• Progress in Medical Physics
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• v.21 no.2
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• pp.209-217
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• 2010

Retinal prostheses are being developed to restore vision for the blind with retinal diseases such as retinitis pigmentosa (RP) or age-related macular degeneration (AMD). Since retinal prostheses depend upon electrical stimulation to control neural activity, optimal stimulation parameters for successful encoding of visual information are one of the most important requirements to enable visual perception. Therefore, in this paper, we focused on retinal ganglion cell (RGC) responses to different voltage stimulation parameters and compared threshold charge densities in normal and rd1 mice. For this purpose, we used in vitro preparation for the retina of normal and rd1 mice on micro-electrode arrays. When the neural network of rd1 mouse retinas is stimulated with voltage-controlled pulses, RGCs in degenerated retina also respond to voltage amplitude or voltage duration modulation as well in wild-type RGCs. But the temporal pattern of RGCs response is very different; in wild-type RGCs, single peak within 100 ms appears while in RGCs in degenerated retina multiple peaks (~4 peaks) with ~10 Hz rhythm within 400 ms appear. The thresholds for electrical activation of RGCs are overall more elevated in rd1 mouse retinas compared to wild-type mouse retinas: The thresholds for activation of RGCs in rd1 mouse retinas were on average two times higher ($70.50{\sim}99.87\;{\mu}C/cm^2$ vs. $37.23{\sim}61.65\;{\mu}C/cm^2$) in the experiment of voltage amplitude modulation and five times higher ($120.5{\sim}170.6\;{\mu}C/cm^2$ vs. $22.69{\sim}37.57\;{\mu}C/cm^2$) in the experiment of voltage duration modulation than those in wild-type mouse retinas. This is compatible with the findings from human studies that the currents required for evoking visual percepts in RP patients is much higher than those needed in healthy individuals. These results will be used as a guideline for optimal stimulation parameters for upcoming Korean-type retinal prosthesis.

• Journal of Korean Society of Forest Science
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• v.65 no.1
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• pp.80-91
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• 1984

The purposes of this study are to analyze and forecast the domestic demand for papers by regression models with time-series data (1965-81). For the period of 1965-81, the real GNP of Korea grew at annual average increase rate of 8.8 percent. On the other hand, the domestic demand of papers grew at annual average increase rate of 17.9 percent in this period. Especially, the annual average increase rate for board-papers accounted to 25.8 percent. To analyze domestic demand for papers, GNP, per capita GNP, price findex of papers, production activity index of the major papers consuming industries and price index of substitutive goods were selected as independent variables. The expected values of domestic demand for papers were computed by forecasting equations as follows. T-values are in parentheses. ${\ell}nDDP=2.452+1.986{\ell}nPG-0.844{\ell}nPWI$ $(33.397)^*\;(-6.149)^*\;R^2=0.997$ ${\ell}nDDP=6.468+0.827{\ell}nPDA$ $(17.403)^*\;R^2=0.950$ DDP : Domestic demand for papers PG : Real GNP per capita (1,000 won) PWI : Real price index of papers (1980 = 100) PDAV : Production activity index of the major papers consuming industries The results analyzed and forecasted by these models are summarized as follows: The domestic demand for papers had positive correlation toward per capita GNP and production activity index of the major papers consuming industries. Per capita GNP elasticity of the domestic demand for papers was the most elastic among independent variables. The price elasticity of domestic demand for papers had negative sign and inelastic. These were not only statistically significant but theoretically compatible. The domestic demand for papers was projected to be 3,152-4,470 thousand mit in 1991, representing at annual increase rate of 5.0-12.4 percent during the period of 1982-91. Domestic demand for papers per capita was projected to be 69.1-98.0 kg in 1991.

• Childhood Kidney Diseases
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• v.4 no.2
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• pp.102-110
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• 2000

Purpose : Intravenous infusion of albumin has been widely und to relieve severe nephrotic edema in spite of beneficial or harmful effects. The purpose of this study is to examine the harmful effect of albumin on the clinical course of steroid sensitive nephrotic syndrome(SSNS). Method : We prospectively randomized the patients with nephrotic syndrome(biopsy proven or clinically compatible to minimal change nephrotic syndrome) into the albumin group(20$\%$ albumin 1 g/kg) or control group(5$\%$ D/W) between March 1997 and September 1999 at Ewha University Mokdong Hospital. We compared the clinical course of the albumin group(n=13) with the control group(n=13). Results : 1. The duration of steroid therapy until complete remission in the albumin group was significantly longer than the control group($13.7{\pm}6.4\;days\;vs\;7.5{\pm}2.8\;days$)(P<0.05). 2. The remission duration to the first relapse was significantly shorter in the albumin group ($94{\pm}63.5$ days) than the control group($190{\pm}106.4$ days)(P< 0.05). There was no significant difference in the relapse rate within 1 year after complete remission[77$\%$ (10/13) vs 46$\%$ (6/13)](P>0.05) and the relapse frequency per year($1.9{\pm}0.8\;vs\;1.5{\pm}0.5$) between the albumin and control groups. 3. Spot urine protein/creatinine ratio significantly increased in the albumin group at post-albumin 2, 4 days(P<0.05). There was no significant difference in the change of the daily percent weight loss, blood pressure, serum Na, K concentration between the albumin and control groups. Conclusion : Albumin infusion in SSNS delayed the response to steroid and shortened the remission duration to the first relapse. Albumin should be carefully used in nephrotic edema.

