개에서 위운동에 관한 초음파 관찰

원현희,최민철,이효종 한국임상수의학회 2000 한국임상수의학회지 Vol.17 No.2

The Ultrasonographic method alas been widely applied to evaluating gastric motility with safety and reproducibility ill human medicine but few reference to its use in veterinary medicine is appeared. Therefore, in this study, the gastric motility was evaluated with ultrasonography by the cri-terion of mean cycle lime, short and lony axis and the area of pyloric antrum in dogs, fed with liquid of semisolid meals. Furthermore, the animals were evaluated for the effect of metoclopramide on the motility of pyloric antrum. Healthy 5 mongrel male dogs were fed with either 400 ml of milk a: a liquid meal or a mixed meal of 200 ml of milk with two pieces of bread as a semisolid meal. Mean cycle time of pyloric antrum of dogs was significantly delayed after feeding either of liquid and , semi- solid meals(P<0.05), alls it was returned to the fasting state at 60 min. after feeding of liquid meal and 160 min. after feeding of semisolid meal. Mean area of pyloric antrum of dogs was gradually decreased and was returned to the lasting state at 80 min. in doss fed liquid meal. but 1600 min. in dog\ulcorner fed semisolid meal. The administration of metoclopramide (1.0 mg/kg of of B.W.) accelerated the mean cycle time of pyloric antrum from 20 mill. to 60 min. after feeding of liquid meal and from 40 min. to 120 min. after feeding of semisolid meal. From this study, the ultrasonography was confirmed as a valuable diagnostic method leer evaluating the gastric motility and gastric area in dogs. It is non-invasive, safe and reproducible, and provides a method for the study of the effect of drugs and diseases states on gastric motility.

다중 GNSS 수신기를 위한 저전력 신호 획득 기법 설계 및 FPGA 구현

류영빈,원현희,정준우,강행익,권승복,오혁준 국제차세대융합기술학회 2023 차세대융합기술학회논문지 Vol.7 No.9

본 논문은 다중 GNSS 신호를 수신하기 위한 저복잡도를 갖는 신호 획득 기법을 제안하고, FPGA에 구현하기 위한 효율적인 구조를 제안한다. 기존 Binary Offset Carrier(BOC) 변조 기반의 GNSS 신호는 GNSS 수신기에서 다중 첨두 현상을 피하고자 최소 4배 오버샘플링이 필요하지만, 본 논문에서는 GPS와 GLONASS와 같이 최소 2배 오버샘플링만으로도 신호 획득 과정에서 다중 첨두 현상을 피해 충분한 정밀도를 얻을 수 있는 기법을 제안했다. 컴퓨터 시뮬레이션 결과, 기존 기법 대비 절반의 복잡도로 동일 성능을 얻을 수 있음을 보였으며 제안 기법을 기반으로 실제 구현을 위한 효율적인 구조를 제안하여 Verilog-HDL을 사용해 Xilinx Kintex-7 FPGA 보드에 구현하였다. 그 결과 기존 기법에 비해 하드웨어 자원 소모는 줄이고 성능은 동일함을 확인함으로써 제안 기법의 성능을 검증하였다. In this paper, a computationally efficient signal acquisition algorithm is proposed for acquiring Multi-GNSS signals, and a FPGA implementation structure with low complexity is also proposed. Existing Binary Offset Carrier(BOC) modulation-based GNSS signals require at least 4x oversampling to avoid multi-peak problem in GNSS receivers, but in this paper, we proposed a method to avoid multi-peak problem in signal acquisition processes with at least 2x oversampling such as GPS and GLONASS. Computer simulation results show that the same performance was obtained with half the complexity of the conventional method and based on the proposed method, an efficient architecture for actual implementation is propoces and implemented on the Xilinx Kintex-7 FPGA board using Verilog-HDL. As a result, the performance of the proposed method was verifed by reducing hardware resource usage and confirming that the performance was the same compared to the conventional method.

