• Current Optics and Photonics
• /
• v.6 no.2
• /
• pp.171-182
• /
• 2022

A single-photon laser and mid-wave infrared (MWIR) common aperture optical system was designed and developed to detect and range a long-distance civil aviation aircraft. The secondary mirror of the Ritchey-Chretien (R-C) optical system was chosen as a dichroic lens to realize the design of a common aperture system for the laser and MWIR. Point spread function (PSF) ellipticity was introduced to evaluate the coupling efficiency of the laser receiving system. A small aperture stop and narrow filter were set in the secondary image plane and an afocal light path of the laser system, respectively, and the stray light suppression ability of the small aperture stop was verified by modeling and simulation. With high-precision manufacturing technology by single point diamond turning (SPDT) and a high-efficiency dichroic coating, the laser/MWIR common aperture optical system with a 𝜑300 mm aluminum alloy mirror obtained images of buildings at a distance of 5 km with great quality. A civil aviation aircraft detection experiment was conducted. The results show that the common aperture system could detect and track long-distance civil aviation aircraft effectively, and the coverage was more than 450 km (signal-to-noise ratio = 6.3). It satisfied the application requirements for earlier warning and ranging of long-range targets in the area of aviation, aerospace and ground detection systems.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.257-257
• /
• 2022

댐 건설은 홍수 및 가뭄에 대응하기 위한 구조적 방법으로써 우리나라와 같이 지표수에 의존적인 지역에서는 가용 수자원을 확보하기 위한 확실한 수단으로 활용되어왔다. 신규 댐의 건설은 대상 하천의 수리학적 특성에 큰 변화를 야기할 수 있으며, 댐의 안정성 및 하천의 하도보호를 위해 댐 주변의 수리적 특성의 변화에 대해서도 사전에 인지하여 설계 시 반영할 필요가 있다. 수공구조물 신설에 따라 변화되는 수리학적 특성을 분석하는 방법으로는 그 수단에 따라 상사법칙을 적용한 수리모형실험과 수치기법을 활용한 수치모형실험으로 나눌 수 있다. 본 연구에서는 수리모형실험을 통한 실험적 방법을 이용하여 댐 상하류 구간의 수리학적 특성을 분석하였다. 해당 실험은 한국농어촌공사 농어촌연구원의 대형수리모형실험시설에서 수행되었다. 적용대상 댐의 제원은 높이 약 70m, 길이 약 230m이며, 폭 55m의 여수로를 포함하는 구조로 설정하였다. 수리모형은 Froude 상사법칙을 적용하여 1/30 규모로 축소하였으며, 콘크리트 및 아크릴 재료를 이용하여 제작되었다. 댐 모형이 설치되는 하천구간은 댐 구조물을 포함하여 실규모를 기준으로 흐름방향으로 약 800m, 하폭방향으로 약 450m의 범위를 포함하도록 설계되었으며, 하류구간에 사행하천이 존재하는 것이 특징이다. 본 실험에서 유량은 총 12개의 펌프를 이용하여 공급되었으며, 최대 4cms에 해당하는 유량공급이 가능하도록 설계하였다. 공급유량은 정교한 절차에 의해 보정된 전자식 유량계를 통해 통제되었으며, 사용된 유량계의 허용오차는 약 0.5% 수준인 것으로 나타났다. 수위 측정은 오차범위 0.05mm 수준의 초음파 수위측정기를 이용하였으며, 유속측정은 약 0.5cm/s의 정확도를 지닌 3차원 전자기 유속계를 이용한 접촉식 측정과 흐름구조 가시화를 위한 비접촉식 입자추적기법을 병행하였다. 실험조건은 실규모 기준으로 방류량 3,000~5,000cms에 대해 수행하였으며, 각 방류량별 댐 상하류의 흐름패턴에 대해 정량적으로 분석하였다.

