Search

In this study, we set out to determine the cascade effects of slope gradient on ground vegetation and small-rodent populations in a forest ecosystem. We focused on two forest-dwelling small rodents with different habitat requirements, the striped field mouse Apodemus agrarius (preferring dense ground vegetation) and the Korean field mouse A. peninsulae (dense forest and woodland). The study area comprised natural deciduous forests and Japanese larch Larix kaempferi plantations in South Korea. The abundance of A. agrarius but not that of A. peninsulae was related to slope gradient. There was a negative effect of slope gradient on ground vegetation coverage and a positive effect of ground vegetation on A. agrarius populations. Our results highlight that the population of A. agrarius was indirectly influenced by the negative effects of slope gradient on ground vegetation. Slope gradient can, therefore, be a limiting factor in the microhabitats occupied by small rodents. This study reveals a critical role for slope gradient since it can modify not only microhabitat conditions, but also small-rodent populations, and this finding can contribute to improved microhabitat management.

Background: Behavioral traits of pigs have been shown to be partly under genetic control, which raises the possibility that behavior might be altered by genetic selection, resulting in pigs with better growth performance. Objective: To evaluate the behavior and growth of finishing pigs and investigate pigs selected for high or low social breeding value (SBV) in relation to social behavior and group growth. Methods: Thirty-five females and 35 boars from five positive and five negative SBV groups of finishing pigs were grown from 30 to 90 kg and housed in 10 test pens (3.0 × 3.3 m, 7 pigs/pen). Pigs were recorded with video technology for nine consecutive hours on days 1, 15, and 30 after mixing. Pigs were weighed at approximately 90 kg body weight and the number of days to reach 90 kg was then calculated. Results: The frequency and duration of behaviors were present in the positive and negative SBV groups after mixing. On day 1 after mixing, agonistic behavior was significantly higher (p=0.027) for the –SBV group compared with the +SBV group. Feeding and feeding-together behaviors were significantly higher (p

Forestry practices can lead to changes in wildlife habitat that could have lasting effects on the distribution of species. Hence, the aim of this study was to determine the effects of forestry practices on habitat variables and habitat use by mammals in three different stands (control, clear-cut and clear-cut with reserves) in a Japanese larch Larix kaempferi plantation from April to October in 2016 and 2017. We recorded the presence of field signs for the following six mammal species: Korean hare Lepus coreanus, raccoon dog Nyctereutes procyonoides, Eurasian badger Meles meles, water deer Hydropotes inermis, roe deer Capreolus pygargus and wild boar Sus scrofa. Habitat variables significantly differed among three stands. Field sign (feces, foot prints and feeding signs) abundances of mammals showed significant differences between the control and clear-cut stands. Moreover, field sign abundances of all species were highest in the clear-cut with reserves stand. We calculated the impact of clear-cutting on habitat use by mammals using GLMMs. Both clear-cutting in the models were significant and had positive coefficients on habitat use by Korean hare, raccoon dog, deer and wild boar. In Eurasian badger models, only clear-cutting with reserves show positive impacts on habitat use. Habitat selection by forest edge species such as Korean hare and deer showed dependence on understory structure. Abundant understory in the clear-cut with reserves stand may not only provide vegetative food and cover for herbivores but also small prey species for omnivores and carnivores. The results of our study show that forest understory is one of the most instrumental factors mitigating the effects of clear-cutting on habitat use by mammal and it should, therefore, be given due importance in forestry practices.

Objective This study was conducted to characterize the behaviors and the body weight of suckling piglets in different social environments. Methods Two groups of sows and suckling piglets housed either in individual farrowing crates in separate pens (1.8×2.4 m, the control group) or in groups of three sows with their piglets in farrowing crates in a large common enclosure (5.4×2.2 m, the treatment group) were observed with the aid of video technology for 9 consecutive hours on days 1, 2, and 3, after mixing. Results Suckling, agonistic, and elimination behaviors of suckling piglets were significantly higher in the control group than in the treatment group. Inactive behavior was higher in the treatment group than in the control group. Most of the effects of the social environment on the suckling piglets seem to be the result of large reductions in behaviors and body weight for piglets switching from high activity to low activity. Moreover, suckling behavior and birth body weight were highly correlated with body weight at the end of the test. Conclusion The social environment that resulted from mixing, thus, had significant effects on the behavior and body weight of suckling piglets, and behavioral characteristics, therefore, should be considered when making improvements to the husbandry and care methods used in swine production.

