• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.160-164
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• 1995

정보통신 시스템의 고속/고밀도화 요구에 따라 개발되고 있는 ATM(Asynchronous Transfer Mode) 교환기 시스템은 팬을 이용한 강제대류냉각 방식의 채택과 시스템이 설치되는 장소에 따른 여러 환경조건에 의한 진동 문제가 발생될 수 있다. 시스템의 진동으로 인한 피해중 커넥터 접촉부에서 전기적 특성의 변화는 고속으로 전송되는 신호의 왜곡을 유발시킬 수 있어 시스템 개발시 이에 대한 충분한 연구 및 시험이 요구되고 있다. 진동환경에서 커넥터 접촉부는 접촉면의 상대운동으로 인한 접촉저항의 증가와 순간적인 신호전달 중단을 가져오게 되며, 특히 PCB/Connector Assembly에서 커넥터 접촉부는 PCB(Printed Circuit Board)의 장착 조건 및 동적 거동에 따라 전기적 특성이 변할 수 있다. 시스템에서 커넥터의 동적 거동을 이해하기 위해서는 PCB를 포함하는 시스템내 여러 요소의 동적 특성 이해와 복잡한 해석과정이 요구되며, 시스템 개발자는 진동 환경에서 이것의 시험 결과에 따라 커넥터의 사용을 결정해야 할 것이다. 커넥터의 전기적 특성 시험법은 IEC, EIA드 여러 국제 규격에 제시되어 있으며, 본 연구의 대상이 된 ATM교환기 시스템에서 PCB/Connector Assembly의 진동환경에서 접촉저항 측정과 관련된 접촉저항 임계치 및 측정법은 IEEE 규격 및 Bellcore 규격에 규정되어 있다. Bellcore에는 주어진 진동시험주기 전후에 IEC 규격의 LLCR(Low Level Contact Resistance) 측정회로를 이용한 측정법이 규정되어 있고, 냉각팬 및 주위 환경진동이 가해지는 동안의 영향에 대한 시험법은 규정되어 있지 않다. 본 연구에서는 한국통신의 전자장비 운용환경시험 조건의 진동에서 ATM 교환기 시스템에 사용되는 PCB/Connector Assembly 커넥터 접촉부의 접촉저항 변화와 PCB 진동에 의한 영향을 시험하였다.proach)등이 제시되었고 평면파 영역에 한하여 해서되어져 왔다. 본 논문에서는 분할 접근 방법(Segmentation Approach)을 이용하여 다공 요소로 이루어진 소음기를 해석하는데 적용하였다.로 성능 및 안정도에 영향을 미치므로 주의 깊게 선정해야 한다. 방법의 실질적인 적용에는 어려움이 있다. 본 연구에서는 기존의 방법들의 단점을 극복할 수 있는 새로운 회귀적 모우드 변수 규명 방법을 개발하였다. 이는 Fassois와 Lee가 ARMAX모델의 계수를 효율적으로 추정하기 위하여 개발한 뱉치방법인 Suboptimum Maximum Likelihood 방법[5]를 기초로 하여 개발하였다. 개발된 방법의 장점은 응답 신호에 유색잡음이 존재하여도 모우드 변수들을 항상 정확하게 구할 수 있으며, 또한 알고리즘의 안정성이 보장된 것이다.. 여기서는 실험실 수준의 평 판모델을 제작하고 실제 현장에서 이루어질 수 있는 진동제어 구조물에 대 한 동적실험 및 FRS를 수행하는 과정과 동일하게 따름으로써 실제 발생할 수 있는 오차나 error를 실험실내의 차원에서 파악하여 진동원을 있는 구조 물에 대한 진동제어기술을 보유하고자 한다. 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile whereas relaxivity at high field is not affected by τS. On the other hand, the change in τV does not affect low field profile but strongly in fluences on both inflection fie이 and the maximum relaxivity value. The results shows a fluences on both inflection field and the maximum relaxivity v

• Korean Journal of Environment and Ecology
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• v.36 no.4
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• pp.390-401
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• 2022

