• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.412-412
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• 2023

정부는 2027년까지 식량자급률 55.4%를 달성하고, 채소·과실류 국내 공급 여력의 85% 수준을 유지하기 위한 적정 농지면적 150.0만ha가 필요하다고 추정하였다. 그리고 정부는 적정 면적 확보를 위해서 농지보전 목표가 포함된 중장기 기본계획을 수립할 예정이다. 이러한 식량자급률 달성과 채소 및 과실류 재배 면적 확보를 위해서는 논의 다각적인 활용 방안을 모색할 필요가 있다. 왜냐하면 최근 쌀 공급과잉 문제를 해결하기 위해 최근 '양곡관리법'이 정치적 이슈로 등장할 만큼 쌀 공급과잉 해소와 논 농지의 효율적인 활용에 대해 사회적 관심이 많다. 이러한 맥락에서 본 연구에서는 우리나라 최초로 논 배수 개선을 위해 지하암거가 설치된 경북상주시 공검면 일대를 대상으로 암거배수의 성과를 살펴보고 개선방안을 모색하였다. 이를 위해 본 연구에서는 지하암거 설치로 배수여건이 개선된 수혜농가 42명을 대상으로 심층면담을 실시하였다. 사례지역은 오태저수지를 기점으로 시작하는 공검소하천 양안에 넓게 위치하고 분지지형으로 하천보다 낮은 저지대로, 평상시·강수시 지하수위가 높아 습답이 형성되어 영농기계 사용이 어렵고, 일부지역의 경우 작물 파종, 수확을 하지 못하는 등 피해 발생하여 영농여건이 매우 불리한 지역이다. 이러한 배수불량을 개선하기 위해 수혜면적 55.6ha에 (지하)배수가 정비되었다. 이러한 배수 개선이 지역 영농에 미치는 효과는 다음과 같이 분석되었다. 첫째, 수혜구역 내 농가들은 배수불량으로 농기계 작업이 불편하고, 논의 습답을 제거하기 위해 해당 시설에 대한 필요성을 느끼고 있다. 또한 암거배수 시설로 인해 약 72% 농가들은 습답 개선의 효과가 있는 것으로 나타났다. 둘째, 전체 수혜농가의 약 72%는 암거시설로 인해 논의 습답이 개선된 것으로 나타났다. 특히, 암거시설로 인해 물빠짐이 개선되었고, 농기계 작업이 용이하게 되었다. 다만 사업 첫해에는 논을 파헤쳐 농기계가 빠지는 피해가 있었지만, 2차년도부터는 논이 정비되어 농기계 빠지는 피해는 없는 것으로 분석되었다. 셋째, 수혜 농가들이 느끼는 "습답 피해가 매우 있음"은 사업 시행 전 51.61%에서 사업 완료 후에는 4.17%로 급격히 감소하였다. 또한 "습답 피해가 전혀 없음"을 느끼는 농가는 사업 시행 전 3.23%에 불과했지만, 사업 완료 후에는 20.83%로 급증하였다.

• Journal of the Korean Geotechnical Society
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• v.22 no.1
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• pp.53-61
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• 2006

Soil liquefaction occurs by complex dynamic interaction between soil particles and pore fluid. Therefore, experimental researches have been widely performed to analyze liquefaction phenomena. In this research, centrifuge tests were performed to analyze the liquefaction behavior of horizontal sand ground. Centrifugal acceleration was 40g and the thickness of model ground was 25cm, which simulates 10m thickness in prototype scale. Viscous fluid was used as pore fluid to remove the time scaling difference between dissipation and dynamic shaking. Test results showed that the dissipation of excess pore pressure is the combined behavior of solidification and consolidation. In addition, the solidification rate, the ground acceleration amplitude, and the dynamic permeability during solidification were influenced by the confining pressure.

• Journal of the Korean Geotechnical Society
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• v.22 no.4
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• pp.61-71
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• 2006

A numerical procedure is presented fur evaluating seismic liquefaction on sloping ground sites. The procedure uses a fully coupled dynamic effective stress analysis with a plastic constitutive model called UBCSAND. The model was first calibrated against laboratory element behavior. This involved cyclic simple shear tests performed on loose sand with and without initial static shear stress. The numerical procedure is then verified by predicting a centrifuge test with a slope performed on loose Fraser River sand. The predicted excess pore pressures, accelerations and displacements are compared with the measurements. The results are shown to be in good agreement. The shear stress reversal patterns depend on static and cyclic shear stress levels and are shown to play a key role in evaluating liquefaction response in sloping ground sites. The sand near the slope has low effective confining stress and dilates more. When no stress reversals occur, the sand behaves in a stiffer manner that curtails the accumulated downslope displacements. The numerical procedure using UBCSAND can serve as a guide for design of new soil structures or retrofit of existing ones.

