• Title/Summary/Keyword: Resonance

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PSNR Appraisal of MRI Image (MRI 영상의 PSNR 평가)

  • Kang, Kwang-Soo;Lee, Jun-Haeng
    • Journal of the Korean Society of Radiology
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    • v.3 no.4
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    • pp.13-21
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    • 2009
  • The Magnetic Resonance Imaging (MRI) systems consist of various parameters. Among them, the image quality can be arguably the most important part of the systems. As the other components in MRI systems have been developed and evolved, the MRI image quality has been advanced remarkably. And, the radiation imaging system is being converted from the Film to the digital method, which drives the computerization of many hospitals. The management of the tremendous radiation images becomes more critical. The data compression is used to store such large data in a network server. When the image files are compressed, the image quality degrades comparing to its original images. Even slight quality degradation of a medical image could cause an erroneous diagnosis, so the images must be handled carefully. This thesis studied the image assessment methods of comparing the quality of the compressed image to its original, and the quality of the original and the displayed images of the MRI systems via PSNR with actual medical images used in hospitals. As a result, no noticeable quality degradation was found comparing the compressed images with various digital compression methods and the original images. However, it was a different story comparing the original images and the displayed images on MRI monitors. Some noise or image distortion was visible using any regular CRT or LCD monitors were used while the special monitors designed for the MRI imaging and medical images displayed high definition images.

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Successful Endoscopic Treatment of Hepatic Duct Confluence Injury after Blunt Abdominal Trauma: Case Report

  • Park, Chan Ik;Park, Sung Jin;Lee, Sang Bong;Yeo, Kwang Hee;Choi, Seon Uoo;Kim, Seon Hee;Kim, Jae Hun;Baek, Dong Hoon
    • Journal of Trauma and Injury
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    • v.29 no.3
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    • pp.93-97
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    • 2016
  • Hepatic duct confluence injury, which is developed by blunt abdominal trauma, is rare. Conventionally, bile duct injury was treated by surgical intervention. In recent decades, however, there had been an increase in radiologic or endoscopic intervention to treat bile duct injury. In a hemodynamically stable patient, endoscopic intervention is considered as the first-line treatment for bile duct injury. A 40 year-old man was transferred to the emergency department of ${\bigcirc}{\bigcirc}$ trauma center after multiple blunt injuries. Contrast-enhanced abdominal computed tomography performed in another hospital showed a liver laceration with active arterial bleeding, fracture of the sacrum and left inferior pubic ramus, and intraperitoneal bladder rupture. The patient presented with hemorrhagic shock because of intra-peritoneal hemorrhage. After resuscitation, angiographic intervention was performed. After angiographic embolization of the liver laceration, emergency laparotomy was performed to repair the bladder injury. However, there was no evidence of bile duct injury on initial laparotomy. On post-trauma day (PTD) 4, the color of intra-abdominal drainage of the patient changed to a greenish hue; bile leakage was revealed on magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography (ERCP). Bile leakage was detected near the hepatic duct confluence; therefore, a biliary stent was placed into the left hepatic duct. On PTD 37, contrast leakage was still detected but both hepatic ducts were delineated on the second ERCP. Stents were placed into the right and left hepatic ducts. On PTD 71, a third ERCP revealed no contrast leakage; therefore, all stents were removed after 2 weeks (PTD 85). ERCP and biliary stenting could be effective treatment options for hemodynamically stable patients after blunt trauma.

