• Korean Journal of Ecology and Environment
• /
• v.45 no.4
• /
• pp.482-489
• /
• 2012

Visual monitoring is hard to apply on fish because they are living in a water system. To overcome this problem, acoustic telemetry, which is effective for underwater monitoring, is often used for studying fish behaviors, such as movement distance, route and patterns. In this study, in order to monitor the movement pattern of Squaliobarbus curriculus (family Cyprinidae), we used acoustic telemetry and identified the home range and movement distances. A total of nine individuals were released at two different locations: one is at the estuary barrage (Sc1~3) and the other is at the lower part of Baekjae Weir (Sc4~9), located in Geum River. Approximately, a 70 km section from the estuary barrage was investigated. Fish, which were released at the estuary barrage, utilized up to 12.7 km upstream as home range from the release site. At the lower part of Baekjae Weir, most of the fish moved and stayed within a 7.2 km downstream area, except for Sc6, which moved 53.4 km (linear maximum distance from release site) downstream from the release site. Relatively small sized fish (Sc7~9) did not show any movement. Accumulated movement distance significantly correlated with the standard length of S. curriculus ($r_s$=0.715, p=0.03). Moreover, the standard length of moving fish was significantly larger than that of not moving fish (Mann-Whitney U test, p=0.024). Therefore, the movement distance of S. curriculus has been correlated with fish size; movement distance was increased with the standard fish length. Although the sample size of monitored fish was small, various meaningful data were collected by acoustic telemetry. Consequently, this technique could be a method available for effectively monitoring the behavior and ecology of native Korean and endemic species.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.6
• /
• pp.201-208
• /
• 2014

In this paper, we propose the classifier structure design algorithm using DTW. Proposed algorithm uses DTW result to design the binary tree architecture based on the SVM which classify the multi-class data. Design the binary tree architecture for Support Vector Machine(SVM-BTA) using the threshold criterion calculated by the sum columns in square matrix which components are the reference data from each class. For comparison the performance of the proposed algorithm, compare the results of classifiers which binary tree structure are designed based on database and k-means algorithm. The data used for classification is 333 signals from 18 classes of underwater transient noise. The proposed classifier has been improved classification performance compared with classifier designed by database system, and probability of detection for non-biological transient signal has improved compare with classifiers using k-means algorithm. The proposed SVM-BTA classified 68.77% of biological sound(BO), 92.86% chain(CHAN) the mechanical sound, and 100% of the 6 kinds of the other classes.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2011.06a
• /
• pp.235-235
• /
• 2011

Lau basin of south Pacific, as an active back arc basin, is promising area bearing seafloor massive hydrothermal deposit that is located in a subduction zone between the Pacific ocean plate and Indo-Australian continental plate. Korea Ocean Research and Development Institute tracked from 2004 to 2006 the hydrothermal activity to the extension of the northeast Lau Basin, targeting seamount. hydrothermal activity by tracking was found hydrothermal evidences. In this study, Marine seismic survey was carried out in the Lau basin seamount of the possibility of hydrothermal deposit. In particular, Marine magnetic survey and seismic survey was carried out at the same time in TA-12 seamount and noise characteristics were found in the seamount. the main process of data processing is Bandpass filter, FK filter, Deconvolution for noise attenuation such backscatter and multiple reflections. the migration is performed to compensate for reflection points followed by seamount of a slope. In this study, bedrock and upper strata could be identified and in the Future, the comparative method with Multi Beam Echo Sounder(MBES) are likely to derive the correct velocity model, the marine magnetic survey results should be considered.

• Korean Journal of Environment and Ecology
• /
• v.29 no.3
• /
• pp.344-352
• /
• 2015

This study aims to identify the difference in the starting time of the dawn chorus of different species of birds and related environmental conditions. For this study, the bird songs were recorded every 2 hours a day starting from 2 hours before sunrise for a whole spring season (from April to June, 2014) in Korea. The recorded sounds were analyzed to find the starting time of each species' song by sonogram pattern using a sound analyzing program (Adobe Audition CC). To analyze the relationship between the environmental conditions and the time of the birdsong of each species, we collected the data of environmental conditions: daily precipitation, Julian date, time of sunrise and moonrise, temperature data and twilight time from the Korea Meteorological Office. As a result of this study, it was found that there are several statistical correlation between the starting time of the birdsong and environmental conditions (every environmental condition except daily precipitation and time of moonrise). Also, the difference of the starting time among each species were identified. The species were divided into 3 groups (early, mid and late) by their wake-up time. Ring-necked pheasant and yellow-throated bunting were categorized as 'Early' group and all woodpeckers were categorized as'Late' group. This study is significant as it first presented a classification of wild birds in Korea by the starting time of their dawn chorus. However, further studies are required to identify why each species to do their dawn singing at different times.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2003.05a
• /
• pp.244-245
• /
• 2003