This study investigated the characteristics of fish communities and inhabiting status of endangered species in the Bukcheon (Stream) of Seoraksan National Park, Korea from April to September 2020. A total of 4,356 fish of 7 families and 22 species were collected from 17 survey stations during the survey period. The dominant species was Zacco koreanus (relative abundance, 41.8%), and subdominant species was Rhynchocypris kumgangensis (relative abundance, 15.1%), followed by Pungtungia herzi (10.1%), Pseudopungtungia tenuicorpa (5.0%), Coreoleuciscus splendidus (4.1%), Zacco platypus (3.8%), Microphysogobio longidorsalis (3.5%), and Hemibarbus mylodon (2.2%). Among the fish species collected, 14 species (63.6%) were identified as Korean endemic species. There was one natural monument species (Hemibarbus mylodon), and four species of class II endangered wildlife that were designated by the Ministry of Environment (Acheilognathus signifer, Pseudopungtungi tenuicorpa, Gobiobotia brevibarba, and Brachymystax lenok tsinlingensis). Among the four species of class II endangered wildlife, B. lenok tsinlingensis inhabited in the upper stream, and A. signifer, P. tenuicorpa and G. brevibarba inhabited mainly in the middle-lower stream. Also, P. tenuicorpa, H. mylodon, and B. lenok tsinlingensis were inhabited in large numbers. Additionally, two cold-water fish species (R. kumgangensis and B. lenok tsinlingensis) and one landlocked species (B. lenok tsinlingensis) were collected. According to the results of cluster analysis, the dominance index decreased from upstream to downstream, but the diversity, evenness, and richness index increased; the cluster structure was divided into the uppermost, upstream, midstream, and downstream. The water quality of Bukcheon was evaluated as good overall since the river health (index of biological integrity) evaluated using fish was evaluated as very good (11 stations), good (2 stations), and normal (4 stations). However, river repair work was being carried out in some areas and some wastewater was flowing in from the midstream, therefore, supplementary measures to preserve fish habitats are required.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.4
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• pp.185-198
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• 2001

This study was conducted to reveal the effects of local climatic conditions on reproductive growth in a mature stand of Korean white pine based on climatic estimates. For this, the reproductive growth such as production and characteristics of cone and seed were first measured and summarized for seven years from 1974 to 1980. The local climatic conditions in the study site were also estimated by both a topoclimatological method and a spatial statistical technique. The local climatic conditions were then correlated with and regressed on the growth factors to reveal the relationships between the climatic estimates and the reproductive growth. Average number of conelet formation per tree showed highly negative correlation with some climatic variables related to minimum temperature in the year of flower bud differentiation. Especially, the most significant negative correlation were found between average of the minimum temperature for June and July of flower bud differentiation year and the number of conelet formation. There was no significant correlation between the number of cone production and climatic variables. However, total precipitation from December of the flowering year to February of the cone production year showed the most high correlation (r=0.6036) with the number of cone production. It was found that significant climatic variables affecting the amount of cone drop and cone drop percentage were the sum of cloudy days from June of the flowering year to August of the cone production year. Positive correlation was significantly recognized between the average weight of empty seed per cone and total precipitation from December of the flowering year to February of the cone production year. For the percentage of empty seed, five climatic variables among 19 variables were significantly correlated at 10% level. The average weight of a cone showed negative correlation with total precipitation from June of the flowering year to August of the cone production year. It was also found that average weight of a seed had highly negative correlation with total precipitation from December of the flowering year to February of the cone production year. The average weight of cone coat was negatively correlated with two climatic variables derived from clear days, which are sum of clear days from November of the flowering year to March of the cone production year and sum of clear days from December of the flowering year to February of the cone production year. On the other hand, it showed positive correlation with mean temperature of May in the flowering year. The exactly same results were obtained in correlation analysis for the percentage of cone coat.

• The korean journal of orthodontics
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• v.29 no.2 s.73
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• pp.197-207
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• 1999

Although there is a severe underlying skeletal deformity, the dentition has often maintained some occlusal contact and interdigitation by the teeth compensating in their positions for the skeletal problem, and these dental compensations are manifested in all three planes of space. The purposes of present investigation were 1) to study the pattern of dentoalveolar compensation of hyperdivergent skeletal pattern , and 2) to compare the dentoalveolar compensations of hyperdivergent skeletal pattern in children with adults. The samples selected for this study were consisted of 60 subjects in normal group, 60 subjects in hyperdivergent group. Each was divided into two subgroups by age ; child groups($8\~12yr$ old) and adult groups(17yr old over). The findings of this study were as follows; 1. In child, hyperdivergent subjects had smaller posterior lower facial height(p<0.01) and slightly longer anterior lower facial height than normal ones. In adults, they still expressed smaller posterior lower facial height and much longer anterior lower facial height than normal ones(p<0.01). 2. Hyperdivergent subjects had larger amount of upper and lower incisor relative eruption to their basal bone length than normal ones(p<0.05). In adult, relative eruption of upper incisor was increasing(p<0.05), although relative eruption of lower incisor remained the same as the child. 3. In child, there was no difference between hyperdivergent group and nomal one in the upper and lower molar relative eruption to their basal bone length. In adult, hyperdivergent group had target amount of upper molar relative eruption than normal ones(p<0.01), but relative eruption of lower molar was similar to normal ones. 4. Hyperdivergent group had larger angle between lower occlusal plane and mandibular plane than normal group(p<0.01). Upper occlusal plane of adult groups rotated more antero-superiorly than child groups, and adult hyperdivergent group had sleeper upper occlusal plane than normal group(p<0.05).