Evaluation of Effective Working Days in a Harbor Considering Harbor Resonance and Moored Ship Motion (항만공진주기와 선박동요량을 고려한 항만가동율 산정)

  • Kwak, Moonsu;Moon, Yongho
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.1
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    • pp.14-24
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    • 2015
  • This study proposed an estimation method of allowable wave height for loading and unloading of the ship and evaluation of effective working days considering moored ship motion that is affected by sip sizes, mooring conditions, wave periods and directions. The method was examined validity by comparison with wave field data at pier $8^{th}$ in Pohang New Harbor. The wave field data obtained with wave height of 0.10~0.75 m and wave period of 7~13 s in ship sizes of 800~35,000 ton when a downtimes have occurred. On the other hand, the results of allowable wave height for loading and unloading of the ship in this method have obtained with wave heights of 0.19~0.50 m and wave periods of 8~12 s for ship sizes of 5,000, 10,000 and 30,000 ton. Thus this method well reproduced the field data respond to various a ship sizes and wave periods. And the results of this in Korea are didn't respond to various the ship sizes and wave periods, and we h method tended to decrease in 16~62 percent when have considered long wave, and it is decreased in 0~46 percent when didn't consider long wave than design standards in case of the ship sizes of 5,000~30,000 ton, wave period of 12 s and wave angle of $75^{\circ}$. The allowable wave heights for loading and unloading of the ship proposed by design standards in Korea have found that overestimated on smaller than 10,000 ton. On the other hand, the rate of effective working days considering ship motion at pier $8^{th}$ in Pohang New Harbor reduced in 6.5 percent when compare with the results without considering ship motion.

Low Frequency Characteristic of Seoul Subway Noise (서울지하철의 저주파소음 특성)

  • Jung, Sung-Soo;Shin, Su-Hyun;Kim, Ho-Chul;Lee, Woo-Seop
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.11
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    • pp.1193-1197
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    • 2005
  • The low frequency noise below 200 Hz, including inaudible infra-sound, is known to affect human physiology ; circulation, respiration, nerve, endocrine, etc. Legislation has been introduced in several countries regarding evaluation guideline and measurement method of low frequency noise. In this work, low frequency characteristics of the Seoul subway transportation system was investigated in terms of the noise level and spectrum in the interior of running passenger car and the subway station. The interior sound pressure level of the passenger car was between 60 and 105 dB in the frequency range of $1{\sim}200\;Hz$ and varied with car speed. The marked sound pressure level peak at 8 Hz, infra-sound, observed for the most of Lines is shown to correspond to the resonance frequency of passenger car. The level of station platform noise was lower than the interior noise of running car because of the lower speed at arriving/departure. The results indicated that the interior noise level of running passenger car was inside the oppressive feeling region, proposed by Ochiai, in the frequency range of $20{\sim}80\;Hz$ which makes a little concern.

Isolation and Identification of Phenolic Compounds from the Root Bark of Morus alba L. (상백피(Morus alba root barks)로부터 페놀화합물의 분리 및 동정)

  • Jung, Jae-Woo;Park, Ji-Hae;Seo, Kyeong-Hwa;Baek, Yoon-Su;Oh, Eun-Ji;Lee, Dae-Young;Lim, Dong-Wook;Han, Daeseok;Baek, Nam-In
    • Journal of Applied Biological Chemistry
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    • v.58 no.2
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    • pp.153-155
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    • 2015
  • The root barks of Morus alba L. were extracted with 80% aqueous MeOH, and the concentrated extract was partitioned with EtOAc, n-BuOH, and $H_2O$ fractions. The repeated silica gel, octadecyl silica gel, and Sephadex LH-20 column chromatographies of the EtOAc and n-BuOH fractions led to isolation of four phenolic compounds. The chemical structures of the compounds were determined as norartocarpanone (1), 2',4',7-trihydroxy-(2S)-flavanone (2), methyl ${\beta}$-resorcylate (3), and (Z)-oxyresveratrol-4-O-${\beta}$-$\small{D}$-glucopyranoside (4). Compound 4 was isolated for the first time from the root barks of M. alba L.