• Journal of Technologic Dentistry
• /
• v.45 no.4
• /
• pp.87-94
• /
• 2023

Purpose: This study aimed to observed changes in the shape of dental barrels based on application time. Machinability measures the angle of alloy specimens. Polishing performance measures the surface roughness of alloy specimens. Methods: The dental barrel polishing equipment used in this study was a Snow Barrel (DK Mungyo). Three types of cobalt-chromium alloys for partial dentures were used as specimens (BC CAST R [BP]; Bukwang, Vera PDI [VP]; Aalbadent, and GM 800+ [GP]; Dentaurum). Specimens were prepared in the form of plates (10 mmx10 mmx2 mm). Dental barrel polishing was performed at 450 rpm for 60 minutes with intervals of 5 minutes. The processing angle was measured using a microscope (SZ61; Olympus). Results: For the angle measurement, the VPC specimen was measured at 78.64°, 36.00° for the VP60 specimen, 79.57° for the BP control (BPC) specimen, 28.07° for the BP60 specimen, 75.01° for the GPC specimen, and 39.92° for the GP60 specimen. For the surface roughness measurements, the average surface roughness of the VPC and VP15 specimens were 1.09 ㎛ and 0.26 ㎛, respectively. The average surface roughness of the BPC and BP20 specimens were 1.77 ㎛ and 0.29 ㎛, respectively. The average surface roughness of the GPC and GP15 specimens were 1.08 ㎛ and 0.27 ㎛. Conclusion: The results were excellent after about 20 minutes of dental barrel polishing conditions presented in this study.

• Korean Journal of Radiology
• /
• v.25 no.9
• /
• pp.833-842
• /
• 2024

Objective: To assess the effect of a new lung enhancement filter combined with deep learning image reconstruction (DLIR) algorithm on image quality and ground-glass nodule (GGN) sharpness compared to hybrid iterative reconstruction or DLIR alone. Materials and Methods: Five artificial spherical GGNs with various densities (-250, -350, -450, -550, and -630 Hounsfield units) and 10 mm in diameter were placed in a thorax anthropomorphic phantom. Four scans at four different radiation dose levels were performed using a 256-slice CT (Revolution Apex CT, GE Healthcare). Each scan was reconstructed using three different reconstruction algorithms: adaptive statistical iterative reconstruction-V at a level of 50% (AR50), Truefidelity (TF), which is a DLIR method, and TF with a lung enhancement filter (TF + Lu). Thus, 12 sets of reconstructed images were obtained and analyzed. Image noise, signal-to-noise ratio, and contrast-to-noise ratio were compared among the three reconstruction algorithms. Nodule sharpness was compared among the three reconstruction algorithms using the full-width at half-maximum value. Furthermore, subjective image quality analysis was performed. Results: AR50 demonstrated the highest level of noise, which was decreased by using TF + Lu and TF alone (P = 0.001). TF + Lu significantly improved nodule sharpness at all radiation doses compared to TF alone (P = 0.001). The nodule sharpness of TF + Lu was similar to that of AR50. Using TF alone resulted in the lowest nodule sharpness. Conclusion: Adding a lung enhancement filter to DLIR (TF + Lu) significantly improved the nodule sharpness compared to DLIR alone (TF). TF + Lu can be an effective reconstruction technique to enhance image quality and GGN evaluation in ultralow-dose chest CT scans.

• Mass Spectrometry Letters
• /
• v.5 no.2
• /
• pp.42-48
• /
• 2014

A specific and sensitive liquid chromatography-electrospray ionization tandem mass spectrometry method (LC-ESI-MS/MS) was developed and validated for the simultaneous quantification of porphyrins (coproporphyrin, pentacarboxylporphyrin, hexacarboxylporphyrin, heptacarboxylporphyrin, and uroporphyrin) in human plasma and urine. Acidified plasma samples and urine samples were prepared by using liquid-liquid extraction using ethyl acetate and protein precipitation with acetonitrile, respectively. The separation was achieved onto a Synergi Fusion RP column ($150mm{\times}2.0mm$, $4{\mu}m$) with a gradient elution of mobile phase A (0.1% formic acid in 2 mmol/L ammonium acetate, v/v) and mobile phase B (20% methanol in acetonitrile, v/v) at a flow rate of $450{\mu}L$/min. Porphyrins and the internal standard (IS), coproporphyrin I-$^{15}N_4$, were detected by a tandem mass spectrometer equipped with an electrospray ion source operating in positive ion mode. Multiple reaction monitoring (MRM) transitions of the protonated precursor ions and the related product ions were optimized to increase selectivity and sensitivity. The proposed method was validated by assessing selectivity, linearity, limit of quantification (LOQ), precision, accuracy, recovery, and stability. The calibration curves were obtained in the range of 0.1-100 nmol/L and the LOQs were estimated as 0.1 nmol/L for all porphyrins. Results obtained from the validation study of porphyrins showed good accuracy, precision, recovery, and stability. Finally, the proposed method was successfully applied to clinical studies on the autism spectrum disorder (ASD) diagnosis of 203 Korean children.