• The Korean Journal of Applied Statistics
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• v.37 no.4
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• pp.499 -508
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• 2024

In this paper, we investigate hierarchical time series forecasting that adhere to a hierarchical structure when deriving predicted values by analyzing segmented data as well as aggregated datasets. The occurrences of food poisoning by a specific pathogen are analyzed using zero-inflated Poisson regression models and negative binomial regression models. The occurrences of major, miscellaneous, and overall food poisoning are analyzed using Poisson regression models and negative binomial regression models. For hierarchical time series forecasting, the MinT estimation proposed by Wickramasuriya et al. (2019) is employed. Negative predicted values resulting from hierarchical adjustments are adjusted to zero, and weights are multiplied to the remaining lowest-level variables to satisfy the hierarchical structure. Empirical analysis revealed that there is little difference between hierarchical and non-hierarchical adjustments in predictions based on pathogens. However, hierarchical adjustments generally yield superior results for predictions concerning major, miscellaneous, and overall occurrences. Without hierarchical adjustment, instances may occur where the predicted frequencies of the lowest-level variables exceed that of major or miscellaneous occurrences. However, the proposed method enables the acquisition of predictions that adhere to the hierarchical structure.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.33-35
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• 2012

본 연구에서는 전이금속 Cu, Mn이 함침된 제올라이트를 사용하여 일산화탄소의 흡착능을 연구하였다. 금속 복합 산화물촉매 제조는 Cu, Mn을 서로 다른 비율로 물리 혼합하여 지지체에 담지하였다. 제올라이트 분자체는 상용 13X를 사용하였다. 함침방법은 과잉용액 함침법을 사용하였고, 건조 후 소성 하여 산화물 형태로 담지하였다. 합성된 개질 흡착제의 표면특성 분석은 $N_2$흡착 및 탈착곡선을 통한 질소흡착 특성 분석으로 기공크기, 기공분포, 비표면적을 구하였으며, FT-IR, X-선 회절분석, 전자주사현미경, $NH_3$-TPD/TPR 으로 특성을 분석하였다. 흡착 실험은 고정층 반응기에서 수행하였으며, 내경 4 mm 석영관에 흡착제를 충진하고 흡착파과곡선을 Gas Chromatograph로 측정하여 Cu-Mn 제올라이트 촉매의 일산화탄소 흡착 성능을 연구하였다. Cu-Mn 함량 비율과 흡착조업조건에 따른 흡착능을 측정하여 최적 흡착조건을 구하였다.

• Korean Journal of Materials Research
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• v.8 no.1
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• pp.80-84
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• 1998

본 연구에서는 석영을 기판으로 사용하여 텅스텐 실리사이드 게이트를 고온에서 결정화시키고, 이\ulcorner 발생되는 crack 에 대한 생성원인을 조사하였다. 증착된 텅스텐실리사이드의 실리콘 조성과 실리콘 완층충의 두께가 증가함에 따라 열응력이 감소하는 경향이 관찰되었으며, 과잉의 실리콘 조성을 가진 실리사이드를 열처리한 경우에는 crack에 대한 저항이 증가함을 알 수 있었다. 그러나 실리콘 완충층을 사용한 경우는 두께가 증가함에 따라 열응력이 감소하는 경향이 있으나, crack이 보다 쉽게 발생되는 결과를 얻었다. 이는 실리사이드 반응에 의하여 거칠어진 계면에 응력이 집중되어 crack생성을 쉽게하는 것으로 여겨진다. 결과적으로 석영과 텅스텐실리사이드의 열\ulcorner창계수차이에 의하여 생성되는 열응력이 crack생성의 주원인으로 작용하고, 실리콘 완층층을 사용한 구조하에서는 계면에서 일어나는 실리사이드반응이 crack생성에 큰 영향을 미치는 것으로 생각된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4C
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• pp.329-336
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• 2010