The present study was conducted to elucidate the movement and home range of 7 subadult cinereous vultures Aegypius monachus during the wintering and summering periods using a telemetry system from January 2015 to March 2017 in East Asia. In total, 7053 locations (180?1607 points per bird) were used to analyze the home range size and movement distance of the birds during the wintering, migration, and summering periods. The tracked birds overwintered in South Korea. They migrated between South Korea and Mongolia during spring and autumn, respectively. Their movement and home range size varied considerably throughout the annual cycle between the wintering and summering grounds. The migration route and home range exhibited considerable overlap among the vultures tracked. Further studies on breeding ecology and habitat use pattern are necessary for the conservation of cinereous vultures and their habitats in the wintering and summering grounds.

This study was conducted to investigate the influence of atmospheric factors on the body and egg of great tits (Parus major), which were bred in artificial nest boxes from March to July of 2012 and 2013. The mean temperature and relative humidity were significantly higher in the spring season of 2012 than in 2013. Body masses of incubating parent birds differed between both years. Eggs which were laid in 2012 were larger and heavier than those of 2013. Hue and saturation values for background and spot colors were significantly different between 2012 and 2013. In 2012, there were warmer and wetter atmospheric conditions, which may influence vegetation and food availability for the birds. The large, heavy, and less vividly-colored eggs were laid in 2012 by parents with good body condition. Results showed that spring atmospheric factors influenced both body and egg of great tits. Further studies on the relationships between atmosphere, vegetation, and food availability of the birds are needed.

With regard to animal welfare concerns, behavioral information of weaned and mixed piglets is great interest in swine production. The aim of this study was to demonstrate the change in behavior of weaned piglets over time in two different groups (littermates and piglets from different litters) after mixing. Two weaned groups of piglets (72 individuals in all) housed either with littermates or with foreign piglets (6 individuals in 1.8 mx1.4 m pens, 28 degrees C +/- 1 degrees C temperature) were observed with the aid of video technology for 9 consecutive hours on days 1, 2, and 3 after mixing. The behaviors of the weaned piglets in the control and treatment groups were significantly different among the days after mixing. Piglets were, however, more active and aggressive in the groups with foreign piglets. This study reveals a lower level of agonistic behavior in groups of piglets that came from the same litter.

This study was conducted to examine the bill color and body mass of great tit (Parus major) nestlings in artificial nest boxes. In this study, the nestlings with yellow bills had a higher body mass on the second and eighth day after hatching. Moreover, the brightness values of the color of the bill on the eighth day after hatching were negatively correlated with the body mass of the chicks. Our experiment shows that the color of the bill of the nestling could accurately signal the quality of the chick. Moreover, carotenoid-based colors play an important role in avian communication. Study of carotenoid-based colors in the great tit would be required in the future.

We examined the ecological factors influencing winter abundance of mammals in the natural deciduous forest and the Japanese larch, Larix leptolepis, plantation in Mount Maehwa, Hongcheon, South Korea. We counted the tracks of five mammal species — the Korean hare, Lepus coreanus; the raccoon dog, Nyctereutes procyonoides; the Siberian weasel, Mustela sibirica; the water deer, Hydropotes inermis and the wild boar, Sus scrofa — in the snow from November 2013 to February 2014. We showed that the mean basal area, canopy cover and shrub cover were significantly higher in the Japanese larch plantation than in the natural deciduous forest. The winter abundances of Korean hares, raccoon dogs and water deer were higher in the Japanese larch plantation than in the natural deciduous forest. The results of stepwise analysis revealed that the winter abundances of four species were significantly correlated with ≥ 1 of the habitat variables. The winter abundances of Korean hares, water deer and wild boars were significantly correlated with shrub cover. The winter abundances of Korean hares, raccoon dogs and wild boars were significantly correlated with fallen logs; and the winter abundance of water deer was significantly correlated with canopy cover. For all of the investigated species, the preferred winter habitat was the Japanese larch plantation, with dense shrub cover and high number of fallen logs. Our results indicate that for planning conservation and forest management strategies for mammal species, the preferred forest habitat variables must be taken into consideration.