고체나 액체 추진로켓에 비하여 하이브리드 추진 시스템은 작동조건의 안정성과 안전함등의 많은 장점을 가지고 있다. HTPB와 같은 고체연료는 제작 및 저장, 운송 그리고 장착상의 안정성을 가지고 있으며 하이브리드 로켓의 고체연료로의 산화제의 유입을 제어하면서 추력의 변화와 엔진내부의 연소중단과 재 점화를 용이하게 할 수 있다. 이러한 이유로 인하여 하이브리드 엔진은 좀 더 경제적인 장치로 기대를 모으고 있다. 그러나, 기존의 하이브리드 로켓 엔진은 고체 추진 로켓에 비하여 낮은 연료 regression 율과 연소효율을 가지는 단점이 있다. 이러한 단점을 해결하고 요구되어지는 추력값과 연료유량을 증가시키기 위하여 고체연료의 표면적을 증가시킬 필요가 있다. 기존의 하이브리드 엔진에서는 연료 그레인에 다수의 연소포트를 만들어 표면적을 증가시켰으나 이는 비 활용 공간의 증가와 추진제의 질량 및 체적분율의 상당한 감소를 초래한다. 지난 수십년간에 걸쳐 하이브리드 엔진에서 연료의 regression 특성 및 엔진 성능 향상을 위한 연구가 계속되어 왔으며 최근에 엔진의 체적 규제를 경감시키고 연료의 regression율을 향상시키기 위하여 선회유동을 이용하는 하이브리드 로켓 엔진들이 제안되고 있다. 이러한 선회유동을 가지는 하이브리드 로켓은 고체연료 그레인에 대하여 평행하게 유입되는 기존의 하이브리드 로켓에 비하여 고체연료 벽면에서의 대류열전달이 현저하게 증가하게 되어 아주 높은 고체연료의 regression율을 얻을 수 있는 이점이 있다. 선회유동 하이브리드 로켓의 연소과정은 고체 연료의 열분해과정, 대류 열전달, 난류 혼합, 난류와 화학반응의 상호작용, soot의 생성 및 산화과정, soot 입자 및 연소가스에 의한 복사 열전달, 연소장과 음향장의 상호작용 등의 복잡한 물리적 과정을 포함하고 있다. 이러한 물리적 과정 중 난류연소, 고체연료 벽면 근방에서의 대류 열전달 및 연소과정에서 생성되는 soot 입자로부터의 복사 열전달, 그리고 고체연료 열 분해시 표면반응들은 고체연료의 regression율에 큰 영향을 미친다. 특히 고체연료의 난류화염면의 위치와 폭, 그리고 비 예혼합 난류화염장에서 생성되는 soot의 체적분율의 예측은 난류연소모델, 열전달 모델, 그리고 regression율 모델에 의해 크게 영향을 받기 때문에 수치모델의 예측 능력 향상시키기 위하여 이러한 물리적 과정을 정확히 모델링해야 할 필요가 있다. 특히 vortex hybrid rocket내의 난류연소과정은 아래와 같은 Laminar Flamelet Model에 의해 모델링 하였다. 상세 화학반응 과정을 고려한 혼합분율 공간에서의 화염편의 화학종 및 에너지 보존 방정식은 다음과 같다. 화염편 방정식과 혼합분률과 scalar dissipation rate의 관계식을 이용하여 혼합분률과 scalar dissipation rate에 따른 모든 reactive scalar들을 구하게 된다. 이러한 화염편 방정식들을 mixture fraction space에서 이산화시켜서 얻은 비선형 대수방정식은 TWOPNT(Grcar, 1992)로 계산돼 flamelet Library에 저장되게 된다. 저장된 laminar flamelet library를 이용하여 난류화염장의 열역학 상태량 평균치는 presumed PDF approach에 의해 구해진다. 본 연구에서는 강한 선회유동을 가지는 Hybrid Rocket 연소장내의 난류와 화학반응의 상호작용을 분석하기 위하여 Laminar Flamelet Model, 화학평형모델, 그리고 Eddy Dissipation Model을 이용한 수치해석결과를 체계적으로 비교하였다. 또한 Laminar Flamelet Model과 state-of-art 물리모델들을 이용하여 선회 유동을 갖는 하이브리드 로켓 엔진의 연소 및 Soot 생성 및 산화과정을 살펴보았으며 복사 열전달이 고체 연료 표면의 regression율에 미치는 영향도 살펴보았다. 특히 swirl강도, 산화제의 유입위치 그리고 선회유동의 형성방식이 하이브리드 로켓의 연소특성 및 regression rate에 미치는 영향을 상세히 해석하였다.