GPS 수신기에서 간섭신호에 대응하기 위한 배열 안테나기반 능동 간섭 제거 방안

정의림,원현희,조성우,안병선,Jeong, Eui-Rim,Won, Hyun-Hee,Cho, Sung-Woo,Ahn, Byoung-Sun 한국정보통신학회 2015 한국정보통신학회논문지 Vol.19 No.7

GPS (global positioning system) is a popular system that provides location information by measuring arrival time difference at the receiver between several GPS satellite signals. GPS is widely used in commercial area as well as military systems. Reliable GPS signal reception is more important in the military systems. However, since the carrier frequencies of the GPS signals are well known, the GPS receivers are vulnerable to intentional jamming attacks. To remove jammers but maintain GPS signals at the received signals, a popular technique is an adaptive beam steering method based on array antenna. Among adaptive beam steering techniques, this paper considers MVDR (minimum variance distortionless response) algorithm, and proposes a new adaptive technique that preserves the received signals at desired direction, but removes the jamming signals adaptively. The performance of the proposed method is verified through computer simulation. GPS (global positioning system)는 지구 궤도를 도는 여러 GPS 위성의 신호를 수신하여 이들 신호의 수신 시간 차이를 이용하여 자신의 절대 위치를 알아내는 시스템으로 민간 목적뿐만 아니라 군용 목적으로도 널리 사용되고 있다. 특히 군용 시스템에서는 무기 등에도 사용되기 때문에 안정적인 GPS 수신이 민간보다 더 중요하다. 하지만 GPS는 사용 주파수가 알려져 있기 때문에 나쁜 의도로 인위적인 재밍신호를 송출하여 GPS 시스템을 무력화 시킬 수 있다는 문제가 있다. 이에 재밍신호를 제거하고 GPS 신호만을 안정적으로 수신하기 위해 GPS 수신기에 다중 안테나를 설치하고 빔 널링 기술을 이용하여 재머만을 제거하는 기술이 많이 연구되어 왔다. 이러한 기술 중에서 본 논문에서는 MVDR (minimum variance distortionless response) 기술에 기반하여 새로운 적응형 빔 제어 기술을 제안한다. 제안하는 방식은 위성 방향으로의 빔은 훼손하지 않으면서 재머 방향으로는 적응적으로 널을 형성하여 재머를 효과적으로 제거한다. 제안하는 방식의 성능은 컴퓨터 모의실험을 통해 검증한다.

GPS 수신기에서 간섭신호 제거를 위한 배열 안테나 기반 다중 빔 MVDR 기법

정의림,원현희,양기정,안병선,Jeong, Eui-Rim,Won, Hyun-Hee,Yang, Gi-Jung,Ahn, Byoung-Sun 한국정보통신학회 2017 한국정보통신학회논문지 Vol.21 No.3

GPS (global positioning system)는 지구 궤도를 도는 여러 GPS 위성의 신호를 수신하여 위성 별 수신 시간 차이를 이용하여 자신의 절대 위치를 알아내는 시스템으로 민간 목적뿐만 아니라 군용 목적으로도 널리 사용되고 있다. 특히 유도무기 등에 사용되기 때문에 신뢰성 있는 GPS 수신은 군에서 훨씬 더 중요하다. 하지만 GPS 는 사용 주파수 대역이 알려져 있고 수신신호 전력이 미약하기 때문에 인위적인 재밍신호를 송출하여 쉽게 GPS 시스템을 무력화 시킬 수 있는 문제가 있다. 이러한 간섭신호에 대응하기 위한 한 가지 방법은 GPS 수신기에 다중 안테나를 설치하고 디지털 빔포밍 기술을 이용하여 GPS 신호는 훼손하지 않으면서 재머만을 제거하는 기술이다. 본 논문에서는 MVDR(minimum variance distortionless response) 기술에 기반하여 새로운 적응형 빔 제어 기술을 제안한다. 제안하는 방식은 알려져 있는 위성 방향으로의 빔을 형성하고 재머 방향으로는 적응형 알고리즘에 의해 널을 형성하여 재머를 제거한다. 제안하는 방식의 성능은 컴퓨터 모의실험을 통해 검증한다. GPS (global positioning system) is a popular system that provides location information by measuring arrival time difference at the receiver between several GPS satellite signals. GPS is widely used in commercial area as well as military systems. Reliable GPS signal reception is more important in the military applications such as guided missiles. However, since the carrier frequencies of the GPS signals are well known and the received power is extremely low, the GPS systems are vulnerable to intentional jamming attacks. To remove jammers while maintaining GPS signals at the received signals, a popular technique is an adaptive beam steering method based on array antenna. Among adaptive beam steering techniques, this paper considers MVDR (minimum variance distortionless response) algorithm, and proposes a new adaptive technique that preserves the received signals at desired directions, but removes the unknown jamming signals adaptively. The performance of the proposed method is verified through computer simulation.