Distributed source coding (DSC) system moves computational burden from encoder to decoder, so it takes higher decoding complexity. This paper explores the problem of reducing the decoding complexity of practical Slepian-Wolf coding using low-density parity check accumulate (LDPCA) codes. It is shown that the convergence of mean magnitude (CMM) stopping criteria for LDPC codes help reduce the 85% of decoding complexity under the 2% of compression rate loss, and marginal initial rate request reduces complexity below complexity minimum bound. Moreover, inter-rate stopping criterion, modified for rate-adaptable characteristic, is proposed for LDPCA codes, and it makes decoder perform less iterative decoding than normal stopping criterion does when channel characteristic is unknown.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.21-24
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• 2010

The cooling channel of the preburner for staged combustion engines was studied. The combustion pressure of the researched preburner is about 210 bar which is very high compared with the engines of the Korean Launch Vechicle and 30 ton class liquid rocket engines developed as a pre-research program. Also, the combustion is an oxygen rich process unlike the gas generators of open cycle kerosene engines. Thus the cooling process is very important to make the preburner stable. Many configurations for the preburner were developed and numerically analyzed. As a result, the pressure loss could be reached below the target.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.9 no.2
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• pp.174-179
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• 1998

Objective：Present study investigated the relationship between mothers' self-perception and perception of children's problems. Method：Subjects were 63 children, mothers, who visited child & adolescent psychiatric clinic. Their mothers completed Minnesota Mulpiphasic Personality Inventory(MMPI) & Korean Personality Inventory for Children(KPI-C). Correlation between validity scales of mothers' MMPI and validity scales of KPI-C was analysed, and then we divided subjects into two group(High & Low Group) according to the MMPI validity scales, and compared KPI-C's validity scales by student t-test. Result：There were significant positive correlation(r=.30) between K scale of MMPI and L scale of KPI-C, significant negative correlation(r=-.32) F scale of MMPI and L scale of KPI-C. The Means of T scores did show significant difference according to MMPI F, K scales in KPI-C L scale, to MMPI L scale in KPI-C F scale. Conclusion：These results indicated that defensive mothers tend to perceive her child's problems more defensively. However mothers who exaggerate their problem more severely, do not exaggerate their children's problem. Therefore, these result suggested that we should be careful not to underestimate children's problem whose mother elevated in K scale of MMPI.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.16 no.1
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• pp.106-116
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• 2005

Summary : This study was designed to identify the difference in temperament, parent-adolescent's goodness of fit and behavioral problems between early-adolescent high risk group which can be divided into subgroups (ADHD-I and ADHD-HI/C) and normal group. Method : Subjects of this study were students of a Boy's Middle School and their parents. ADHD high risk group was determined by using three rating scales of ADHD behavioral symptoms : 1. Korean-ADHD Rating Scale, 2. Abbreviated Conners Parents Rating Scale, 3. Conners-Wells' Adolescent Self-Report Scale. Final research was based on the subjects including 25 people in ADHD-I high risk group, 70 ADHD-HI/C high risk group, 70 in normal group. Revised Dimensions of Temperament (DOTS-R) was used for students to assess their temperament, while DOTS-R : Ethnology for parents to access environmental demands. Goodness of fit between parent and adolescent was figured out by results of the two scales. Korean Youth Self Report (K-YSR) was used to examine behavioral problems. Results : When it comes to temperament of adolescents, ADHD-HI/C high risk group was found to be associated with higher scores on general activity level. In contextual parent demand to adolescent, ADHD-HI/C parents showed higher level of demands in general activity than other groups, and lower expectation of positive mood than ADHD-I parents. In parent-adolescent's goodness/poorness of fit, the research found out that ADHD-I and ADHD-HI/C had lower level of fit on pesitive/negative mood than normal group and indicated that ADHD behavioral symptoms connected with poorness of fit in emotional relationship between adolescents and their parents. In behavioral problems, ADHD-HI/C high risk group had severe externalizing and internalizing problems distinctly. It had more severe in externalizing problems than ADHD-I, while there were no differences in internalizing problems between the two subgroups. Conclusion The two ADHD subgroups in high risk adolescents had differences on temperamental activity level and on goodness of fit about positive mood. In addition, they had different patterns in externalizing/internalizing problems.