• Environmental and Resource Economics Review
• /
• v.18 no.4
• /
• pp.653-693
• /
• 2009

Using the Korean environmental input output analysis, this paper provides the emission intensities of the chemicals, especially, the toxic and carcinogenic substances, by linking the structure of demand, and the policy mix to abate these substances emissions. Acording to the results, Industries with the highest total emission intensities(TEI) of toxic substances are ranked : Printing and reproduction of recorded media(21), Other transportation equipment(26), Pulp and paper(11), Leather and fur products(9), Fiber yarn and fabrics(7). And the highest TEI of carcinogenic substances are Wood and wooden products(10), Motor vehicles and parts(25), Plastic and rubber products(15), Audio, video and communications equipment(23), etc.. The economic factors of changing these emissions are emission intensities and final demands. The effective combinations of policy instruments to abate these emissions are varied by the industries and substances. For example, Government need to execute the effective TEI management in the Fiber yarn and fabrics(7) sector, and, in furniture(27) sector, the reduction of final demand is more effective.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.116-116
• /
• 2007

21 세기에 접어들면서 인터넷을 통한 정보 통신의 발달과 개인 휴대용 이동 통신기기의 활발한 보급에 따라 휴대형 전자기기들의 소형화와 고성능화로 나아가고 있다. 이러한 전자기기에 사용될 IC의 내장 메모리 또한 집적화 및 고속화, 저 전력화가 이루어져야 한다. 이러한 전자기기들에 필수적인 압전 세라믹스 부품 중 압전 부저 및 기타 음향 부품등을 각종 전자기기와 무선 전화기에 채택함으로써 압전 부품에 대한 수요와 생산이 계속 증가할 것으로 전망된다. 이처럼 압전 세라믹스를 이용한 그 응용 범위는 대단히 방대하며, 현재 모든 압전 부품들은 PZT 계열 재료로 만들어지고 있고, 차후 모두 비납계열 재료로 대체될 것이 확실시된다. Pb의 환경오염은 이미 오래전부터 큰 문제점으로 인식되고 있었으며 그 일례로 미국의 캘리포니아 주에서는 1986년부터 약 800종의 유해물질, 그 중에서도 Pb 사용을 300ppm 이하로 규제하는 Proposition 65를 제정하여 실행하고 있다. 그리고 2003년 2월에 EU (European Union) 에서 발표한 전자산업에 관한 규제 사항중 하나인 위험물질 사용에 관한 지칭 (Restriction of Hazardous Substance, RoHS) 에 의하면, 2006 년 7월부터 전기 전자 제품에 있어서 위험 물질인 Pb을 포함한 중금속 물질(카드늄, 수은, 6가 크롬, 브롬계 난연재)의 사용을 금지한다고 발표하였다. 비록 전자세라믹 부품에 함유된 Pb는 예외 사항으로 두었지만 대체 가능한 물질이 개발되면 전자세라믹 부품에서도 Pb의 사용을 금지한다고 규정하였다. 더욱이 일본은 2005 년부터 Pb 사용을 금지시켰다. 이와 같이 Pb가 환경에 미치는 영향 때문에 비납계 강유전 물질 및 압전 세라믹스 재료에 대한 연구가 전 세계적으로 활발히 진행되고 있다. 본 연구에서는 비납계 강유전체의 patterning을 위해서, NKN 박막을 고밀도 플라즈마원인 ICP를 이용하여 식각 mechanism을 연구하고, 식각변수에 따른 식각 공정을 최적화에 대하여 연구하였다. 가스 혼합비에 따라 식각 할때 700 W의 RF 전력과 - 150 V의 직류 바이어스 전압을 인가하였고, 공정 압력은 2 Pa, 기판 온도는 $23^{\circ}C$로 고정하였다. 식각 속도는 Tencor사의 Alpha-step 500을 이용하여 측정되었으며 식각 시 NKN 박막 표면과 라디칼과의 화학적인 반응을 분석하고 식각 메커니즘을 규명하기 위하여 XPS(x-ray photoelectron spectroscopy)를 사용하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.8 s.113
• /
• pp.864-871
• /
• 2006

