In order to understand the stress responses, we measured the concentration of stress hormones by using the fresh feces of wild otters in the Gwangju stream and Seomjin river during summer and winter in 2018. We compared seasonal and regional number of spraints (=otters’ feces), temperature, altitude, water width, land cover, and water quality with stress hormones. The stress hormone levels were higher in summer than in winter, and significantly different to season and region. In addition, the number of feces were different according to the season and region, and showed a negative correlation with stress hormone. This study suggested assessing stress hormones as another promising method for the analysis of status of wild otters and it will contribute to establish the management and conservation policy, especially in urban area.

본 연구는 보성강 유역에 위치한 호수들에서 식물플랑크톤 군집의 시공간적 차이를 비교하고 이러한 군집 구조의 차이에 영향을 미치는 요인들을 확인하고자 2014년 3월부터 2017년 11월까지 분기별 조사를 시행하였다. 조사 결과, 보성호는 다른 호수들에 비해 식물플랑크톤의 다양성이 풍부하고 밀도 역시 높은 수준으로 확인되어 시공간적으로 큰 차이를 보였다. 또한 3월 조사에서 확인된 식물플랑크톤 군집은 다른 조사시기와 우점종을 포함한 규조류와 녹조류의 군집에서 구분되는 특성을 나타냈다. Indicator species analysis를 통해 확인된 각 그룹 간 지표종을 확인한 결과, 계절에 따른 식물플랑크톤 천이와 영양 농도에 따른 다양성 및 밀도 변화를 반영한 것으로 산출되어 호수들의 식물플랑크톤 군집이 시공간적으로 구분되었음을 나타냈다. Non-metric multidimensional scaling을 통해 보성강 유역 내 호수들의 식물플랑크톤 군집 구조에 있어 Secchi depth, 수온, 전기전도도, DO 등이 중요한 요인임을 확인하였고, 영양염을 포함한 다양한 환경요인과 함께 식물플랑크톤 군집 차이에 영향을 끼친 것으로 분석되었다.

This paper proposes a method to reduce the pose error and to solve the dead reckoning issue which occurs when the mobile robot with continuous-tracks travels in the unstructured environments. When the continuous-track type mobile platform travels on terrain such as sand, gravel, stairs and etc., slippage occurs and thus the driving state of the mobile robot cannot be recognized normally. To compensate for this pose error, the proposed method utilizes optical flow estimation detected by camera. This method is tested through experiment. Finally, This method reduces the pose error detected on inertia measurement unit within some limit, while the pose error of without compensation increases without limit during robot move.

This paper presents a prototype of a three degree of freedom mannequin simulator for rehabilitation education. A three degree of freedom (shoulder 2, elbow 1) model which is similar to the human body is developed. In addition design of mathematical model with consideration about the resistance of muscles and ligaments is proposed. To apply ROM inspection method to the mannequin simulator, this paper introduces the PID controller of the mannequin simulator prototype with the ROM inspection method. Rehabilitation specialists verify the mannequin simulator with the ROM test method, and the validation experiments show that the simulator has “good” levels of similarity.