• Journal of the Korean Society of Radiology
• /
• v.12 no.4
• /
• pp.443-450
• /
• 2018

The Geant 4 simulated the linear accelerator (VARIAN CLINAC) based on the previously implemented BEAMnrC data, using the head structure of the linear accelerator. In the 10 MV photon flux, Geant4 was compared with the measured value of the percentage of the deep dose and the lateral dose of the water phantom. In order to apply the dose calculation to the body part, the actual patient's lung area was scanned at 5 mm intervals. Geant4 dose distributions were obtained by irradiating 10 MV photons at the irradiation field ($5{\times}5cm^2$) and SAD 100 cm of the water phantom. This result is difficult to measure the dose absorbed in the actual lung of the patient so the doses by the treatment planning system were compared. The deep dose curve measured by water phantom and the deep dose curve calculated by Geant4 were well within ${\pm}3%$ of most depths except the build-up area. However, at the 5 cm and 20 cm sites, 2.95% and 2.87% were somewhat higher in the calculation of the dose using Geant4. These two points were confirmed by the geometry file of Genat4, and it was found that the dose was increased because thoracic spine and sternum were located. In cone beam CT, the dose distribution error of the lungs was similar within 3%. Therefore, if the contour map of the dose can be directly expressed in the DICOM file when calculating the dose using Geant4, the clinical application of Geant4 will be used variously.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.5
• /
• pp.443-450
• /
• 2020

This paper reports a design improvement study to solve the stoppage phenomenon caused by the launch-support device applied to K105A1. The K105A1 is a weapon system equipped with an old 105 mm towed howitzer in a wheeled vehicle, which provides superior maneuverability compared to track equipment. The launch support device serves to withstand fire impact and load. In this way, this device is fixed firmly to the ground in preparation for the shooting mission and is responsible for the critical performance, such as fixing the position of the vehicle. On the other hand, during the field test, a temporary stoppage of the launch support occurred, which caused a problem of not being fixed to the ground. To solve this problem, the cause of failure was analyzed by a replay test and parts inspection. In addition, the operating concept, method, and design were analyzed to derive the cause and solve the problem by changing the parts design. Finally, the performance and firing missions were performed normally by applying the changed design to K105A1. The performance stability and reliability of the launch support device were confirmed, which are expected to be of great assistance in the development of military equipment in the future.

• The Korean Journal of Malacology
• /
• v.28 no.4
• /
• pp.305-312
• /
• 2012

Manila clam, Ruditapes philippinarum (SL; $32.74{\pm}2.18mm$, TW; $8.29{\pm}1.41g$, N; 450) were exposed to various concentrations of naphthalene for 20 weeks. Exposure concentrations of naphthalene established control, solvent control (ethanol), 30, 60, 90 and $120{\mu}g$ Nap $L^{-1}$ following results of 96h acute exposure. After exposure during 20 weeks, survival rate of the manila clam was lowed in 60, 90 and $120{\mu}g$ Nap $L^{-1}$ exposure group compared control group. Also, sex ratio of male was higher in $60{\mu}g$ Nap $L^{-1}$ exposure group (${\chi}^2=5.492$, P < 0.05) but lowed $90{\mu}g$ Nap $L^{-1}$ exposure group (${\chi}^2=4.214$, P < 0.05) and $120{\mu}g$ Nap $L^{-1}$ exposure group (${\chi}^2=30.118$, P < 0.05). Gonad development was delayed in female (> $60{\mu}g$ Nap $L^{-1}$) and male (> $30{\mu}g$ Nap $L^{-1}$). Intersex was 16.28% in female, 1.68% in male. In this result, naphthalene caused survival decrease, imbalance of sex ratio, delay of gonad development of the manila clam. Also, chronic exposure to naphthalene suggested abnormal effects in reproduction of the manila clam.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.318-318
• /
• 2010