The Performance Analysis of Beamforming Algorithm for Anti- Spoofing

최윤섭,이선용,박찬식,안병선,원현희,이상정 사단법인 항법시스템학회 2016 Journal of Positioning, Navigation, and Timing Vol.5 No.3

The present paper shows that beamforming algorithm such as Minimum Variance Distortionless Response (MVDR) based on array antenna signal processing can have not only anti-jamming but also anti-spoofing characteristics. A beam pattern due to the beamforming algorithm strengthens received signal power as it is formed in the incident direction of desired signal. During the process, the effect of unnecessary signals such as spoofing signals can be reduced because the beam pattern reduces received signal power in the incident directions excluding the beam pattern-directed direction. In order to analyze the anti-spoofing effect due to the beamforming algorithm, a software-based simulation environment was configured. An arbitrary error was applied between incident direction of Global Positioning System (GPS) satellite signal and steering vector direction of the beamforming algorithm to analyze the received signal power and required conditions were provided to see the antispoofing effect due to the beamforming algorithm. The used antenna was 7-element planar circular array and beam patterns were formed through the MVDR algorithm.

다채널 GPS 항재밍 장치의 설계 및 구현에 관한 연구

양기정(Kijung Yang),원현희(Hyunhee Won),안병선(Byungsun Ahn),이광석(Kwangseok Lee),오혁준(Hyukjun Oh) 한국통신학회 2017 한국통신학회 학술대회논문집 Vol.2017 No.6

초음파유도 난포채란기의 개발과 이의 검증

최민철,이효종,조성근,강태영,원현희,Choi, Min-cheol,Lee, Hyo-jong,Cho, Seong-keun,Kang, Tae-yung,Won, Hyun-hui 대한수의학회 1999 大韓獸醫學會誌 Vol.39 No.6

This study was carried out to develop a newly designed ovum pick-up(OPU) instrument for ultrasound-guided transvaginal follicular aspiration in cows. This new instrument consists of out- & inner-layer stainless pipes and a grip with a trigger(hand) switch. Some gauge types of disposable needles and tubes can be attached to this inner pipe. With this instrument, while grasping an ovary with one hand, the other hand can handle in apiration and vacuum on/off with the least assitant's help. With this instrument the mean recovery rate of bovine follicular oocytes was 45.2%. In recovered oocytes, usable oocytes(Grade I & II) were 30.4% and this rate meant 1.4 oocytes per ovary. For 30 days after initial aspiration with this instrument, some adverse effects such as adhesion, hemorrhage, hematoma and other mass formation in/with ovaries were also examined by rectal examination, ultrasonographic and endoscopic images. Adhesion was found in one ovary 1 week after aspiration, and hemorrhagic lesion was found 1-2 days and petechia were found 3-5 days after aspiration and there was no remarkable adverse effects. It was found that this instrument could be applicable and safe for ovum pick-up in cows.