본 연구는 라오스 산촌마을의 기초 소득을 조사·분석하여, 지속가능한 대나무 자원을 활용한 새로운 소득 모델의 효과성을 제시하고자 하였다. 연구 대상지는 비엔티안 캐피털 주의 쌍통군 농부아 마을로써 산림과 벼농사지역이 혼재된 자급자 족형 논농사 위주의 마을이다. 농부아 마을은 과일, 야채 등 상업적 영농활동은 전무하여, 단순한 소득체계를 가지고 있다. 우기(6월~11월)는 천수답 벼농사에 의존하고 있고, 건기(12월~5월)는 가축 판매 또는 대나무 벌채를 통한 수익체계로, 2018년 농부아 마을의 기존 소득은 평균 1,456 달러로 분석되었다. 라오스 1인당 GDP (2018)가 2,690 달러와 비교할 때, 농산촌 지역의 소득은 GDP의 약 절반가량 수준 이다. 쌍통군 지역의 대나무 수종은 젓가락, 이쑤시개 등 원자재로서 베트남 가공회사로 판매되고 있다. 가공회사는 수익을 위해 수요량에 따라 마을 주민을 고용하여 다량의 대나무를 벌채하고 있다. 이러한 대나무벌채는 빠르고 수익성은 있지만, 회사 수요(농한기 한정)에 따라 비정기적으로 마을주민을 고용(하루 고용비용 $ 11; 고용시간 8시간)하며 노동 강도가 높 다. 또한 대나무 자원의 지속가능한 이용에도 한계가 있다. 이러한 조건에서 마을주민의 대나무 단순벌채로 인한 연 소득은 $ 552로 분석되었다. 소규모 마을 주민을 대상으로 대나무를 이용한 지역상품을 개발·생산하여 기술전수 및 판매를 시범적으로 실시하였다. 대나무 벌채와 비교하여 적은 양의 대나무를 이용하여 고부가가치를 창출할 수 있으며, 노동 강도가 높지 않아서 여가시간에 작업공정이 가능하다. 표본 10 가구의 생산량은 초기단계에서 하루 최대 6개가 생산가능하며, 제품 단위가격을 $ 2.3로 책정할 때, 연 소득은 $ 1,160 으로 분석되었다. 기존 모델의 소득(농업+대나무 벌채)은 평균 $ 1,456이며, 신규모델의 소득(농업+대나무 공예품)은 평균 $ 2,064로 신규 소득이 $ 608 높게 나타났다. 기존소득과 신규소득의 농업 수 입이 동일한 조건이므로, 소득에 차이를 주는 요인은 대나무 수입으로 신규 소득의 평균 $ 2,064가 기존 소득인 $ 1,456 보다 약 42% 증가된 수치로 나타났다.

주암호의 복교지점에서 2000년의 여름성층은 태풍 Prapiroon에 의해 파괴되었다. 성층의 파괴는 수체의 물리, 화학적 성질을 바꾸고 생물상의 변화를 유발시켰다. 투명도는 태풍 전에는 195 cm였는데 태풍 후 84 cm로 줄었는데, 이는 강한 바람에 의한 수체의 수직혼합으로 저층의 퇴적물이 부유되면서 투명도를 감소시킨 때문으로 추측된다. 식물플랑크톤 개체수의 수직분포에서는 태풍 전에는 수심 2 m에서 최대의 개체수가 조사되었었지만 태풍 직후에는 특정 수심의 peak가 없이 전 수층에 고른 분포를 하다가 재성층이 이루어진 후 다시 표수층>수온약층>심수층의 분포를 보여주었고 최고의 개체수는 수심 1 m에서 관찰되었다. 식물플랑크톤의 탄소생물량도 수심 2 m 부근에서 가장 많다가 태풍 직후에는 전 수층에 고루 분포하였고, 재성층 후 다시 표층에 가장 높은 생물량을 보여주었다. 클로로필 a의 농도는 태풍 전후에 큰 차이가 없는 것으로 나타났다. 태풍에 의한 성층과 재성층은 식물플랑크톤의 분류군 조성도 변경시켰는데, 태풍 전의 주요 우점 식물플랑크톤은 Aulacoseira granulata를 비롯한 규조류였으나 태풍이 지나간 후 녹조류가 세포수와 생물량에서 규조류를 압도하였고, 이후 강우와 수온의 하강으로 성층이 교란되면서 Microcystis aeruginosa에 의한 남조류의 절대 우점으로 천이 되었다.

본 연구는 NaCl 농도가 수리취의 무기이온 함량, 효소활성, 광합성 반응 및 생장특성에 미치는 영향을 알아보기 위하여 수행되었으며, NaCl 농도는 4가지 처리로 조절하였다(0, 50mM, 100mM, 200mM). NaCl 처리농도가 증가할수록 최대광합성속도, 순양자수율, 탄소고정효율과 같은 광합성 활성이 감소하 였으나 수분이용효율은 증가하였다. 또한 엽면적, 엽건중, 엽면적비, 줄기길이 및 T/R율이 감소하였는 데 특히 100mM NaCl 농도조건에서 크게 감소하였다. 염분스트레스 처리시 이온유출량, H2O2 함량 및 지질과산화(MDA)가 증가하여 세포막의 피해가 커졌으나 염분스트레스에 대응하기 위해 삼투조절물질인 proline 함량도 유의적으로 증가하였고, 산화적 스트레스를 소거하기 위해 APX와 GR의 활성 역시 증가하였다. NaCl 농도가 증가할수록 엽과 뿌리의 Na 함량도 증가하였으나, Ca, K 및 Mg 함량은 이와 반대되는 경향을 보였다. 결과적으로 수리취는 비교적 염분 스트레스에 민감한 식물로 특히 NaCl 100mM에서 산화피해가 유의적으로 증가하는 것을 알 수 있었다.

