• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1541-1545
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• 2009

홍수 기간 중 부유잡목에 의한 수위상승 원인은 크게 상류부에서 이송되어진 유송잡물에 의한 교량 등의 수공구조물에 집적으로 인한 통수능 부족에 의하여 발생되는 수위상승과 하천내 수공 구조물의 부적절한 설계 및 시공으로 인한 수위상승으로 구분되어 진다. 현재 교량의 여유고 산정에 사용되는 홍수위는 통수능을 고려하지 않은, 하천정비계획에 사용되는 홍수위를 적용하고 있으며, 다만 통수능의 확보를 위하여 경간장에 대한 제한을 두고 있을 뿐이다. 중소하천에 위치하는 교량의 경우, 여유고 확보에 대한 기준을 적용함에 있어서 교량이 위치한 하천 단면에서의 통수능의 영향이 고려되어야 유수의 월류에 대한 위험성을 줄일 수 있다. 더욱이 하천설계기준(2005)에서는 고정 홍수량에 의한 여유고 산정치를 제안하고 있을 뿐이기 때문에, 하천설계기준에서 교량과 관련된 여유고도 하상변동과 만곡부에 의한 수위 상승, 유송잡물에 의한 통수능 영향, 계산오차 등을 고려하여 충분한 여유고를 확보하도록 보완할 필요가 있다. 본 연구에서는 부유잡목에 의한 수위상승 원인을 분석을 하고, 이에 따른 수리모형실험을 통하여 부유잡목의 높이/폭(H/B)변화에 의한 수위상승, 부유잡목의 형태별 수위상승, 교각사이 개도비에 따른 수위 상승량을 산정하여 기존의 여유고에 대한 추가적인 여유고를 확보하여 홍수시 통수능을 확보하고자 하였다. 부유잡목의 형태에 따른 수위상승량을 산정하기 위하여 개도비를 70%로 고정한 후, Fr수를 변화시켜 부유잡목의 높이/폭(H/B) 형태에 따라 산정한 결과, 부유잡목이 존재하지 않는 상태에 비하여 부유잡목에 의한 영향으로 인한 수위증가율이 Fr값이 클수록 더욱 크게 나타났으며, 부유잡목이 동일면적인 경우 폭(B)에 비하여 높이(H)가 커질수록 수위 상승이 크게 나타났다. 또한, Fr수 변화에 따른 최고수위 상승율을 구하였을 때, 상류조건에서 Fr < 0.5 인 경우는 기존 여유고에 대하여 최대 10%의 여유고를 추가 확보하며, 0.5 < Fr < 1 인 경우는 기존 여유고에 대하여 최대 20%의 여유고를 추가 확보하도록 설계하는 것이 바람직하다.

• Land and Housing Review
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• v.3 no.3
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• pp.287-297
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• 2012

To develop 80MPa-high strength concrete with ternary cement used in OPC, blast-furnance slag, and fly ash, mixing ratio of blast-furnace slag and fly ash was evaluated in material characteristics before and after hardening of the high strength concrete. According to the evaluated results of material characteristics before and after hardening of the high strength concrete, the flowability and long-term compressive strength increase up to 30% mixing ratio of blast-furnace slag and fly ash. Also, it is superior to characteristics of length change and neutralization due to the use of mineral admixture when compared in test sample mixed with OPC. The evaluated results show that material characteristics of the high strength concrete was the most outstanding performance at blast-furnace slag of 25% and fly ash of 15%. The result of this study will be useful for the development of high strength concrete as a substitute of costly silica fume in the near future.

• Journal of Nutrition and Health
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• v.48 no.5
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• pp.441-450
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• 2015

Purpose: The purpose of this study was to investigate the effects of hypertension relevant nutrition knowledge on practices for prevention of hypertension in Chinese college students studying in South Korea. Methods: We conducted a survey of 276 Chinese students studying more than three months in Korean universities who were aged 19 and older about hypertension and sodium relevant nutrition knowledge, intake of salty processed food, hypertension prevention practices, and stages of behavior change for hypertension. Results: The average score on the questionnaire for hypertension relevant nutritional knowledge was 40.62 out of 50 points, and the average score for sodium relevant nutritional knowledge was 24 out of 30 points. Kimchi was the most frequently eaten salty processed food. The average score for hypertension prevention practices was 3.10 out of 5 points. The behavior change stages for prevention of hypertension were contemplation (47.1%), action (32.2%), and pre-contemplation (20.7%). The students received high scores on nutrition knowledge and showed significantly higher scores on the action stage than on pre-contemplation or contemplation. Nutritional knowledge of hypertension and sodium showed positive correlation with hypertension prevention practices, whereas negative correlation with salty processed food intake. Conclusion: Development of an education program for Chinese students in Korea on hypertension and sodium relevant nutritional knowledge is needed so that they can practice for prevention of hypertension.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.366-366
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• 2009

후면접합 태양전지는 상용 태양전지의 수평전류 손실(lateral current loss) 이 없으며, 전면전극에 의해 발생하는 그림자 손실(shading loss) 줄인 고효율 태양전지의 하나이다. 생성된 반송자가 후면에 위치한 전극에서 수집되기 때문에 효율향상을 위해서는 불순물에 의한 재결합을 줄이는 것이 중요하다. 따라서 Gettering 은 높은 소수반송자 수명(life-time)을 가지는 고품위 실리콘 기판은 고효율 실리콘태양전지 제작을 위한 중요 요소 기술이다. 본 연구에서는 n-type c-Si 기판을 이용한 고효율 실리콘 이종접합 태양전지제작을 위해 external gettering 공정을 이용하여 고품위 실리콘 기판을 제작하였다. POC13 doping process 의 온도, 시간을 변화시킴으로써 이에 따른 변화를 관찰하였다. 주사전자현미경(SEM)를 통해 etch pit 을 확인 했으며,Four point probe 를 통해 면저항을 측정, 인(P)의 농도를 계산 하였다. 계산된 면저항을 통해 인(P)의 확산 깊이를 계산하였다. Iodine passivation 된 시편을 Qusi-steady state photoconductance (QSSPC)를 이용하여 소수반송자 수명을 측정함으로써 gettering 에 의한 bulk lifetime 향상 효과를 관찰하였다.