• The Journal of the Petrological Society of Korea
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• v.4 no.1
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• pp.31-48
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• 1995

The Jurassic Kwanaksan stock, so far known to be composed of biotite granite only, has the mineral assemblage of quartz+K-feldspar+plagioclase+biotite${\pm}$gernet. The lithology of the stock is classified as alkali feldspar granite by their mode and plagioclase compositions (An<5). Subsolvus feldspars, rather early crystallization of biotite, and shallow emplacement depth estimated from Q-Ab-Or diagram suggest hydrous nature of the magma, which contrasts with anhydrous A-type like geochemistry described below. Major and trace element compositions of the Kwanaksan stock are distinct from those of the adjacent Seoul batholith, suggesting a genetic difference between the two, The Kwanaksan stock shows geochemical characteristics similar to A-type granite in contrast to most other Mesozoic granites in Korea, in that it has high $SiO_2$(73~78wt%), $Na_2O+K_2O$, Ga(27~47 ppm). Nb(22~40 ppm), Y(48~95 ppm), Fe/Mg and Ga/Al, and low CaO(<0.51 wt%). Ba (8~75 ppm) and Sr(2~23 ppm). However, it has lower Zr and LREE and higher Rb(384~796 ppm) than typical A-type granite. LREE-depleted rare earth element pattern with strong negative Eu anomaly of previous studies is reinterpreted as representing source magma characteristics. The residual material during partial melting is not compatible with pyroxenes, amphibole or garnet, while significant amount of plagioclase is required. Similarity of geochemistry of the Kwanaksan stock to A-type granite suggests the origin of the stock has a chose relationship with that of A-type granite. These observations lead us to propose that the Kwanaksan stock was formed by partial melting of felsic source rock.

• Advances in pediatric surgery
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• v.8 no.1
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• pp.16-22
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• 2002

Between March 1999 and January 2000, 82 boys with the diagnosis of inguinal hernias (12 bilateral and 70 unilateral hernias), underwent Ultrasound (US) examination of both sides of the groin, a total of 164 inguinal imaging prior to surgery. The patients ages ranged from 3 days to 12 years with a mean of 32.6 months. Ninty four examinations were on the clinically symptomatic side and 70 were on the asymptomatic side. The US criteria for the diagnosis of an inguinal hernia were as follows: 1) visceral hernia, the presence of bowel loops, or omentum in the inguinal canal, 2) communicating hydrocele, the presence of fluid in the processus vaginalis, 3) widening of patent processus vaginalis at the level of internal inguinal ring. The width of patent processus vaginalis at the level of internal inguinal ring over 4 mm is considered an occult hernia. Among the 94 symptomatic groins, US findings showed 31 (33%) visceral hernias, 18 (19%) communicating hydroceles, and 38 (41%) widening of the internal inguinal ring, and 7 (7%) groins without abnormalities. In 70 asymptomatic groins, there were 4 (6%) visceral hernias, 5 (7%) communicating hydroceles, 11 (16%) widening of the internal inguinal ring, and 50 (70%) groins without abnormalities. Among the 70 asymptomatic groins there were US abnormalities in 20 (28%). One hundred and seven groins with positive US findings were surgically explored. Among 107 operated sites, the operative findings were compatible with the US diagnosis in 104, a sensitivity for US of 97.2%. In patients with US findings of widening of internal inguinal ring (>4 mm), there was patent processus vaginalis in 36 out of 38 symptomatic groins and 10 of 11 asymptomatic groins. The sensitivity of US to the operative findings in widening of internal inguinal ring was 93.8%. For visceral hernia and communicating hydrocele, the sensitivity of positive US findings was 100%. Ultrasonography for inguinal hernias appears to be a rapid, reliable, and noninvasive screening diagnostic tool with high positive specificity. Therefore, we recommend the use of US as a routine diagnostic tool in pediatric patients with inguinal hernias and hydroceles.