In this paper, we address the design, fabrication and test of a qualification model of a wire thermal cutting based non-explosive actuation (NEA) device for a small satellite. The important design parameters such as maximum allowable preload and release time are investigated through theoretical analysis. After it is fabricated based on theoretical results, we implemented the mechanical performance tests to assure operability and reliability for the compact size NEA device. From the result of the mechanical performance tests such as maximum preload, shock level and release time tests, we found that the proposed NEA device can be operated under a preload of 1000 kgf within 550 ms stably and it generates a low shock of 58.57 G. The margin calculation shows that the proposed NEA device can hold a solar panel of 20 kg with a margin of safety ( MS) of +0.32. In addition, we carried out the environment tests such as the vibration test and thermal vacuum test to qualify the proposed NEA device. From the vibration test, we found the resonant shapes after sine and random vibration were the same which means the proposed NEA device was successfully designed to have a stable structure. From the result of the thermal vacuum test, in addition, the proposed NEA device was well operated in a space environment condition.

This study was conducted to clarify the characteristics of bat populations in lowland dry evergreen forests of the Central Cardamom Protected Forest in Cambodia during the rainy seasons of 2011–2013 and the dry seasons of 2012–2013. In five study sites of the forest, data from 160 individuals of six bat species were recorded. The Sunda short-nosed fruit bat (Cynopterus brachyotis Sunda) was the most dominant species in all study sites. Most captured bats were adults, and captured females outnumbered captured males. In this study, populations of the bats, except for that of the Sunda short-nosed fruit bats, were not stable. Therefore, forest loss and degradation should be prohibited in the study areas to ensure stable bat populations. Further studies are required to investigate the ecological characteristics of fruit bats in various forest types for the conservation of the mammals and their habitats.

본 연구는 침엽수림과 활엽수림에서 양서류와 파충류의 개체군 특성 차이를 파악하기 위해 2013년 7월부터 9월까지 강원도 홍천군 일대의 국유림에서 실시되었다. 임상별 산림의 수직구조를 파악한 결과, 관목층(1~2 m)과 아교목층(2~8 m), 수관층(20~30 m)의 엽층별 피도량은 침엽수림이 활엽수림에 비해 더 크게 나타났으나, 흉고직경분포는 유의한 차이를 보이지 않았다. 침엽수림과 활엽수림에 각각 2개 조사구, 총 4개 조사구 내에서 월별 1회씩 총 12번의 선형횡단조사를 통해 양서류는 4종 52개체, 파충류는 3종 11개체가 확인되었다. 임상에 따른 양서류와 파충류의 평균 종수와 개체수, 평균 종다양도 차이를 파악한 결과 유의한 차이를 보이지 않았다. 임상별 각 종의 평균관찰 개체수를 파악한 결과, 청개구리는 침엽수림에서만 관찰되었고 도롱뇽과 아무르장지뱀, 대륙유혈목이는 활엽수림에서만 서식이 확인되었으나 통계적으로 유의한 차이는 나타나지 않았다. 향후 임상에 따른 양서류와 파충류의 개체군 특성을 파악하기 위해서는 보다 장기적이고 정밀한 모니터링이 지속적으로 이루어져야 할 것으로 판단된다. 【This study was conducted to clarify the characteristics of amphibian and reptile (herpetofauna) populations in a coniferous plantation and a deciduous forest from July to September 2013 in national forest, Hongcheon, Gangwon province, Korea. Coverage of understory, mid-story and overstory were more developed in a deciduous forest. We used line transect sampling method on a total of 4 transect lines, 2 lines in each forest type. Fifty two individuals of 4 amphibian species and 11 individuals of 3 reptile species were recorded. Mean observed number of herpetofauna species, individuals and species diversity index (H') were not significantly different between coniferous plantation and deciduous forest. This result related to ecological characteristics of herpetofauna. Habitats of herpetofauna were influenced on not only vertical structure of forests, but also climatic variables, thermoregulation and prey availability. The long-term monitoring and research on habitat preference and seasonal ecological traits of herpetofauna would be needed for conservation and management of herpetofauna in forest areas.】