• Korean Journal of Remote Sensing
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• v.18 no.2
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• pp.91-96
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• 2002

The performance characteristics of a satellite imager using a Time Delay and Integration(TDI) Charge Coupled Device (CCD) with fixed integration time is investigated for the variation of satellite altitude and tilt angle. In consequence of the investigation TDI synchronization using tilt imaging is proposed as a solution to compensate geometric performance degradation due to altitude decrease. The tilt angle optimized for the TDI synchronization at decreased altitude is presented. This result can be used for a TDI CCD imager with variable integration time in a certain range as well.

• The Journal of the Korea Contents Association
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• v.20 no.10
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• pp.401-410
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• 2020

This study is to conduct a 12-month f/u survey on changes of metabolic syndrome (MetS) components according to the resting heart rate (RHR) in patients with essential hypertension (HTN) without cardiovascular disease (CVD) complication. We used the KorHR (Korean Hypertension Registry) data and a total of 951 subjects were analyzed using the R statistical program. As a result of this study, it was found that the risk and changes of MetS components differs according to the RHR group with first and revisit hypertensive patients. Therefore, guidelines for customized RHR control for first and revisit hypertensive patients should be prepared. Also, it is necessary to prepare various interventions to control the RHR. Through this, it is intended to prevent the occurrence of CVD caused by HTN, which is a representative chronic disease, to improve the quality of life of patients and their families as well as to contribute to increasing the efficiency in the health care.

• Journal of the Korean Association of Geographic Information Studies
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• v.6 no.2
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• pp.92-100
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• 2003

Analysis and results of the relationship between the NDVI and terrain element such as elevation, slope, aspect in Chunahn city area are as follows. It does not show the linear relationship between NDVI and analyzed terrain element such as elevation, slope, aspect, etc. and there is a trend such that the deviation of NDVI is decreased as the elevation and slope is increased. It appears that there is trends such that the distribution range of NDVI is discontinuously changed as the elevation and slope is increased. The distribution range of NDVI is discontinuously decreased based on about 50m and 100m borderline in elevation case, and slope $10{\sim}20^{\circ}$ borderline in slope case, respectively. Any special trend is discovered in the relationship between aspect and NDVI.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1613-1622
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• 2010

In this paper, the ultraprecision positioning control of an ultrasonic linear motor in a high-vacuum environment is presented. The bolt-clamped Langivin type transducer (BLT) with the 3rd longitudinal; and 6th lateral vibration modes was developed, which was excited by using the Eigen resonance frequency for two vibration modes in order to generate stable and high power. In practical applications, however, even if a geometrical design has an Eigen frequency, discordance between both mode frequencies can be generated by the contact mechanism and because of manufacturing errors as well as environmental factors. Both mode frequencies were precisely matched by adjusting the impedence. By using this method, the BLT can be driven under any environmental conditions. The nominal characteristic trajectory following(NCTF) control method was adopted to control the positioning of the system in vacuum. The developed linear motor stage show high positioning accuracy with 5 nm.

• The Korean Journal of Quaternary Research
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• v.23 no.1
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• pp.1-24
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• 2009

Paleosol layers lying on top of the terrace in Jeongdongjin area appear to have been deposited under generally well-drained condition with periodic waterlogging. From a 4.5m-long profile observed, a total of 6 stratigraphic units were identified. Grain-size analysis indicates the dominance of silty and clay materials with some portions with high sand content. Major mineralogical elements are quartz, feldspar, mica and chlorite. Geo-chemical composition shows little change throughout the stratigraphy with some fluctuation in chemical weathering index. Marked increase in magnetic susceptibility is recognizable where stratigraphic unit changes. Soil- wedge layer is developed around 50cm below the surface with concentration of grains of AT tephra (c. 25,000 BP). An OSL date of c. 110,000 BP was obtained from a sand layer lying below the paleosol.

• Journal of The Geomorphological Association of Korea
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• v.18 no.2
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• pp.53-63
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• 2011

The changes and causes of channel section in Naeseongcheon River, a tributary of Nakdong River, during the long(1984~2001) and short(2009~2011) periods are analyzed. There are the declines of channel height with a maximum of approximately 2m in the most areas of the lower reaches during the past 20 years. These are thought as the influences of active aggregate collections and river dredging. The size of sand bar within the channel at the NM1 decreases greatly during the past 2 years. This may results from the decrease of sediment supply due to the Yeongju Dam construction in the upper reaches. However, the NM2 and NL2 where the natural channel are preserved experience the slight increase of height during the past 2 years. Therefore, the anthropogenic channel interferences in Naeseongcheon River have greatly influenced on the declines of channel height by the decrease of sediment supply.