• 한국재료학회지
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• 제22권10호
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• pp.539-544
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• 2012

We have grown AlN nanorods and AlN films using plasma-assisted molecular beam epitaxy by changing the Al source flux. Plasma-assisted molecular beam epitaxy of AlN was performed on c-plane $Al_2O_3$ substrates with different levels of aluminum (Al) flux but with the same nitrogen flux. Growth behavior of AlN was strongly affected by Al flux, as determined by in-situ reflection high energy electron diffraction. Prior to the growth, nitridation of the $Al_2O_3$ substrate was performed and a two-dimensionally grown AlN layer was formed by the nitridation process, in which the epitaxial relationship was determined to be [11-20]AlN//[10-10]$Al_2O_3$, and [10-10]AlN//[11-20]$Al_2O_3$. In the growth of AlN films after nitridation, vertically aligned nanorod-structured AlN was grown with a growth rate of $1.6{\mu}m/h$, in which the growth direction was <0001>, for low Al flux. However, with high Al flux, Al droplets with diameters of about $8{\mu}m$ were found, which implies an Al-rich growth environment. With moderate Al flux conditions, epitaxial AlN films were grown. Growth was maintained in two-dimensional or three-dimensional growth mode depending on the Al flux during the growth; however, final growth occurred in three-dimensional growth mode. A lowest root mean square roughness of 0.6 nm (for $2{\mu}m{\times}2{\mu}m$ area) was obtained, which indicates a very flat surface.

• 비파괴검사학회지
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• 제27권6호
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• pp.531-540
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• 2007

While determination of the solid propellant burning rates by ultrasound, it has been reported that the frequent data scatters were caused by two major factors; 1) variation in the acoustical properties, and 2) non-linear burning of a solid propellant sample under investigation. This work is carried out for the purpose of investigating the effect of non-linear burning of solid propellant samples. Specifically, we propose an ultrasonic measurement model that can predict the reflections from solid propellant surfaces with non-linear burning by the combination of two ingredients; 1) a pulse-echo ultrasonic measurement model for a planar, circular reflector imbedded in the second medium in an immersion set-up, and 2) an efficient model of non-linear burning surfaces with a number of small, planar circles. Then, we demonstrate the capability of the proposed measurement model by simulation of the surface echo signals from four different burning surfaces that have been generated by the combination of two factors; the base shape (flat or paraboloidal) and the surface roughness (perfectly smooth or randomly rough). From the simulation presented here, we can confirm the fact that the non-linear burning of the propellant can cause the waveform change of the burning surface echo and the corresponding spectrum variation.

• 인터넷정보학회논문지
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• 제4권5호
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• pp.1-9
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• 2003

본 논문에서는 CDMA 시스템에서 적응 변조 및 부호화 (AMC) 기법의 성능을 향상시키기 위한 방안으로서 기지국과 단말기 간에 개루프 및 폐루프 전송 다이버시티를 적용하였다. 이는 전송 다이버시티를 적용하여 수신 단의 신호 대 잡음비 (SNR)를 개선함으로써, 보다 높은 전송률을 지원하는 변조 및 부호화 레벨이 선택될 확률을 증가시키고 이에 따른 평균 전송률의 이득을 얻고자 하는 것이다. 개루프 전송 다이버시티로는 시공간 블록 부호화 기반 전송 다이버시티 (STTD) 기법을, 폐루프 전송 다이버시티로는 선택적 전송 다이버시티 (STD) 기법을 적용하였다. 모의 실험 결과, AMC 기법과 전송 다이버시티를 결합함으로써 기존 시스템에 비하여 향상된 전송률을 얻을 수 있었다. 단일 경로 레일리 페이딩 채널 환경에서 두 개의 전송 안테나를 사용한 AMC-STTD는 9dB신호 대 잡음비에 대하여 기존의 AMC 기법보다 약 250kbps의 전송률 이득을 보였다. 또한 두 개의 전송 안테나를 사용한 AMC-STD의 경우는 역시 9dB 신호 대 잡음비에서 약 420kbps의 전송률 이득이 얻어짐을 확인하였다.

• 대한조선학회논문집
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• 제58권5호
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• pp.303-313
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• 2021

Recently, quality control of the Liquefied Natural Gas Carrier (LNGC) cargo hold and block-erection interference areas using 3D scanners have been performed, focusing on large shipyards and the international association of classification societies. In this study, as a part of the research on LNGC cargo hold quality management advancement, a study on deep-learning-based scaffolding system 3D point cloud object detection and post-processing were conducted using a LNGC cargo hold 3D point cloud. The scaffolding system point cloud object detection is based on the PointNet deep learning architecture that detects objects using point clouds, achieving 70% prediction accuracy. In addition, the possibility of improving the accuracy of object detection through parameter adjustment is confirmed, and the standard of Intersection over Union (IoU), an index for determining whether the object is the same, is achieved. To avoid the manual post-processing work, the object detection architecture allows automatic task performance and can achieve stable prediction accuracy through supplementation and improvement of learning data. In the future, an improved study will be conducted on not only the flat surface of the LNGC cargo hold but also complex systems such as curved surfaces, and the results are expected to be applicable in process progress automation rate monitoring and ship quality control.

