저출산으로 인해 학령인구는 감소하고 있으나, 과대학교와 과밀학급 문제는 여전히 존재한다. 이러한 문제는 학교별 학생수요 예측이 어렵기 때문에 발생하며, 근본적으로는 학령인구 이동에 대한 예측의 불확실성에 기인한다. 이는 학교의 신설이나 이전 계획 수립에 장애가 된다. 장기적 관점에서 학생수요를 예측하기 위해서는 학령인구의 순이동 경향에 대한 파악이 선행되어야 한다. 따라서 본 연구는 지난 16년간 전국 인구이동자료를 바탕으로 시도별로 연령별 인구의 이동 경향을 파악하고 만 11세 인구를 대상으로 크리깅을 적용하여 전국규모의 순이동을 추정하였다. 분석결과, 학령인구의 연령별 순이동은 연령이 높아질수록 감소하 였다. 크리깅을 통해 추정한 결과, 만 11세 인구는 서울, 대구, 경기, 인천 등에서 높게 나타났으며, 서울 강남이나 대구 수성구와 같이 교육열이 높은 지역이나 송도 같은 신규 개발지로의 순이동 경향이 가시적으로 파악되었다. 이 연구는 전국을 범위로 장기간의 학령인구이동 경향을 제시하였다는데 의의가 있으며, 이는 국가차원의 교육 계획 수립에 기여할 수 있다.

The increase of feral cat population due to man-made activities, such as cat-mom activities, has become a social problem, although cats have lived with humans for a long time worldwide. Nevertheless, in Seoul City, the effectiveness of Trap-Neuter-Return (TNR) management plan has not been evaluated yet. In this study, we calculated the population size of feral cats in Seoul City, which is useful information for feral cat management. Seoul City was divided into 196 areas based on 2012 TNR density data. In each group, 3 areas were selected for a total of 9 areas. Out of those, 6 areas (3 apartment and 3 non-apartment areas) that could be clearly separated by mountains, rivers or roads based on Seoul City Geographical Information System (GIS) were finally selected and they were representative of the two different residential styles (44.21% apartment area and 55.79% non-apartment area). Population size of feral cats was estimated from 3 on-site surveys over 3 days. The results of the survey showed that the population of feral cats in Seoul City ranged between 209,772 and 272,816. Results of this study will be used to develop a policy to control and manage the population of feral cats.

PURPOSES: In this paper, the packing degrees of binary granular mixtures under vibration compaction were simulated by using DEM with spherical particles to evaluate the applicability of the DEM for aggregate packing degree estimation. METHODS: The packing degrees of fine particles, coarse particles, and their mixture with different fine particle fractions were evaluated in DEM simulation for given various material property conditions. In order to check the validity of estimated packing degrees of particle mixtures, analytical model such as Furnas model that is capable of considering wall effect and loosening effect. RESULTS : DEM with spherical particles showed good agrement with analytical solution in terms of the packing degrees of binary granular mixtures with various fine particle fractions for most of conditions. Also, it was found that not the vibration amplitude but the ratio of particle diameter with vibration amplitude should be considered to explain the susceptibility of particle packing degree with vibration amplitude for the same acceleration condition and that the reduction in elastic modulus to shorten computational simulation time should be carefully considered when the packing degree is the most important concern. CONCLUSIONS: It was concluded that DEM with spherical particles are good enough to estimate the packing degree of binary granular particles for most of conditions. However, the effect of inter-particle frictions between fine and coarse particles have to be studied further in order to clarify the issue relating poor predictions for high inter-particle friction conditions.

Water resources are the most important resources for all living things on the earth to grow and reproduce, and sustain agricultural, industrial, household, recreational and environmental activities. Since 97% of these water resources is a seawater, desalination is a practical choice of many water-poor countries. Currently MSF (multistage flash evaporation) and RO (reverse osmosis) that need 25 kWh and 4kWh per m3 of fresh water although thermal methods need 718kWh and pressure based-RO 1kWh. This work focuses on how to estimate highest osmotic pressure of many aqueous saturated solutions such as NaCl and fuel ethanol that reaches 343.07 bars of 26.47%, over 5000 bars, respectively. This work shows that Lewis equation (1908) fits within 10% of OLI pressure and the modified estimation of Chang (1983) within 1% accuracy.