In the development of electricity generating wind turbines for wind farm application, only two types have survived as the methods of power regulation; stall regulation and full span pitch control. The main purpose of this paper is to experimentally identify the characteristics of noise emission of wind turbines according to the power regulation types. The sound measurement procedures of IEC 61400-11 are applied to field test and evaluation of noise emission from each of 1.5 MW and 660 kW wind turbines (WT) utilizing the stall regulation and the pitch control for the power regulation, respectively. Apparent sound power level, wind speed dependence, third-octave band levels and tonality are evaluated for both of WTs. It is observed that equivalent continuous sound pressure levels (ECSPL) of the stall control type of WT continue to increase with increasing wind speed whereas those of the pitch control type of WT show less correlation with wind speed. These observed characteristics are believed to be due to the different airflow patterns around the blade between the stall regulation and the pitch control types of WT; the airflow on the suction side of blade in the stall types of WT are separated at the high wind speed. It is also found that the 1.5 MW WT using the stall control emits lower sound power than 660 kW one using the pitch control at wind speeds below 8m/s, whereas sound power of the former becomes higher than that of the latter in the wind speed over 8m/s. This wind-speed dependence of sound power leads to the very different noise omission characteristics of WTs depending on the seasons because the average wind speed in summer is lower than 8m/s whereas that in summer is higher. Based on these experimental observations, it is proposed that, in view of environmental noise regulation, the developer of wind farm should give enough considerations to the choice of power regulation of their WTG based on the weather conditions of potential wind farm locations.

• Korean Journal of Environment and Ecology
• /
• v.33 no.6
• /
• pp.664-676
• /
• 2019

This study aimed to analyze the bioacoustics and habitat environment of the cicadas inhabiting Taebaeksan National Park, an sub-alpine region in Korea. The mating calls of the cicadas were recorded for approximately 3 months, between July and September of 2018. The recording devices were installed in Daedeoksan valley and Baekcheon valley, inside Taebaeksan National Park, and the sounds were recorded 24 hours a day. In order to obtain the habitat distribution data of the cicadas, the sounds were recorded from 111 spots located in the Taebaeksan National Park trail in August 2018. The daily weather data was obtained from the Taebaek city weather center. The results of the study demonstrated that 5 species of cicadas inhabit Taebaeksan National Park, namely, Leptosemia takanonis, Lyristes intermedius, Kosemia yezoensis, Hyalessa fuscata, and Meimuna opalifera. The time of appearance for L. takanonis was early July to mid-July, and that for L. intermedius, K. yezoensis, H. fuscata, and M. opalifera was mid-July to early September. Analysis of the circadian rhythm revealed that L. intermedius, K. yezoensis, and H. fuscata started producing mating calls between 6:00 and 7:00, which ended at around 19:00 for all the three species. The peak time for producing mating calls was 11:00 for L. intermedius, 12:00 for H. fuscata, and around 13:00 to 14:00 for K. yezoensis. The environmental factors influencing the mating calls of the cicadas inhabiting Taebaeksan National Park were analyzed by logistic regression. The results showed that the probability of producing mating calls increased by 1.192 and 1.279 times in L. intermedius and K. yezoensis, respectively, when the average temperature increased by one degree. When the duration of sunlight increased by one hour, the probability of producing mating calls increased by 4.366 and 2.624 times in L. intermedius and H. fuscata, respectively. Analysis of the interspecific effects revealed that when H. fuscata produced a single mating call, the probability of producing mating calls increased by 14.620 and 2.784 times in L. intermedius and K. yezoensis, respectively. When K. yezoensis and L. intermedius produced mating calls, the probability of producing mating calls in H. fuscata increased by 11.301 and 2.474 times, respectively. L. intermedius and K. yezoensis did not have any effects on each other with respect to the production of mating calls. Analysis of the habitat environment of each species revealed that their habitats were located at altitudes of 1,046 m (780~1,315 m) for L. intermedius, 1,072 m (762~1,361 m) for K. yezoensis, and 976 m (686~1,245 m) for H. fuscata. Unlike H. fuscata, which was found at a low altitude, K. yezoensis and L. intermedius were not found at altitudes lower than 700 m. Analysis of the average aspect of the habitats of each of the cicada species revealed that L. intermedius was found at 166° (125~207°), K. yezoensis was found at 100° (72~128°), and H. fuscata was found at 173° (118~228°). Examination of the distribution of each of the cicada species revealed that they were predominantly distributed in the ridges and slopes located in the southeastern region of Munsubong in Taebaeksan. In summary, L. intermedius and K. yezoensis was found to inhabit higher altitudes in Taebacksan National Park than H. fuscata, which was found throughout the Korean peninsula. Additionally, the main aspect of the cicada habitat was found to be the southeastern region (100~173°), which has good access to daylight.

