• Journal for History of Mathematics
• /
• v.26 no.2_3
• /
• pp.177-195
• /
• 2013

This study is the analysis of the concepts and the characteristics of the mathematics section of the College Scholastic Ability Test. The study starts with division of the history of the College Scholastic Ability Test into four periods. These are Introduction Period(school year 1994-1996), Adjustment Period(school year 1997-2004), Development Period(school year 2005-2011) and Conversion Period(up to present since school year 2012). The periodical division of the Mathematics section is considered as identical with that of the College Scholastic Ability Test. So we investigate the characteristics of the Mathematics section through the periodical classification. This study also proposes some tasks for the future Mathematics section of the College Scholastic Ability Test.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2006.04a
• /
• pp.259-263
• /
• 2006

Development and maintenance of forests are very important at Korea which has mountainous topography of more than 60% of the national territory. Under the circumstances, variety period's data is being required for the continuous monitoring of forest area. In this study, change of forests type was analyzed using Landsat TM satellite image which have multi-spectral bands. Furthermore, change detection system for forests type was constructed on web for the periodical monitoring. By using this system, everyone can easily use for the monitoring of forest type's periodical change.

• Korean Institute of Interior Design Journal
• /
• no.25
• /
• pp.191-197
• /
• 2000

This thesis is focused on the visitors varied experiences of the current museum architecture. The current trend and periodical development of visitors experiences are discussed by analyzing the factors such as the external symbol scheme, the exhibition space scheme, and the visitors circulation scheme which are involved with a visitors experience and thus classifying the experiences related to each sample museum. Examining and providing logical descriptions on each of the schemes helps comprehend the visitors varied experiences. This research, which deals with thoroughly understanding a museum as an architecture followed by taking visitors experiences into account, is aimed to contribute to improving visitors experiences in the course of designing a museum. The above-mentioned types of combination applied to each museum chosen for the research help understand the following : National museums show predominance of specific visitors experiences. As for the external symbol scheme, most of national museums have adopted the temple type, whereas international museums have equally adopted with the temple type and the showroom type which are characterized by its dedication to function and being in balance between contents and formalities.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.32 no.4
• /
• pp.61-70
• /
• 1990

In rural settlement planning, its spatial development framework should be constructed on the basis of the hierachial settlement system. However, up to now, there does not exist widely - accepted model on rural settlement hierachy. In this study the basic planning principles and directions on the modelling of the settlement hireachy in rural areas have been consolidated through theoretical study and situational analysis on planning environments. And also, a new yardstick on the grading of the middle - level centers between villages and rural towns has been tried to find out. The research resulted that the existance of periodical rural market might be used as a simple and innovative yardstick on the hierachial ordering of rural settlement system. Based on the above results, an alternative 4 - step model of rural settlement hierachy was proposed ; Rural Town(county hall sitted) -Market Center(having standard periodical market) - Village Center(having no market) - Village. Finally, because the conclusion has been made by very limited case studies and several previous works, there should need continuous studies and checks in future for full reasoning of the proposed model.

• Journal of the Korean Society for Heat Treatment
• /
• v.13 no.1
• /
• pp.16-20
• /
• 2000

There have been little reports on the degradation of medium-carbon steel tubes served at high temperature for a long period. The purpose of this research was to provide the information of the proper replacement span of the tubes with the new ones. We investigated the medium-carbon steel tubes which were used at petrochemical plant for about 50,000 hrs to examine their mechanical properties and microstructures. Experimental results showed that the tubes satisfied the specification of ASTM despite such a long period of service, but mechanical properties, especially charpy impact values, were reduced. It concludes that the tubes on service at the plants needs a periodical inspection.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.2214-2215
• /
• 2008

KESCO performed periodical inspection every 1${\sim}$3 years to check the status of maintenance and performance of electric installations for general use (less than 600V in voltage and 75kW in capacity in residential homes) but recently a resident have been avoiding periodical check due to increase of sex crime and empty house, which more and more difficult to secure electrical safety of installation. In order to solve non-inspection problems and improve efficiency of inspection, this paper introduce the model of remote monitoring system that check electrical facilites for general use and we are developing remote monitoring device for reliability test.

• Journal of the Korean Institute of Rural Architecture
• /
• v.10 no.4
• /
• pp.17-24
• /
• 2008

The development of industry compared late with another area but the apartment industry in Junrabukdo has called into expansion in volume to the demand increase suddenly because the population concentrates on the cities by growth of economy rapidly. Under that conditions, the regionalism is to be strong that the degree of dependence on the first industry is to be high. But, it was care naught for the character of resident and offered a model apartment in continually that be in fashion in cities. Thereof demanders familiarized with that. There, the purpose of this work is to survey the character of apartment, aims of offer and basic material when plan of apartment in local city and rural.

• Steel and Composite Structures
• /
• v.45 no.6
• /
• pp.831-837
• /
• 2022

Numerical investigation on dynamic characteristics of sandwich plates under periodic and thermal loads has been presented by assuming that the plate has three layers which are a foam core and two skins. The foam core made of Aluminum has porosities with uniform and graded dispersions. The sandwich plate has been supposed to be affected by periodical compressive loads. Also, temperature variation causes uniform thermal load. The formulation has been established based upon a higher-order plate theory and Ritz method has been used to solve the equations of motion. The stability boundaries have also been obtained performing Bolotin's method. It will be indicated that stability boundaries of the sandwich plate depend on periodical load parameters, porosities, skin thickness and temperature.

• Applied Chemistry for Engineering
• /
• v.16 no.5
• /
• pp.653-659
• /
• 2005

When emulsion is irradiated by a microwave, the energy absorbed by the emulsion is proportional to irradiation time. In case of a long exposure, the temperature of emulsion rises, its viscosity decrease, and subsequently increase the rate of demulsification. In this work, in order to improve demulsification rate, the studies on demusification and the Sauter mean diameter ($D_{32}$) for each microwaved emulsion with different irradiation mode(continuous, pulsative, and periodical irradiation) have been carried out. When the 30% W/O emulsion (sample #1) was irradiated for 600 sec and settled for 24 h, oil recovery rates from continuous, pulsative, and periodical microwave irradiation were 60.0%, 62.3%, and 96.2%, and the amounts of separated water were 26.5%, 35.0%, and 93.9%, respectively. Also, the Sauter mean diameters ($D_{32}$) were $47.183{\mu}m$, $111.547{\mu}m$, and $220.476{\mu}m$, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.11
• /
• pp.67-77
• /
• 2007

In sensor networks, it is very important to refresh communication keys of sensors in a periodic or on-demand manner. To perform a dynamic key management efficiently, sensor networks usually employ cluster architecture and each CH (Cluster Head) is responsible for key management within its cluster. In cluster-based sensor networks, CHs are likely to be targets of capture attacks, and capture of CHs threatens the survival of network significantly. In this paper, we propose a periodical key refreshment scheme which counteracts against capture of CHs. First, the proposed scheme reduces the threat caused by compromise of CHs by forcing each CH to manage a small number of sensors and changing CH role nodes periodically. Second, the proposed scheme flings attackers into confusion by involving other nodes in a key establishment between BS (Base Station) and a CH. Our numerical analyses showed that the proposed scheme is more secure than other schemes and robust against compromise of CHs.