The artificial insemination (AI) is one of the best assisted reproductive technologies for increasing reproductive capacity and facilitating the genetic improvement in farm animals. AI has been used in Uganda for over 60 years, but a small population of the total herd has been used. This study was conducted to investigate the efficacy of AI with estrus synchronization technique and to propose ways of improving the productivity of dairy farms through AI services in Uganda. In total, 78 cows from 11 dairy farms were selected for timed-AI. Synchronization was performed according to the ovsynch programs followed by AI using frozen semen from Korean Holstein (0.5 ml straws). Pregnancy rate was varying among farms (0-50%) and the overall pregnancy rate was 28.2%. Cows in luteal phase at the time of treatment was 40.0% whereas that in follicular phase was 20.8%. After treatment, cows that showed normal estrus signal were 45.5% (25/55). Abnormal estrus was categorized into pre-estrus (9.1%), cystic ovaries (21.8%), anestrus (18.2%) and delayed ovulation (5.5%), respectively. These results imply that an assured protocol for timed-AI should be developed to improve the productivity of dairy farms through AI services in Uganda.

Harmonic structure materials are materials with a core–shell structure having a shell with a small grain size and a core with a relatively large grain size. They are in the spotlight because their mechanical properties reportedly feature strength similar to that of a sintered powder with a fine grain size and elongation similar to that of a sintered powder with a coarse grain size at the same time. In this study, the tensile properties, microstructure, and stretchflangeability of harmonic structure SUS304L made using powder metallurgy are investigated to check its suitability for automotive applications. The harmonic powders are made by mechanical milling and sintered using a spark plasma sintering method at 1173 K and a pressure of 50 MPa in a cylindrical die. The sintered powders of SUS304L having harmonic structure (harmonic SUS304L) exhibit excellent tensile properties compared with sintered powders of SUS304L having homogeneous microstructure. In addition, the harmonic SUS304L has excellent stretch-flangeability compared with commercial advanced high-strength steels (AHSSs) at a similar strength grade. Thus, the harmonic SUS304L is more suitable for automotive applications than conventional AHSSs because it exhibits both excellent tensile properties and stretch-flangeability.

In this study, we analyzed the relationship between phytoplankton community and physicochemical factors in 12 lakes located in Jeollanam-do based on the data surveyed from March to November 2014. Totally, 297 species of phytoplankton were identified including 98 Bacillariophyceae, 148 Chlorophyceae, 23 Cyanophyceae and 28 other phytoplankton taxa. The standing crops ranged from 124 to 59,148 cells mL-1 and showed the highest in August with the increase of Cyanophycean cells. The self-organizing map (SOM) was optimized into 9×6 grid and was classified into 5 clusters based on the similarity of environmental factors and phytoplankton indices. The SOM results showed that phytoplankton communities had positive relationship with water temperature, SS, DO, BOD, TP and Chl-a, whereas low relationship with pH, TN, NH3-N, NO3-N, PO4-P and Conductivity. In Pearson’s correlation coefficient, relationship between environmental factors and phytoplankton communities showed similar results with SOM.

Alpine plants with a scarcity of pollinators in harsh environments have been believed to undergo selfing for reproductive assurance; however, contradictory evidence is also available. Snowmelt regimes in alpine areas function to change life history characteristics of alpine plants such as flowering time and duration; yet the effects of snowmelt regimes have never been tested in alpine plants in Korea. This study was conducted to investigate the dichogamy, mating systems, and flowering characteristics of Megaleranthis saniculifolia populations [early and late snowmelt plots (ESP and LSP, respectively)] in a subalpine area of Sobaeksan Mountain in Korea. M. saniculifolia exhibited incomplete protogyny in that despite early maturation of pistils, maturation times of pistils and stamens within flowers were partly overlapped. Control and hand-outcrossing treatments produced significantly higher number of follicles and seeds per flower than autonomous and handselfing treatments. Based on the aggregate fruit set, the auto-fertility index (AI) and self-compatibility index (SI) were 0.33 and 0.50, respectively. Snowmelt occurred 10 days earlier in ESP than in LSP, thereby ESP and LSP showed distinct differences with regard to flower longevity and season, but showing no difference in peak flowering dates. We concluded that M. saniculifolia is an incomplete protogynous and largely outcrossing plant requiring pollinator service. Temporal variation in snowmelt time and subsequent changes in flowering characteristics under climate change may further threaten the population persistence of M. saniculifolia which has already been designated as endangered species in Korea.