In this paper, we present a compact non-explosive actuator device (NEA) that is activated with a thermal cutting method using Ni-Cr wire. Practical applications include the deployment of satellite appendages such as solar array panels and antennae. The pyrotechnic based separation device generates high shock and chemical contaminants, which cause malfunctions of components such as optic cameras and other sensors. The proposed NEA device is designed to generate low shock using unspool mechanism characteristic, and to have compact dimensions and a light mass. In the design process, we formulated equations based on a static analysis to verify that it satisfied the basic requirements. Then we fabricated the device based on a theoretical analysis and carried out pre-tests such as maximum preload and response time tests to verify the results of the theoretical analysis. The pre-test results showed an average maximum preload of 1,000 kgf and a response time of 600 ms. Consequently, we verified the feasibility of an NEA that could be activated within 600 ms under high preload. In order to develop a qualification model for the NEA, various additional tests are planned, including launching and space environment tests based on the European Satellite Agency standard test manual.

This study was conducted to clarify the effects of begging call playbacks on the growth of great tit, Parus major, nestlings in artificial nest boxes. The mean body mass of nestlings significantly differed between the control (60 dB playback intensity), playback 1 (80 dB), and playback 2 (100 dB) groups. However, mean tarsus length was not different based on treatment. The daily body mass and tarsus length gain of nestlings in playback 2 were higher than in the control and playback 1 groups in this study. Further long-term research is needed to understand the relationship between begging behavior of nestlings and parental care in the great tit.

This study was conducted to elucidate the breeding ecology of tits in artificial nest boxes in both deciduous and coniferous forests located in Mt. Namsan, Seoul Metropolitan, Korea, from March to June 2012. Great tit Parus major and varied tit P. varius both used the artificial nest boxes in the coniferous forest, but only the great tit used the artificial nest boxes in the deciduous forest for breeding. There were 27 artificial nest boxes in the coniferous forest and 17 in the deciduous forest. The rate of breeding success was 6.7–26.7% for both study sites. The clutch size of varied tits was less than that of great tits. Brood size, incubation period and nestling care period were the same for great and varied tits in the coniferous forest. There were no differences related to forest type for number of breeding pairs, breeding behaviors, egg measurements, and results of hatching, fledgling and breeding for great tits bred in artificial nest boxes. Long-term ecological research on food availability and b...

The goal of this study was to gain an understanding of small mammal populations in thinned and clearcut stands in Japanese larch (Larix leptolepis) plantations on Mt. Maehwasan, Hongcheon, Korea. Foliage profiles, diameter at breast height distribution, coverage of ground, and volume of coarse woody debris were significantly different between thinned and clearcut stands. Total number of captured small mammals, number of captured striped field mice, and mean striped field mouse population densities obtained from Jolly–Seber estimates were higher in clearcut stands. Coverage of ground, volume of coarse woody debris, and number of downed trees were critical variables for abundance of small mammals in this study. Our results suggest that retention of coarse woody debris and downed trees prevent reduction of small mammal populations after forest practices in Japanese larch plantations.