동물(젖소)건강 Monitoring system 모델 개발 V. 임상학적 위해요소 분석

최민철,김종수,김곤섭,김용환,이효종,손우진,원현희 한국임상수의학회 1999 한국임상수의학회지 Vol.16 No.2

An animal health monitoring system in Gyeongnam area (near-Chinju) was studied to evaluate the environmental risk factors, physical examinations and 4 disease entities(abomasal displacement, traumatic reticulopericarditis & -peritonitis, milk fever and lameness) in 40(34 in second year)dairy herds (total 1253 dairy cattle). In feeding environments, we examined housing system, forage percentage in ration, stall types, playground, cleanness of stall. In housing system, most of herds (60%) have tie-stall types and 36 herds are open-type housing. The forage ratio of ration was less than 50% in most of herds (67%). 39 herds had their own playgrounds and the frequency of playground cleanness was irregular, Physical examinations included the T(temperature), P (pulse), R (respiration), abnormalities of superficial lymph nodes, claw examination and total CBC with blood from tail veins. T, P, R are within normal limits (T : 38.1$\pm$0.6$^{\circ}C$, P : 84.6$\pm$12.9/min., R : 24.0$\pm$7.6/min. ,respectively), the swelling of lymph nodes were shown in 13 cattle and overall claw trimming was required in 3 herds. In blood examination, 23 cattle showed leuko-cytosis and 7 cattle showed low RBC and hemoglobin level, the other cattle were within normal limits (WBC : 8.90$\pm$2.06 10$^3$/ul., RBC : 6.36$\pm$1.02 10$^{6}$ ul, Hb : 9.83$\pm$ 1.20 g/dl PCV : 27.43$\pm$5.67 %, respectively). In 4 disease entities, we found some metallic foreign bodies in men of 13 cattle, which had predisposing factors of traumatic reticulopericarditis and reticuloperitonitis, 13 abomasal displacement, 51 milk fever and lameness in 39 cattle.

교상에 의한 개의 전두동염증의 1례

최민철,김진구,김태원,김용환,신종욱,원현희,이은주 한국임상수의학회 1999 한국임상수의학회지 Vol.16 No.1

A 4-year old male Pitbull terrier dog was presented with a history of nasal discharge of left side and dyspnea for 3 days. This dog had a bitewound on the head due to dog-fighting two weeks ago. There was no abnomality except mild anemic sign on blood examination. Frontal projection of radiographs was taken. This was diagnosed as frontal sinusitis. After skin incision on frontal head, a silicone tube was inserted into the affected frontal sinus. Abscess of the frontal sinus was drainaged and irrigated with saline solution containing trypsin and cephazolin. This patient who also treated with enrofloxacin was recovered completely.

이익조정 측정모형으로서 발생액모형과 수익모형의 적합성, 검정력 비교연구

안치현 ( Chihyoun Ahn ),김미옥 ( Mi-ok Kim ),원현희 ( Hyun-hee Won ),정형록 ( Hyung-rok Jung ) 한국회계학회 2016 회계저널 Vol.25 No.1