• Journal of Korean Neurosurgical Society
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• 제62권5호
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• pp.526-535
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• 2019

Objective : While the risk of aneurysmal rebleeding induced by catheter cerebral angiography is a serious concern and can delay angiography for a few hours after a subarachnoid hemorrhage (SAH), current angiographic technology and techniques have been much improved. Therefore, this study investigated the risk of aneurysmal rebleeding when using a recent angiographic technique immediately after SAH. Methods : Patients with acute SAH underwent immediate catheter angiography on admission. A four-vessel examination was conducted using a biplane digital subtraction angiography (DSA) system that applied a low injection rate and small volume of a diluted contrast, along with appropriate control of hypertension. Intra-angiographic aneurysmal rebleeding was diagnosed in cases of extravasation of the contrast medium during angiography or increased intracranial bleeding evident in flat-panel detector computed tomography scans. Results : In-hospital recurrent hemorrhages before definitive treatment to obliterate the ruptured aneurysm occurred in 11 of 266 patients (4.1%). Following a univariate analysis, a multivariate analysis using a logistic regression analysis revealed that modified Fisher grade 4 was a statistically significant risk factor for an in-hospital recurrent hemorrhage (p=0.032). Cerebral angiography after SAH was performed on 88 patients ${\leq}3$ hours, 74 patients between 3-6 hours, and 104 patients >6 hours. None of the time intervals showed any cases of intra-angiographic rebleeding. Moreover, even though the DSA ${\leq}3$ hours group included more patients with a poor clinical grade and modified Fisher grade 4, no case of aneurysmal rebleeding occurred during erebral angiography. Conclusion : Despite the high risk of aneurysmal rebleeding within a few hours after SAH, emergency cerebral angiography after SAH can be acceptable without increasing the risk of intra-angiographic rebleeding when using current angiographic techniques and equipment.

• 한국응용과학기술학회지
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• 제36권2호
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• pp.448-455
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• 2019

본 연구는 오르막 퍼팅 시 좌, 우 경사에 따른 볼의 움직임이 어떻게 변화되는지에 대해 알아보는 것을 목적으로 한다. 본 연구를 위해 한국프로골프협회에서 15년 이상의 골프경기 경험이 있는 피험자들이 참여하였고, 본인들의 퍼터를 이용하여 실제 그린과 유사한 환경에서 퍼팅 동작을 수행하였다. 비디오 카메라를 이용하여 피험자들의 오르막 그린 경사에 따른 퍼팅 동작을 수집 후 동작분석을 실시하였으며, 통계적 유의수준을 a=.05로 설정하였다. 연구결과로 좌, 우 경사별 오르막 퍼팅에서 볼의 위치가 왼쪽에서 오른쪽으로 위치 할 때 볼 움직임의 속도와 각속도가 증가하는 것이 확인되었으며, 여러 경사도 중 성공률을 높여야 하는 오르막 퍼팅에서 경사에 따른 어드레스 볼 위치를 변화할 때, 임팩트 시 클럽 페이스와 볼 움직임이 어떻게 변화하는지를 검증하고, 현장적용 측면에 도움을 주는 과학적 자료를 제시하고자 본 연구를 진행하였다.

• 한국의상디자인학회지
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• 제21권2호
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• pp.95-108
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• 2019

This study aims to determine the characteristics of new senior women's torso shapes. The data was collected from the 7th Size Korea, which analyzed 412 women between the ages of 55-69. A factor analysis was performed based on 20 indices, including eight based on circumference, eight based on height and length measurements, and four based on torso flattening. The results of the factor analysis suggest five main factors: torso silhouette, longitudinal size of the body, torso flattening rate, abdominal shape, and posterior longitudinal size. The results of the cluster analysis suggest three overall types: Type 1 is the inverted triangular obese shape which is characterized by large breasts, small buttocks, a short height, and a forward-bending posture; Type 2 is the rectangular, slim shape which is characterized by a forward neck and a flat front and back of the torso, and is the most slender among the three types; Type 3 is the large rectangular, overall obese shape, which is characterized by a round shape with large breasts, waist, and buttocks, and a forward-bending posture with a protruding back, and this is the most obese type. According to the results of the cross-tabulation, women aged 55-59 showed no trend in body shape; women aged 60-64 showed an increases in the inverted triangular obese shape and the large rectangular, overall obese shape; women aged 65-69 showed an increase in the large rectangular, overall obese shape and a decrease in the rectangular slim shape. In summary, new senior women showed body shape characteristics of being short, more obese having, a bent over posture. As they grew older, the curves disappeared, and the body becomes rounder. The study found that variation in body shape exists among new senior women in the aged society.

