpet shelll has multiple fecundation and fertilization during the spawning season for out-of-step gonadal development in high-temperature and low-salinity environments. Female trumpet shell tended to have larger shells and were more abundant than males (64.26% of all animals collected were female).

• Korean Journal of Environment and Ecology
• /
• v.13 no.4
• /
• pp.348-353
• /
• 2000

지리산국립공원 동부지구의 주요 등산로를 대상으로 운동부하 보행속도 휴식시간 비율을 조사한 결과 순수 보행시간 중 운동부하는 거림-세석평전구간이 92,4% 이며 장터목-천왕봉구간이 91.3%로 조사되었다 또한 중산리-장터목구간이 86.9% 세석평전-장터목구간이 85.3%로 조사되었다 보행속도는 장터목-천왕봉 구간이 3.97km/hr 세석평전-장터목구간이 3.06km/hr 로 조사되었으며 거림-세석평전구간은 2.23km/hr 중산리-장터목구간은 2.02km/hr,조사되었다 전체등산시간중 휴식시간의 비율은 거림-세석평전구간이 26.0%이며 중산리-장터목구간이 22.6%로 조사되었다 세석평전-장터목구간은 3.0% 장터목-천왕봉구간은 0%로 조사되었다.

• Molecules and Cells
• /
• v.26 no.6
• /
• pp.517-529
• /
• 2008

Porosomes are supramolecular, lipoprotein structures at the cell plasma membrane, where membrane-bound secretory vesicles transiently dock and fuse to release inravesicular contents to the outside during cell secretion. The mouth of the porosome opening to the outside, range in size from 150 nm in diameter in acinar cells of the exocrine pancreas, to 12 nm in neurons, which dilates during cell secretion, returning to its resting size following completion of the process. In the past decade, the composition of the porosome, its structure and dynamics at nm resolution and in real time, and its functional reconstitution into artificial lipid membrane, have all been elucidated. In this mini review, the discovery of the porosome, its structure, function, isolation, chemistry, and reconstitution into lipid membrane, the molecular mechanism of secretory vesicle swelling and fusion at the base of porosomes, and how this new information provides a paradigm shift in our understanding of cell secretion, is discussed.

• Korean Journal of Child Studies
• /
• v.15 no.2
• /
• pp.55-68
• /
• 1994

A survey analysis of home video games was carried out for 1,018 elementary school children. Children responded to a questionnaire consisting of sociodemographic variables, degree of game participation(frequency and mean time), control behavior(eg. resting during games, lightening interior), and physical symptoms(eg. eyestrain, headache, trembling, paralyses) during and/or after playing games. Statistical analysis was done by frequency, percentile, and chitest. The results showed that many children enjoyed video games frequently and played continually, that few children did control behavior during games. Main variables related to degree of game playing and control behavior were sex, game experience, parent's education, and mother's activity. In particular, the results implied that the level of physical symptoms during and/or after game differed by lighting factors.

• Biomaterials and Biomechanics in Bioengineering
• /
• v.5 no.1
• /
• pp.51-64
• /
• 2020

In this study, the mathematical model that describes blood cell development in the bone marrow (i.e., hematopoiesis) has been studied via the Homotopy Perturbation Method (HPM). The results from the present work compared very well with the numerical solutions from published literature. This work has shown that the HPM is viable for solving delay differential equations born from hematopoiesis problem. The influence of the proliferating cells loss rate, time delay rate and the phase re-entry rate on the population densities of both the proliferating and resting cells were also determined through the underlined procedure.

• Proceedings of the Korean Society of Rural Planning Conference
• /
• 1998.10a
• /
• pp.22-24
• /
• 1998

This is a research with two purposes, in order to understand the situation with which mountain villages region gets faced present time. First, to examine the conception and the formative process of mountain villages region. Second, the measure the possibility of development in a project on mountain villages region to increase the evenings as a continuous project by bringing ecology tourism. The future plan for mountain villages region project will focus on building up natural resting places for citizens by offering the actual living area it self mountain villages region should be made a place where people can release fatigue or stress, rest, think, have fun and get relationship each other, villagers and citizens. For this, it, is needed to find the way to increase economic effect in mountain villages region after enough study of development peculiarity each mountain villages region has, propensity to consume, appropritate method and example, negative and positive influence.