We present a kevlar rope based Non-Explosive Actuator(NEA) device which has simple structure and is activated by burning Ni-Cr wire. Through performance test, we find it can be operated under various pre-load by simply changing turn number of Ni-Cr wire. It shows release time of 680ms and shock level of 110G under pre-load of 6.0kN. Launching environment and space environment tests are planned to verify performance of the NEA based on European Satellite Agency test manual. Conclusively, we expect the proposed NEA can be applicable to release solar panel and fairing separation.

We examined the influence of tree thinning on the abundance of mammals in a Japanese larch Larix kaempferi plantation in Mt Gariwang, Pyeongchang, South Korea. In 2014 and 2015, from April to October, we recorded the presence of tracks as a proxy for abundance, for the following seven mammalian species: Korean hare Lepus coreanus, raccoon dog Nyctereutes procyonoides, Siberian weasel Mustela sibirica, Eurasian badger Meles meles, water deer Hydropotes inermis, roe deer Capreolus pygargus, and wild boar Sus scrofa. We also assessed how the intensity of tree thinning affected vegetation cover; there were significant differences in number of standing trees, basal area, coverage of vegetation layers, and number and volume of downed trees among the control, moderately thinned, and intensively thinned stands. We found significant differences in the abundance of tracks among the stands for three mammal species. In four mammal species, the abundance of track was significantly correlated with volume of downed trees, coverage of ground vegetation, number of downed trees, and number of standing trees, according to stepwise analysis. The presence and abundance of mammals is linked to habitat variables and forest managers should consider how habitat modifications will affect wildlife.

A non-explosive separation device using a screw jack mechanism is designed, fabricated and tested for a small satellite. In order to activate the proposed device with a small amount of torque, we employ a double actuation mechanism which is initially triggered by a piezo actuator and finally activated by a spiral spring. Through theoretical analysis and experimentation, the specifications of the spiral spring and piezo actuator to activate the separation device are determined. Owing to the novel design of the mechanism, it can be activated within 0.65 sec under 100 kgf with 0.45 kgf-cm of torque. Since screw jack mechanisms have commonly been used to upload heavy mass, and have self-locking capabilities under high load, a screw jack is also employed for the proposed separation device. Therefore, it can tolerate launching vibration as well as a thermal vacuum test without coming unfastened. The shock level is limited to 12 G, which is appropriate for a small satellite.

In this study, we investigated the effects of mixing on the aggressive behavior of commercially housed pigs. The behavioral patterns of 36 groups of pigs (a total of 360 animals) were observed over 3 consecutive days directly after weaning (25 +/- 1.2 days of age), and 25 and 50 days later with the aid of video technology. Fight latency and total duration and frequency of fighting were significantly different among the age groups. The aggressive behaviors decreased in 75-day old pigs if compared to 25- and 50-day old animals. Moreover, dominance index (DI) was higher in 25-day old and lower in 75-day old pigs. A comparison of dominant (DI>0) and submissive (DI

Precise time-of-arrival (TOA) estimation is one of the most important techniques in RF-based positioning systems that use wireless sensor networks (WSNs). Because the accuracy of TOA estimation is proportional to the RF signal bandwidth, using broad bandwidth is the most fundamental approach for achieving higher accuracy. Hence, ultra-wide-band (UWB) systems with a bandwidth of 500 MHz are commonly used. However, wireless systems with broad bandwidth suffer from the disadvantages of high complexity and high power consumption. Therefore, it is difficult to employ such systems in various WSN applications. In this paper, we present a precise time-of-arrival (TOA) estimation algorithm using an IEEE 802.15.4 ZigBee system with a narrow bandwidth of 2 MHz. In order to overcome the lack of bandwidth, the proposed algorithm estimates the fractional TOA within the sampling interval. Simulation results show that the proposed TOA estimation algorithm provides an accuracy of 0.5 m at a signal-to-noise ratio (SNR) of 8 dB and achieves an SNR gain of 5 dB as compared with the existing algorithm. In addition, experimental results indicate that the proposed algorithm provides accurate TOA estimation in a real indoor environment.