• 한국균학회지
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• 제47권2호
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• pp.143-152
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• 2019

본 실험은 '산백향'과 '장안1호'의 단포자 간 교잡에 의해 새로운 품종을 만들었으며 그 이름을 '산장향'이라 명명하였다. '산장향'의 주요 형태적 특성은 갓이 평반구형이며, 갓의 직경은 67.1 mm, 갓두께는 16.9 mm이었다. 주름살 측면 모양은 부정형이며 주름의 밀도는 조밀하고 주름살의 폭은 좁다. 인편은 흰색 또는 옅은 갈색으로 갓 전체에 분포하였다. 대조품종인 '산백향'보다 대의 길이가 길고, 갓 색깔은 갈색계열이나 적색이 진하였다. 대의 표면에는 털이 있고 대와 같은 크림색이었다. 버섯은 산발 발생으로 솎아주기 작업을 적게 할 수 있었다. 자실체의 발이온도는 평균 $15-19^{\circ}C$으로 중온성이었다. '산장향'의 발생시기는 봄, 가을 이었다. 자실체 발생은 3차까지 진행하였고, 1차(89%), 2차(4%) 및 3차(7%)의 발생비율을 보였다.

• 대한족부족관절학회지
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• 제22권3호
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• pp.111-115
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• 2018

Purpose: Ingrown toenails are a common disease in the adolescent period and the treatments could be more conservative for this early stage of the disease. This study is a case series on the results of a gutter splint for an adolescent ingrown toe nail as a simple, comfortable treatment method. Materials and Methods: From 2011 to 2018, 22 patients (mean age, 12.2 years; range, 8~15 years) with ingrown toenails were treated with a gutter splint. There were 16 boys and 6 girls with 7 patients on both great toes, and additional 4 both corners of a nail, giving a total of 33 splints. Flat, plastic straws and glue or suture were used to protect the nail corners under local anesthesia. The medical records were reviewed retrospectively and phone calls were made to obtain the long-term results. Results: Fifteen splints were fixed with a suture and the other 18 splints were fixed with glue. There were 9 cases of recurrence out of 33 gutter splints, 8 out of 15 sutured splints and 1 out of 18 glued splints (p=0.010). There was no gender (p=0.383) or age (p=0.305) difference in the number of recurrences. Conclusion: For growing people, ingrown nails can be cured easily by conservative treatment for a transiently shortened or broken toenail. The glued gutter splint had a reasonable success rate as a first line treatment.

• 대한방사선기술학회지:방사선기술과학
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• 제45권2호
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• pp.127-134
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• 2022

In order to overcome the image quality limitations of the conventional C-arm, a flat panel detector (FPD) is used to enhance spatial resolution, detective quantum efficiency, frame rate, and dynamic range. Three-dimensional (3D) visualized information can be obtained from C-arm computed tomography (CT) equipped with an FPD, which can reduce patient discomfort and provide various medical information to health care providers by conducting procedures in the interventional procedure room without moving the patient to the CT scan room. Unlike a conventional C-arm device, a C-arm CT requires different basic safety and essential performance evaluation criteria; therefore, in this study, basic safety and essential performance evaluation criteria to protect patients, medical staff, and radiologists were derived based on International Electrotechnical Commission (IEC) standards, the Ministry of Food and Drug Safety (MFDS) standards in Korea, and the rules on the installation and operation of special medical equipment in Korea. As a result of the study, six basic safety evaluation criteria related to electrical and mechanical radiation safety (leakage current, collision protection, emergency stopping device, overheating, recovery management, and ingress of water or particulate matter into medical electrical (ME) equipment and ME systems: footswitches) and 14 essential performance evaluation criteria (accuracy of tube voltage, accuracy of tube current, accuracy of loading time, accuracy of current time product, reproducibility of radiation output, linearity and consistency in radiography, half layer value in X-ray equipment, focal size and collimator, relationship between X-ray field and image reception area, consistency of light irradiation versus X-ray irradiation, performance of the mechanical device, focal spot to skin distance accuracy, image quality evaluation, and technical characteristic of cone-beam computed tomography) were selected for a total of 20 criteria.