Evaluation of Site-specific Seismic Response Characteristics at Town Fortress Areas Damaged by Historical Earthquakes (역사 지진 피해 발생 읍성 지역에 대한 부지 고유의 지진 응답 특성 평가)

  • Sun, Chang-Guk;Chung, Choong-Ki;Kim, Dong-Soo;Kim, Jae-Kwan
    • The Journal of Engineering Geology
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    • v.17 no.1 s.50
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    • pp.1-13
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    • 2007
  • In order to evaluate the local site effects at two town fortress areas in Korea where stone parapets were col-lapsed by historical earthquakes, site characteristics were assessed using site investigations such as borehole drillings and seismic tests. Equivalent-linear site response analyses were conducted based on the shear ways velocity ($V_s$) profiles and geotechnical characteristics determined from site investigations. The study sites are categorized as site classes C and B according to the mean $V_s$ to 30 m ranging from 500 to 850 m/s, and their site periods are distributed in the short period range of 0.06 to 0.16 sec, which contains the natural period of fortress wall and stone parapet. From the results of site response analyses in the study areas, for site class C indicating most of site conditions, contrary to site class B, the short-period (0.1-0.5 sec) and mid-period (0.4-2.0 sec) site coefficients, $F_a$ and $F_v$ specified in the Korean seismic design guide, underestimate the ground motion in short-period band and overestimate the ground motion in mid-period band, respectively, due to the high amplification in short period range, which represent the site-specific seismic response characteristics. These site-specific response characteristics indicate the potential of resonance in fortress walls during earthquake and furthermore could strongly affect the collapse of parapets resulted from seismic events in historical records.

A Study on Indirect Attachment Method of Compensation Materials to Increase Signal Intensity in Magnetic Resonance Imaging (자기공명영상검사 시 신호강도를 높이기 위한 보상물질의 간접부착 방식에 관한 연구)

  • Son, Soon-Yong
    • The Journal of the Korea Contents Association
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    • v.17 no.7
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    • pp.437-442
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    • 2017
  • Previously, studies on compensation material to increase the signal intensity have been conducted which does not affect the reading of images. However, the compensation material has a concern on patient infection as it is attached directly on the skin. Therefore, in this study, we tested an indirect attachment of the compensation material as an alternative method of the direct attachment. The silicon compensation material was fabricated in the form of a cylindrical bar and attached to each element of the 8 channel head coil. Then the signal intensities of the water phantom pre and post application of the silicon were measured. T1 and T2-weighted images were acquired using an 8-channel head coil and a 3.0T superconducting MRI. Signal intensities were measured by using an image measuring program. Paired t-test was used to verify if there were significant differences. The signal intensity before application of the silicon was significantly increased by 3.39% and 2.62% in T1 and T2 weighted images, respectively. Although the indirect attachment method had a limitation to completely replace the existing method, it was considered to be useful in patients with infectious diseases such as diabetic complications since it had a meaningful improvement in signal intensity based on the filling factor increase.

WZ Cephei: A Dynamically Active W UMa-Type Binary Star

  • Jeong, Jang-Hae;Kim, Chun-Hwey
    • Journal of Astronomy and Space Sciences
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    • v.28 no.3
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    • pp.163-172
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    • 2011
  • An intensive analysis of 185 timings of WZ Cep, including our new three timings, was made to understand the dynamical picture of this active W UMa-type binary. It was found that the orbital period of the system has complexly varied in two cyclical components superposed on a secularly downward parabola over about 80y. The downward parabola, corresponding to a secular period decrease of $-9.{^d}97{\times}10^{-8}y^{-1}$, is most probably produced by the action of both angular momentum loss (AML) due to magnetic braking and mass-transfer from the massive primary component to the secondary. The period decrease rate of $-6.^{d}72{\times}10^{-8}y^{-1}$ due to AML contributes about 67% to the observed period decrease. The mass flow of about $5.16{\times}10^{-8}M_{\odot}y^{-1}$ from the primary to the secondary results the remaining 33% period decrease. Two cyclical components have an $11.^{y}8$ period with amplitude of $0.^{d}0054$ and a $41.^{y}3$ period with amplitude of $0.^{d}0178$. It is very interesting that there seems to be exactly in a commensurable 7:2 relation between their mean motions. As the possible causes, two rival interpretations (i.e., light-time effects (LTE) by additional bodies and the Applegate model) were considered. In the LTE interpretation, the minimum masses of $0.30M_{\odot}$ for the shorter period and $0.49M_{\odot}$ for the longer one were calculated. Their contributions to the total light were at most within 2%, if they were assumed to be main-sequence stars. If the LTE explanation is true for the WZ Cep system, the 7:2 relation found between their mean motions would be interpreted as a stable 7:2 orbit resonance produced by a long-term gravitational interaction between two tertiary bodies. In the Applegate model interpretation, the deduced model parameters indicate that the mechanism could work only in the primary star for both of the two period modulations, but could not in the secondary. However, we couldn't find any meaningful relation between the light variation and the period variability from the historical light curve data. At present, we prefer the interpretation of the mechanical perturbation from the third and fourth stars as the possible cause of two cycling period changes.