• Journal of Korean Society of Forest Science
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• v.85 no.3
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• pp.443-452
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• 1996

A study has been made to estimate biomass and NPP based on equation form of $Wt=aD^bH^c$ for Quercus variabilis and Quercus mongolica natural stands(Mean age; 67, 62yrs old) in Chungju. Equation form of $Wt=aD^bH^c$ was more adequate than $Wt=a(D^2H)^b$ and $Wt=aD^b$ for the estimation of the biomass and NPP. Individual biomass was compared using a paired t-test by tree component which showed no significant differences. Total aboveground biomass of Quercus mongolica was 130.6 t/ha and that of Quercus variabilis was 137.4 t/ha. Biomass of Q. mongolica was composed of foliage 5.1 t/ha(3.9%), dead branch 3.5 t/ha(2.7%), live branch 29.7 t/ha(23.0%), bolebark 16.2 t/ha(12.5%), and bolewood 74.9 t/ha(58.0%), and that of Q. variabilis was composed of foliage 3.8 t/ha(2.9%), dead branch 2.9 t/ha(2.2%), live branch 24.3 t/ha(18.4%), bolebark 20.4 t/ha(15.5%), and bolewood 80.4 t/ha(61.0%). Net primary production was 10.0 t/ha/yr in the Q. mongolica stand and 8.6 t/ha/yr in the Q. variabilis stand, respectively. Net primary production of Quercus forest in Chungju was very close to the mean NPP of the broadleaved forest of temperate zone.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.4
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• pp.337-346
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• 2013

It is necessary to consider the median lingual foramen carefully to prevent the bleeding due to the damage of the sublingual artery for implant surgery. This study is to evaluate the frequency, location, diameter and the number of the Mandibular median lingual foramen regarding gender and age in the CBCT. Sixty two images of cone beam computed tomography (CBCT) whose visited the Chonnam National University Dental hospital from Sept. 2010 to Apr. 2011 were evaluated. Frequency, number, location and the diameter of Mandibular median lingual foramen shown in the CBCT image were evaluated. Sixty two patients (100%) had at least one median lingual foramen and fifty six patients (90.32%) had multiple foramens. Forty patients (66.13%) showed the median lingual foramen on the location between Mn. central incisors. The mean vertical position of the genial spine and the median lingual foramen was 24.21 mm and 14.52 mm, respectively. And the relative mean vertical dimension of median lingual foramen was 0.45. The mean diameter of the foramen was 0.93 mm. CBCT demonstrated the frequency, location, diameter and the number of median lingual foramen. It is necessary to take CBCT before implant placement to prevent the bleeding.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.248-248
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• 2018