This paper presents development of the new haptic device for virtual wall collision test. Mathematical model of the proposed system considering virtual wall collision is developed and tuned by comparing force responses from simulation and experiment with free motion. To verify the effectiveness of the proposed model, a range of collision tests against virtual wall are accomplished, conditioned on different collision speeds to virtual wall. In addition, hybrid PI control scheme is applied to improve the performance of the proposed haptic system in virtual wall collision experiments.

This paper studies the effect of a playtykurtic excitation signal on fatigue life. In general, a vibration test uses an excitation signal having a normal distribution of kurtosis 3. However, a vibration signal generated in a product’s operation environment has usually a non-normal distribution. This paper uses ZMNL method to generate a playtykurtic excitation signal having the equivalent power spectrum density with a reference vibration profile. This paper proposes a method which uses a fatigue damage spectrum ratio for studying the effect of a playtykurtic excitation signal on fatigue life. The fatigue spectrum damage ratio is obtained by dividing a fatigue damage spectrum acquired using the acceleration profile in which all conditions are the same except for the kurtosis by a fatigue damage spectrum acquired theoretically. This paper shows that the signal of kurtosis less than 3 can increase the fatigue damage spectrum by more than 2 to 4 times compared to the signal of kurtosis 3 using the fatigue damage spectrum ratio.

OBJECTIVES: This study is to develop the optimum mixing proportions for cement concrete pavement with using recycled aggregates. METHODS: The mixture varied recycled coarse aggregates content from 50 % to 100 % to replace the natural coarse aggregates by weight. Tests for fundamental properties as a cement concrete pavement were conducted before and after hardening of the concrete. RESULTS: It was found that the variation in the amount of the recycled aggregate affected the compressive and flexural strength development, as well as the chloride ion penetration resistance. As the amount of the recycled aggregate content increased the compressive and flexural strength and the resistance to chloride ion penetration decreased. However, the resistance to freeze-thaw reaction was affected significantly. In addition, the gradation of the aggregate became worse and hence so did the coarseness factor as the recycled aggregate amount increased. CONCLUSIONS : The fundamental properties of the concrete with recycled aggregate does not seem to be appropriate when the recycled aggregate quality is not guaranteed up to a some level and its replacement ratio is over 50%. The optimized gradation of the aggregates should also be sought when the recycled aggregate is used for the cement concrete pavement materials.

본 연구는 동시출현단어(co-word) 분석을 이용하여 기술경영 분야의 연구 주제 네트워크를 구축하고, 핵심 연구 주제 및 연구 주제 간 상호연관관계를 도출한다. 동시출현 빈도수의 정규화를 통해 키워드 간 유사성을 도출하여 무방향 네트워크를 분석하는 기존연구들과는 달리 본 연구는 연관규칙분석(association rule)을 통해 키워드 간 신뢰도(confidence)를 도출하여 유방향 네트워크 분석을 수행한다. 2011～2014년 기술경영 분야 9 개 국제 학술지에 게재된 2,456개의 논문의 저자키워드를 대상으로 빈도수 상위 200개 키워드를 추출하고, 주제(THEME), 방법(METHOD), 분야(FIELD)의 세 가지 유형으로 키워드를 분류한다. 각 유형별 일원(one-mode) 네트워크를 구축하여, 함께 많이 연구가 이루어진키워드들을 찾아내고, 핵심 키워드를 도출한다. 또한 두 가지 유형의 키워드 간의 이원(two-mode) 네트워크를 구축하여, 연구 주제별로 함께 많이 활용된 방법 및 대상 분야를 탐색한다. 본 연구 결과는 최근 성숙기에 접어든 기술경영 분야의 연구 흐름 및 지식 구조를 키워드 수준에서 구체적으로 제시함으로써, 기술경영 분야 연구자들의 연구 주제 탐색 및 연구방향 설계에 활용될 수 있을 것으로 기대된다.