Recently the incidence of rollover accidents has increased due to the increase of SUV, and the probability of occupant injury in rollover accidents is very high, so research is needed accordingly. In this study, PC-CRASH, which is a program used for traffic accident analysis, is used for checking rollover speed and rollover angle of each situation in case of rollover accident, and applied to design variables of LS-DYNA which is finite element analysis program, so deformation displacements of roof according to collision velocity and angle were derived. Also, it is possible to predict rollover vehicle speed by using the derived value and the measured deformation displacement of roof in actual rollover accident, and it is possible to reconstruct accident more accurately by applying to PC-Crash which is traffic accident reconstruction program, so it is thought that it can be utilized analyzing traffic accident usefully.

In this study, the leak signal was measured by using an accelerometer to analyze the basic data and methodology for the development of the leak point estimation method in the water supply pipe. The measured results were analyzed by frequency analysis and cross-correlation analysis for leakage signals, and the error range was compared and analyzed with the actual leak point distance. As a result, it was confirmed that the vibration intensity due to leakage from the water leakage point was attenuated according to the distance. In the case of the ductile iron casting used in the experiment, the intensity of the signal at the 945 Hz, 1,500 Hz, 2,300 Hz band was increased with the change of the pressure in the pipe at 4mm of leakage hole. Also, it was confirmed that as the water pressure increases, the intensity of the leak signal increases but the similarity of the signal decreases. The results of this study confirm that the accelerometer sensor can be used efficiently for leak detection and it can be used as a basic data for the analysis for the development of leak point estimation method in the future.

PURPOSES : The objective of this study was to evaluate the field applicability of chip seals using recycled aggregates by comparing performance between natural aggregates and recycled aggregates for chip seals. METHODS : In order to check the performance of chip seals using recycled and natural aggregates, Bitumen Bond Strength (BBS) test, Vialit and bleeding tests were carried out. Cationic emulsions (RS(C)-2 and latex modified RS(C)-2L) were used in the tests. Granite aggregates were used as the natural aggregate and recycled aggregate from road wastes were used as the recycled aggregate. The aggregate was used with uniform gradation between 10 mm and 4.75 mm to clearly compare the performance difference between natural and recycled aggregates. RESULTS : Test results showed that the aggregate retention was low for both natural and recycled aggregates when applying RS(C)-2 (unmodified emulsion), but there was almost no difference between them when applying RS(C)-2L and RS(C)-2L-1 (modified emulsion) in the Vialit test results. In the bleeding tests, there was no bleeding for both natural and recycled aggregates when applying RS(C)-2 and RS(C)-2L. CONCLUSIONS: It was possible to apply chip seals using recycled aggregates in the field because the chip seals with recycled aggregates and RS(C)-2L (modified emulsion) showed aggregate retention similar to that of natural aggregates, and there was no bleeding.

2017년에 이어 2018년에도 경기도, 강원도 북부 8개 군과 한반도 북방 유사지역인 연길과 단동에서 벼, 옥수수, 콩, 감자, 맥류포장에 발생하는 주요해충을 조사하였다. 국내 북부지역의 벼에서는 벼물바구미 등 4종, 옥수수에서는 조명나방과 멸강나방, 콩에서는 진딧물 등 7종(콩나방은 연천의 1개 포장만), 감자와 밀에서는 진딧물이 발생하였다. 북방 유사지역에서의 해충 발생은 국내 북부지역과 유사하였으며 벼에서는 이화명나방, 콩에서는 잎벌레류와 들명나방, 감자에서는 가류이류와 큰28점박이무당벌레, 밀에서는 진딧물과 멸강나방이 발생하였다. 단동에서 이화명나방, 조명나방, 담배거세미나방, 톱다리개미허리노린재 등이 페로몬 트랩에 의한 유살수가 많았고, 콩나방은 적은 량이 유살되었다. 유효적산온도를 이용하여 벼멸구, 흰등멸구의 발생세대를 추정한 결과, 벼멸구는 7월 상순 비래 후 2세대 성충이 서해안에서는 9월 중순, 동해안에서는 9월말에 나오는 것으로 계산되었으나 그 외 북부지역에서는 발생하지 못하는 것으로 나타났다. 또한 벼멸구 비래량이 평년 수준일 경우 고사피해는 나오지 않을 것으로 추정되었다. 흰등멸구는 서해안과 동해안에서는 3세대, 내륙에서는 1-2세대를 경과하는 것으로 추정되었다.