• Journal of Chest Surgery
• /
• v.38 no.7 s.252
• /
• pp.496-500
• /
• 2005

There was no difference between the bileaflet mechanical valves on the midterm and longterm clinical outcome. We reviewed the hemodynamic comparison between recently available mechanical valves by Doppler Echocardiography. Material and Method: We retrospectively reviewed 396 postoperative hemodynamic datas (EOA, MDPG, and MSPG) by doppler echocardiography in 345 patients. Mechanical valves from 5 venders (Sorin Bicarbon, SJM, ATS, On-X, and Edward MIRA) were compared. There were 232 valves in mitral position, 162 in aortic, and 2 in tricuspid. Result: There were 178 men (mean age; $50.6\pm13.9$ years old) and 167 women $(52.6\pm,4.6)$. MDPG/EOA of 27 mm in mitral position was Sorin; $4.2\pm1.5 mmHg/3.0\pm0.9cm^2,\;SJM;\;2.3\pm1.2/3.5\pm0.6$. In 29mm, Sorin, SJM, ATS, On-X, MIRA revealed $3.4\pm1.2/3.1\pm0.6,\;3.3\pm1.1/2.7\pm0.4,\;3.8\pm0.8/3.2\pm0.6,\;4.0\pm3.0/3.1\pm0.9,\;2.9\pm0.9/3.0\pm0.8$ In 31mm, Sorin, SJM, ATS, MIRA revealed $3.9\pm1.9/2.9\pm0.6,\;3.5\pm1.2/3.0\pm0.6,\;3.4\pm0.8/2.8\pm0.2,\;3.7\pm1.5/2.7\pm0.7$. In 33mm, Sorin, SJM, MIRA revealed $4.4\pm0.9/2.5\pm0.4,\;3.4\pm1.5/3.3\pm0.5,\;4.7\pm2.4\3.0\pm0.3$. MSPG/EOA of 19mm aortic position was Sorin, SJM, ATS, On-X, MIRA $18.0 mmHg/1.2cm^2,\;25.6\pm8.7/1.1\pm0.3,\;25.9\pm12.6/1.2\pm0.3,\;23.0/1.3,\;27.9\pm7.1/1.2\pm0.1$ in that order. In 21mm, SJM, ATS, On-X, MIRA revealed $18.3\pm6.7/1.5\pm0.5,\;13.7\pm2.1/1.7\pm0.3,\;17.0/1.4,\;17.1\pm5.5/1.8\pm0.5$. In 23mm Sorin, SJM, ATS, On-X, MIRA revealed $14.0\pm4.6/1.7\pm0.6,\;12.8\pm3.2/2.0\pm0.2,\;16.8\pm12.2/2.1\pm0.9,\;14.0/1.5,\;15.0\pm5.5/1,8\pm0.5$. In 25mm, SJM and MIRA revealed $14.0\pm5.1/1.8\pm1.0,\;11.0/2.3$. There was no statistically significant difference in these values between the venders given the same position and size. 2 redo valve replacements were performed, 1 due to severe hemolysis in ATS and 1 due to leaflet immobilization in SJM. Conclusion: Postoperative hemodynamic comparison by doppler echocardiography shows no statistically significant difference between recently available mechanical valves in this country.