• Earthquakes and Structures
• /
• v.3 no.3_4
• /
• pp.435-455
• /
• 2012

An impact on the ground surface may represent several phenomena, such as a crash of an airplane or an explosion or the passage of a train. In order to analyze and design structures and equipment to resist such a type of shocks, the response spectra for an impact on the ground must be given. We investigated the half-space motions due to impact using the finite element method. We performed extensive parametric analyses to define a suitable finite element model and arrive at displacement time histories and response spectra at varying distances from the impact point. The principal scope of our study has been to derive response spectra which: (a) provide insight and illustrate in detail the half-space response to an impact load, (b) can be readily used for the analysis of structures resting on a ground subjected to an impact and (c) are a new family of results for the impact problem and can serve as reference for future research.

• Advances in nano research
• /
• v.13 no.6
• /
• pp.599-617
• /
• 2022

In the present research, for the first time, the vibrational as well as buckling characteristics of a three-layered curved nanobeam including a core made of functionally graded (FG) material and two layers of smart material-piezo-magneto-electric-resting on a Winkler Pasternak elastic foundation are examined. The displacement field for the nanobeam is chosen via Timoshenko beam theory. Also, the size dependency is taken into account by using nonlocal strain gradient theory, aka NSGT. Then, by employing Hamilton's principle, energy procedure, the governing equations together with the boundary conditions are achieved. The solution procedure is a numerical solution called generalized differential quadrature method, or GDQM. The accuracy and reliability of the formulation alongside solution method is examined by using other published articles. Lastly, the parameter which can alter and affect the buckling or vocational behavior of the curved nanobeam is investigated in details.

• Journal of Microbiology and Biotechnology
• /
• v.11 no.4
• /
• pp.614-618
• /
• 2001

Low-threshold T-type $Ca^{2+}$ channels are distinctive voltage-operated gates for external $Ca^{2+}$ entry around a resting membrane potential due to their low voltage activation. These phenomena have already been extensively studied due to their relevance in diverse physiological functions. Recently, three T-type $Ca^{2+}$ channel ${\alpha}$$_1$subunits were cloned and their biophysical properties were characterized after expression in mammalian expression systems. In this study, ${\alpha_IG} and {\alpha_IH}$ low-threshold $Ca^{2+}$ channels were expressed and characterized in Xenopus oocytes after adding 5' and 3'untranslated portions of a Xenopus ${\beta}$ globin to improve their expression levels. The added portions dramatically enhanced the expression levels of the ${\alpha_IG} and {\alpha_IH}$ T-type channels. When currents were recorded in 10 mM $Ba^{2+}$ as the charge carrier, the activation thresholds were about -60 mV, peak currents appeared at -20 mV, and the reversal potentials were between +40 and +45. The activation time constants were very similar to each other, while the inactivation time constants of the ${\alpha_IG}$ currents were smaller than those of ${\alpha_IH}$. Taken together, the electrophysiological properties of the ${\alpha_IG} and {\alpha_IH}$ channels expressed in Xenopus oocytes were similar to the previously reported characteristics of low-threshold $Ca^{2+}$ channel currents.

• Journal of Biosystems Engineering
• /
• v.2 no.1
• /
• pp.49-54
• /
• 1977

In order to obtain the field efficiency of the power tiller plowing on the various size of and its length-width field tests were performed with 8ps.10ps. power tiller popularly used in the korean rural area, and Satoh 5ps. made in Japan, Land Master 5ps. made in England were tested to compare with the field efficiency of the above power tillers. The results obtained in this tests were as follows ; 1. In considering of the resting time and the refueling time and others, the field efficiency of Satoh was the highest among the power tillers as to be 80%, at the 8ps. power tiller 76.5%, at the 10ps. power tiller 79.3% and the lowest field efficiency was obtained at the Land Master as 75.7%. 2. The field efficiency of the each power tiller increased as the ratio of the length to width of the field was increased. 3. The increasing rate of field efficiency was much bigger in the below the ratio of 5 : 1 but at the upper ratio increased above, the ratio was nearly constant. 4. The field efficiency of the power tiller was higher at the smaller power tiller than the larger, except the Land Master , because of easily operating and turning of the power tiller by virtue of its lighter weight.