본 연구의 목적은 Stubben(2010)의 수익모형이 우리나라 기업의 이익조정을 식별해 내는지 분석하는 것이다. 구체적으로 국내 상장기업의 수명주기별로 수익모형과 발생액모형의 모형적합성과 모형검정력을 비교하여 수익모형이 경영자의 이익조정을 식별해 낼수 있는 있는지를 확인하였다. 분석결과는 다음과 같다. 첫째, 회귀분석결과 4사분기 수익변화의 계수가 1~3사분기의 수익변화의 계수보다 10배 이상 컸다. 또한 분기수익모형이 연간수익모형보다 설명력이 더 높은 것으로 나타났다. 둘째, 시뮬레이션 결과 평균편의는 모든 모형에서 0에 근사한 값을 보였다. 표준편차는 수익모형들이 발생액모형들보다 작았다. 모형적합성 분석에 있어서 표본에 따라 다른 결과를 보였다. 모형의 검정력을 분석한 결과 수익조작은 수익모형이, 비용조작은 발생액모형의 검정력이 높은 것으로 나타났으며, 수익-비용조작에 있어서는 두 모형들이 비슷한 검정력을 보였다. 본 연구는 기존의 발생액모형과 수익모형의 시뮬레이션을 통해 기업의 수명주기에 따른 모형의 적합성과 검정력을 비교함으로써 수익모형의 유용성을 파악하는데 밑거름을 다졌다. 따라서 향후 이익조정 연구에서 발생액모형의 보완적 모형으로 수익모형을 소개하였다는데 시사점이 있다. This research studies whether Stubben(2010)’s revenue models identify earnings management in Korea firms. Prior studies related with earnings management generally use aggregate accrual models to detect earnings management, such as Jones model, modified Jones model, and performance matched modified Jones model. However, there have been controversial issues about discretional accrual as a proxy of earnings management. Accordingly, this study examines the usefulness of discretionary revenue models to detect earnings management in Korean firms. Stubben(2010) asserts that revenue, as the most important component of earnings, is a variable affected by the discretion of managers. This study specifically tests whether revenue models can detect earnings management of managers by comparing the specifications and powers between revenue models and aggregate accrual models for listed firms in Korea. As our contributions to prior studies, this study suggests that the specification and power of revenue models and aggregate accrual models should be investigated by corporate life cycle, and that either or both models should be complementarily used according to the characteristics of corporate cycle stages. Based on the previous studies(Anthony and Ramesh 1992; Koh and Kim 2012) suggesting that management environment, organizational structure, management strategy, and decision-making structure are the function of corporate life cycle, which also leads to a difference in the characteristics of accounting information. The results of our study are as follows: First, from results of regression analysis, in the revenue models, the coefficient on change in fourth-quarter revenues is over ten times higher than that of the change in revenues of the first three quarters. In addition, the adjusted R2 of quarter revenue model is higher than annual revenue model. Our results are similar to those of Stubben(2010) because this study considers the likelihood that revenues of the fourth quarter in the quarter revenue model are not cashed out and remain as accounts receivables at year-end. The Fama-Macbeth regression analysis in the extended annual revenue model reveals that most of variables are not statistically significant. This is inconsistent with Stubben(2010), where the coefficients of all variables in the extended annual revenue model are significant, except GRM_S Qi,t. It is considered that this inconsistency is due to the difference in the number of samples between Stubben(2010) and this study, and that multicollinearity among independent variables, including revenues, size, age and gross margin, affects the result. For this reason, caution needs to be taken in interpreting the extended annual revenue model for Korean firms. Second, from results of simulation, the mean bias of each model is approximate zero. This is consistent with the reasoning behind the model design, where the mean bias of each model needs to have an approximate zero because the mean of discretionary accruals(or revenues) is zero. The standard deviation of the revenue models is lower than that of the aggregate accrual models. In revenue models, the standard deviation of the revenue model is lower than that of the extended annual revenue model on average. Since a model with a lower standard deviation is more likely to detect manipulation, it is anticipated that revenue models have a higher possibility to detect manipulation than aggregate accrual models. In the specification of model analyses, specification is based on models without under- or over-reject. Revenue models are advantageous in growth firms, mature stage and stagnant stage, while aggregate accrual models are advantageous in growth stage and mature/stagnant stage. In the entire firms and growth/mature stage, both revenue models and aggregate accrual models are well specified. In addition, the power of models is analyzed based on the highest detection rate. The results show that the power of revenue models is higher for revenue manipulation, while the power of aggregate accrual models is higher for expense manipulation, and that both models have a similar power in revenue-expense manipulation. Taken together, it is found that firms with more potential to grow are more interested in increasing revenue, while firms in the mature stage are more interested in saving costs and increasing profits. This indicates that revenue models can be used as complementary models of aggregate accrual models. This study lays the groundwork for identifying the usefulness of revenue models by comparing the specification and power through a simulation of aggregate accrual models and revenue models. Therefore, this study has an implication that it introduces revenue models as the complementary models of aggregate accrual models. It is expected that the study would be a starting point for the further studies on revenue models. The limitations of this study are as follows. First, the considerably small number of samples in this study with 5,167 firm-years, compared to 70,580 firm-years in Stubben(2010), is likely to affect the statistical significance of the results. Thus, a future analysis with larger samples will enhance its comparability with Stubben(2010)’s. Second, this study can not develop a model that considers quarterly characteristics and firm characteristics. The development of a model that considers the characteristics variables with seasonality will increase the explanatory power of revenue models. Third, Stubben(2010) regards firms with accounting fraud investigated by SEC as proxies of accounting manipulation firms for analysis purpose. This study, however, can not conduct the same analysis with Stubben(2010) because the number of samples in firms subject to enforcement actions, which are proxies of actual accounting manipulation firms in Korea, is not large enough.