When working on electrical wiring and cable, Electrically insulated aerial work platforms must be used to prevent the electrocution hazards. Aerial work platforms with composition boom is able to increase the weight and height of the workspace due to the lightweight of boom. The aim of this paper is to clarify structural stability of 3 stage telescopic booms having an operator platform and an upper boom of composition(Fiber Reinforced Plastic) by comparing the general telescopic booms with steel material using computational analysis.

Osteochondroma is one of the most common benign tumors of the bone. Although osteochondroma is rarely seen in the facial region, it was reported that the cases occured in the mandibular region, especially around the condyle. Patients complain about malocclusion, temporomandibular disorders and facial asymmetry. The treatments of these cases include total condylectomy or local resection of the lesion. A 48-year-old man visited our hospital. His chief complaints were pain in the left temporomandibular joint (TMJ) and deviation of mandible during mouth opening. Panoramic radiograph showed an enlarged left condyle. A bony proliferation with benign sign was also observed in the computed tomography. Surgical treatment was done by removing the bony mass. Histologically, biopsy result was an osteochondroma. After surgery, there was reduced pain and normal mouth opening. Deviation of the mandible was also observed. We report a case of osteochondroma on the mandibular condyle and a review of literature about the surgical treatment.

Cu-Mn과 Cu-Zn 촉매를 침전제로 다르게 하거나, 금속의 몰비율, 소성온도를 다르게 하여 공침법으로 제조하였고 CO산화반응을 수행하여 혼합산화물 촉매에서 Cu, Mn과 Zn의 영향 및 소성온 도가 미치는 영향을 조사하였다. 촉매의 물리·화학적 특성을 알아보기 위하여 XRD, N2 흡착 및 SEM 의 분석을 수행하였다. Na2CO3로 침전시켜 270℃로 소성하여 제조한 2Cu-1Mn 산화물 촉매가 저온에 서 CO 산화반응 활성이 가장 좋았으며 2Cu-1Mn 산화물 촉매는 43 m2/g으로 가장 높은 비표면적과 촉매 활성을 나타내었다. XRD로 촉매의 결정구조를 분석하였을 때 Cu0.5Mn2.5O4의 결정구조를 갖는 촉 매는 낮은 활성을 보였다. 270℃에서 소성한 촉매가 좋은 활성을 나타냈으며 Pt 촉매와 비교하여도 저 온에서 CO산화반응이 더욱 우수함을 알 수 있었다.

The effect of weir construction (2009~2011) was investigated on algal bloom dynamics and surrounding conditions in the Youngsan River by analyzing the long-term (2001~2014) data provided by the Water Information System, Ministry of Environment. The data include chlorophyll a and water properties such as total suspended solids (TSS), ammonium (NH4 +), nitrate (NO3-), orthophosphate (PO43-), total nitrogen (TN), total phosphorus (TP) and DIN/DIP molar ratio collected from 12 stations along the channel of the river. Temporal variations were examined using data collected monthly from 2001~2014 and Box-Whisker plot was used to examine the difference in algal bloom dynamics between before (2006~2008) and after (2012~2014) the weir construction. Pearson’s correlation analysis was also used to analyze the correlation of parameters. The results showed that TSS affecting water turbidity increased during the construction but decreased especially at the stations located in the upper and middle regions of the river after the construction. Ammonium concentrations increased whereas the concentrations of other nutrients decreased after the construction inducing an increase in N:P molar ratio. Chlorophyll a decreased suddenly during the construction but increased clearly after the construction at the stations where TSS decreased. This indicates that algal blooms can develop in the Youngsan River due to a decrease in turbidity that increases light penetration in water column although the concentrations of nutrients such as orthophosphate were reduced after the weir construction.

Recently, the need of weight reduction has been required in automobile industry. In this paper, we aim to evaluate the composite sandwich panel to substitute original steel structure of commercial vehicle. The compressive and drum-peel tests were conducted to consider core materials and resin system of the sandwich panel. Based on the test, we decided the core reinforcement and matrix materials of the panel. As a result, the composite panel were composed of aluminum profile, glass fiber prepreg and aluminum honeycomb. We also confirmed the weight reduction ratio and structural safety compared to prior steel structure components by bending test and FEM simulation.