전기로를 이용하여 셀렌화한 $CuInSe_2$ (CIS)박막에 대해 연구한 결과를 발표하고자 한다. 화석연료의 과도한 사용으로 지구온난화의 환경문제가 대두되면서 영구적이고 무상의 태양에너지 이용에 대한 필요성이 점차 높아지고 있다. 빛에너지를 전기에너지로 변화시키기 위한 태양전지는 재료에 따라 다양하게 개발되고 있으며 그 중 가장 주목을 받고 있는 것 중의 하나가 $CuInSe_2$을 흡수층으로 하는 CIS 박막 태양전지이다. CIS 박막은 태양전지의 흡수층으로 사용되는데 직접천이형 밴드구조를 가지고 있고, 약 $10^5\;cm^{-1}$의 높은 광흡수계수를 가지고 있어 태양전지의 흡수층으로 적합한 물질로 각광받고 있다. 에너지 밴드갭이 1eV로 실리콘과 유사한 밴드갬을 가지고 있으나 이는 Ga, Al을 In 대신 치환함으로 조절할 할 수 있다. 무엇보다도 유리와 같은 저가의 기판위에 스퍼터와 같은 장치로 대면적 CIS 태양전지를 만들수 있다는 것이 산업적인면에서의 장점으로 알려져 있다. 본 연구에서는 $50mm{\times}50mm$ 넓이의 sodalime 유리판을 기판으로 하여 CIS 박막을 제조하고 연구하였다. 스퍼터를 이용하여 유리기판 위에 Mo (Molybdenum) 을 증착하고 그 위에 Cu-In막을 증착하였다. Cu-In/Mo/유리기판 시료는 전기로에 도입되어 셀렌화 처리 하였다. 전기로는 $10^{-1}$ Torr 정도의 진공을 수분간 유지하여 반응할 수 있는 공기(산소)를 제거하였다. 진공 혹은 5N의 고순도 질소를 흘려주며 열을 가하여 셀렌화를 하였다. 전기로에는 1g의 셀레늄(Se)이 Cu-In/Mo/유리기판 시료와 함께 도입되었다. Se이 Cu-In 막과 높은 반응성을 갖도록 Se과 Cu-In 시료는 그라파이드 상자에 함께 넣었고, 그라파이트 상자는 전기로에 넣어 셀렌화하였다. 셀렌화 온도는 $400^{\circ}C{\sim}500^{\circ}C$까지 변화시켜 가며 CIS 박막을 제조하였으며 그 물성도 조사하였다. 물성 조사는 사진, 현미경, SEM, EDX, XRD, Hall effects를 이용하였다. 셀렌화 온도가 $450^{\circ}C$ 이상에서는 CIS 박막의 흡착성이 낮아 CIS 박막이 Mo 표면에서 떨어짐을 알 수 있었다. 셀렌화 후 박막에 함유된 Se은 48%~49% 정도있었다. 제조된 CIS 박막시료를 SEM으로 확인한 결과 생성된 CIS/Mo 사이에 계면층이 생겼있음 알 수 있었다. 이러한 계면층은 $MoSe^2$층으로 사료되고, 셀렌화 온도가 높으면 계면층의 두께도 증가되는 경향을 보였다. 셀렌화 온도가 높아질수록 많은 양의 산소가 CIS 박막에 들어가는 것도 알 수 있었다. 학술회의에서 보다 깊은 조사결과를 발표하고자 한다.

• Parasites, Hosts and Diseases
• /
• v.36 no.2
• /
• pp.81-90
• /
• 1998

The present study was performed to observe the infection status of several kind of animals with indigenous Gnnthostomn in Korea, and morphological characteristics of gnathostome larvae detected from pit-viper, Askistronon breuiccudus, for the species bullfrogs. several kinds of snakes, j.e., 55 Elnphe rufodorsata, 2 Dinodon rufozonatum rufzonatum. 62 Rhnbdophis tisrinus tigrinus and 87 Askistronon app., and 438 cats were examined. A total of 21 larval gnathostomes was detected from 12 pit-vipers, A. breuicnudus. They were 2.233 x 0.343 mm in average size and covered with about 210 transverse rows of minute cuticular spines. Their characteristic head bulbs were provided with 4 rows of hooklets of which average numbers in each row were 36.8, 39.0, 41.7 and 44.3. posteriorly. In the cross sections of midgut level, the intestinal wall consisted of a single layer of 19-25 elongate epithelial cells with a single nucleus. SEM observation of the larvae revealed unique features of head bulb , cuticular spines on transverse striations and a cervical papilla. On the basis of above morphological characteristics, they were identified as the advanced third-stage larvae of Gnothostomo hispinum. It was first confirmed that the pit-viper. ABkistronon breuicaunus is the snake intermediate host of G. hispidun.