Role of Anxiety in Concealed Information Test : an fMRI study (숨긴정보검사에서 불안의 역할 : fMRI 연구)

  • Eum, Yeong-Ji;Eom, Jin-Sup;Park, Kwang-Bai;Sohn, Jin-Hun
    • Science of Emotion and Sensibility
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    • v.14 no.2
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    • pp.227-234
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    • 2011
  • The purpose of present study was to examine brain functions associated with intention to conceal information. Kubo & Nittono(2009) and Verschuere et al.(2009) studied the intention to conceal information using P300 amplitude. On the basis of these two studies, present study attempted to identify brain area while participants were performing concealed information test. 19 healthy college students participated in fMRI-based concealed information test. Participants' name were used as concealed information. The test was performed in two conditions. In the intention condition, participants were instructed to try leaving their names undetected by suppressing their brain response to it. In the no intention condition, participants performed the test without intention to conceal. The fMRI results showed that the right anterior cingulated cortex (Rt. ACC), and left orbito-frontal cortex (Lt. OFC) activations were greater in the deceptive condition than the truth condition. These finding confirmed that ACC is area a deception-specific process as shown in the previous fMRI study. The OFC activation was also observed in the deceptive condition. The OFC is an area known as associated with emotional response such as anxiety, fear, and guilty. The anxiety induced while participants were intended to conceal information might be related to the OFC activation.

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An fMRI study on the cerebellar lateralization during visuospatial and verbal tasks (공간 및 언어 과제 수행 시 소뇌의 편측화에 관한 뇌 기능 연구)

  • Chung, Soon-Cheol;Sohn, Jin-Hun;Choi, Mi-Hyun;Lee, Su-Jeong;Yang, Jae-Woong;Lee, Beob-Yi
    • Science of Emotion and Sensibility
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    • v.12 no.4
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    • pp.425-432
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    • 2009
  • The purposes of the study were to examine cerebellar areas and lateralization responsible for visuospatial and verbal tasks using functional Magnetic Resonance Imaging(fMRI). Eight healthy male college students($21.5\;{\pm}\;2.3$ years) and eight male college students($23.3\;{\pm}\;0.5$ years) participated in this fMRI study of visuospatial and verbal tasks, respectively. Functional brain images were taken from 3T MRI using the single-shot EPI method. All functional images were aligned with anatomical images using affine transformation routines built into SPM99. The experiment consisted of four blocks. Each block included a control task(1 minute) and a cognitive task(1 minute). A run was 8 minutes long. Using the subtraction procedure, activated areas in the cerebellum during the visuospatial and verbal tasks were color-coded by t-score. A cerebellar lateralization index was calculated for both cognition tasks using number of activated voxels. The activated cerebellar regions during the both cognition tasks of this study agree with previous results. Since the number of activated voxels of the left and right cerebellar hemisphere was almost same, there was no cerebellar lateralization for both cognition tasks.

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