새만금 종합개발계획(정부, 2011)에 따른 내부개발의 완료시점은 2030년이며, 방수제 공사와 준설 등과 같이 만경강 및 동진강 유역 내 흐름을 변화시킬 수 있는 공사를 포함하고 있으므로 현재와 2030년의 하천 및 호의 수리특성은 다를 것이라 예상된다. 2030년까지 준설상황 등을 예측하여 반영하는 것은 사실상 불가능하기 때문에 새만금 종합개발계획에서 제시하고 있는 내부개발의 완료시점을 기준으로 홍수사상을 모의하였다. 새만금 호의 물리적인 변화는 수리특성의 변화로 이어질 수 있으며, 이는 상류지역으로 전파가 될 수 있으므로 호내 뿐만 아니라 만경강과 동진강 전역에 대한 홍수시의 수리특성을 검토하였다. 새만금 호와 연결된 만경강과 동진강의 설계홍수량은 대부분의 구간에서 100년 빈도이기 때문에 본 연구에서는 100년 빈도 홍수사상에 대한 분석을 기초로 홍수위 검토를 수행하였고, RCP8.5 시나리오를 적용한 100년 빈도 홍수량과 500년 빈도 홍수량에 대한 추가적인 연구를 수행하였으며, 이 결과를 토대로 취약지구 분석 및 대책 등을 제시하였다. 수치모의는 Delft3D를 이용하였으며, 새만금 유역의 동진강 지구의 실측치와 비교함으로써 모델의 적용성을 검증하였다. 서해안 조위 특성상 새만금 방조제는 조위 영향이 크므로, 이에 본 연구에서는 외조위의 특성을 고려하기 위해 새만금 유역 주변의 12개 조화상수(tidal harmonic constant)를 이용하여 조위에 대한 모의를 별도로 수행하고, 이 결과를 배수갑문의 경계조건으로 이용하였다. 상류 경계조건은 하천기본계획상에 제시된 하천은 이를 이용하였으며, 그 외의 소하천은 유역면적을 이용한 계산법을 사용하여, 선형적 면적 비유량(Specific Discharge, SD) 방법을 적용하여 본류의 유량에 부가하는 방식으로 수행하였다. 수치해석 결과, 준설 구간의 수위는 전반적으로 저하되었으며, 거리에 따른 수면의 경사를 분석한 결과 기존의 하천구역이 준설 등으로 인하여 호수의 특성으로 변화된 것으로 확인하였다. 본 연구에서 취약지구는 홍수위가 제방고의 약 80% 이상 되는 지역으로 결정하였으며, 이를 토대로 취약지구 분석을 수행한 결과 기존 100년 빈도에서 1지점, RCP 8.5 시나리오가 적용된 100년 빈도에서 88지점, 500년 빈도에서 125지점이 잠재적인 치수 위험이 있는 것으로 파악되었다. 기존의 1차원 연구결과와는 차이가 있는 부분은, 다수의 취약지구가 만곡부 또는 합류부 인근에 위치한 것이다. 향후 이러한 상대적인 치수 취약지점에 대해 정밀하고 국부적인 연구를 수행하여 정확한 홍수위 예측을 수행해야 할 것이다.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.129-135
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• 2008

USWMM was developed as a drainage analysis system for estuarine urban areas by adding sluice gates on existing EPA SWMM5 through this study. For the purpose of reviewing, Ansungchon river was modeled with USWMM and calibration and verification were attempted at three observation stations. In comparison, another approach using HEC-HMS and HEC-RAS was applied to the area under the same condition. It turned out that USWMM resulting values were closer to the observed values than those of the HEC-HMS and HEC-RAS approach. USWMM's flow simulation through sluices were more realistic to sluice operation fields by adding incomplete submerged orifice flow equation and maintenance water level. In sum, USWMM can be seen as a general purpose tool for estuarine urban drainage analysis system.

• Journal of Intelligence and Information Systems
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• v.7 no.1
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• pp.1-15
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• 2001

Recently, Internet based Electronic Commerce is recognized as one of the alternatives for strengthening sales power of small and medium companies. However, small and medium manufacturers can't adjust properly to the new environment because they are in short of money, personnel, and technology. To cope with this problem, this paper deals with the development of virtual manufacturing agent to support sales agent. The sales activity of most of parts manufacturing companies is based on orders of buyers. The process of promotion, receipt and selection of orders of the parts manufacturing is closely coupled with the load status of the production lines. On deciding whether to accept an order or not, as well as negotiating with buyers, sales person needs information such as load and schedule of production lines, manufacturability of the order. Therefore, the functions of virtual manufacturing agents manufacturability analysis, process planning, and scheduling are key features in developing an agent of sales activity for the parts manufacturing business. While most of research on virtual manufacturing system so far is focused on the simulation of each product, this paper deals with the development of agent assisting internet-based product sales by supporting production information promptly. The pilot system of virtual manufacturing agent is implemented using KQML-based agent template and Java-based expert system shell for a small molding company.

• Korean journal of applied entomology
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• v.17 no.2 s.35
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• pp.81-87
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• 1978

Late blight incited by Phytophthora infestans (Mont.) de Bary, is an important problem for seed potato prodcution in Korea. At the alpine Daekwanryeong area, unprotected potatoes are often defoliated within 14 days after late blight is first observed in the field. Since regular spraying can control late blight, the forecasting service is needed for timely initiation of the spraying program. Climatological data and notes on late blight incidence were recorded during 1970-1977 at the Alpine Experiment Station. The moving graph method using 7-day average mean temperature and 7-day total rainfall did not give highly accurate forecasts. Adding data on relative humidity and 7-day average minimum temperature increased the usefulness of the moving graph. Yields of late blight susceptible varietieties in sprayed plots were related to late blight occurrence and to the rainfall distribution pattern.