• Tuberculosis and Respiratory Diseases
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• v.53 no.2
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• pp.173-182
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• 2002

Background : Nontuberculous mycobacteria (NTM) have usually been considered to be contaminants of colonizers when isolated from respiratory specimens in Korea, where there is a high prevalence of tuberculosis and a low rate of HIV infections. Therefore, there has been few studies on the clinical significance of NTM species in immunocompetent patients were investigated. Methods : Thirty-five NTM isolates, for which species identification was requested by the treating physicians during 1999 at the Asan Medical Center, were retrospectively analyzed. They were identified to the species level by mycolic acid analysis using high-performance liquid chromatography. The medical records of the patients with the NTM isolates were reviewed to identify those patients who met the American Thoracic Society (ATS)'s criteria for mycobacterial pulmonary infection. Their antimicrobial susceptibility data were compared with the clinical outcomes. Results : The NTM were identified as M. intracellulare (6 isolates), M. avium (5), M. abscessus (5), M. gordonae (5), M. terrae complex (4), M. szulgai (2), M. kansasii (2), M. fortuitum (2), M. peregrinum (1), M. mucogenicum (1), M. celatum (1), and M. chelonae (1). All 35 patients showed clinical symptoms and signs of chronic lung disease, but none had a HIV infections; 16 (45.7%) patients were found to be compatible with a NTM pulmonary infection according to the ATS criteria, 5 and 4 cases were affected with M. intracellulare and M. abscessus, respectively; 8 patients had a history of pulmonary tuberculosis. 13 patients received antimycobacterial therapy for an average of 21 months and 9 patients were treated with second-line drugs. Only 4 patients had improved radiologically. Conclusion : A NTM should be considered a potential pathogen of pulmonary infections in immunocompetent patients with chronic pulmonary diseases. Most NTM infections were left untreated for a prolonged period and showed a poor outcome as a result, M. intracellulare and M. abscessus were the two most frequent causes of NTM pulmonary infections in this study. Species identification and antimycobacterial susceptibility tests based on the species are needed for the optimum management of a NTM pulmonary infection in patients.

• Progress in Medical Physics
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• v.14 no.2
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• pp.124-130
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• 2003

Currently, as a consequence of PACS (Picture Archiving Communication System) implementation many hospitals are replacing conventional film-type interpretations of diagnostic medical images with new digital-format interpretations that can also be saved, and retrieve However, the big limitation in PACS is considered to be the lack of mobility. The purpose of this study is to determine the optimal communication packet size. This was done by considering the terms occurred in the wireless communication. After encoding medical image using JPGE2000 image compression method, This method embodied auto-error correction technique preventing the loss of packets occurred during wireless communication. A PC class server, with capabilities to load, collect data, save images, and connect with other network, was installed. Image data were compressed using JPEG2000 algorithm which supports the capability of high energy density and compression ratio, to communicate through a wireless network. Image data were also transmitted in block units coeded by JPEG2000 to prevent the loss of the packets in a wireless network. When JPGE2000 image data were decoded in a PUA (Personal Digital Assistant), it was instantaneous for a MR (Magnetic Resonance) head image of 256${\times}$256 pixels, while it took approximately 5 seconds to decode a CR (Computed Radiography) chest image of 800${\times}$790 pixels. In the transmission of the image data using a CDMA 1X module (Code-Division Multiple Access 1st Generation), 256 byte/sec was considered a stable transmission rate, but packets were lost in the intervals at the transmission rate of 1Kbyte/sec. However, even with a transmission rate above 1 Kbyte/sec, packets were not lost in wireless LAN. Current PACS are not compatible with wireless networks. because it does not have an interface between wired and wireless. Thus, the mobile JPEG2000 image viewing system was developed in order to complement mobility-a limitation in PACS. Moreover, the weak-connections of the wireless network was enhanced by re-transmitting image data within a limitations The results of this study are expected to play an interface role between the current wired-networks PACS and the mobile devices.

• Korean Journal of Environment and Ecology
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• v.30 no.2
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• pp.165-172
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• 2016

Mallard and Spot-billed ducks that are typical wintering water birds use the wide rice field in the center of the water system as a wintering ground. I try to figure out the daily movement distance from Home-Range to wintering ground for mallard and spot-billed ducks in Mangyunggang, Dongjingang where located in central region. In 2015 wintering period by using a Cannon-net, I attached WT-300 to 5 mallard and 5 spot-billed ducks. Daily movement distance is an overall average 0.89km, the largest distance was 31.09km. Daily movement distance of mallard was 0.97km, the largest distance was 28.78km. Daily movement distance of Spot-billed ducks was 0.80km, the largest distance was 33.39km. Home-Range analysis is used by the SHP files that is compatible with GIS and ArcGIS 9.0 Animal Movement Extension, it was analyzed using the Minimum Convex Polygon Method (MCP) and the Kernel Density Estimation (KDE). The behavior rights of two kinds of ducks was $490.34km^2$ by Minimum Convex Polygon Method (MCP) ($SD=311.20km^2N=10$), an important habitats Kernel Density Estimation (KDE 50%) was $42.24km^2$. Home-Range of Mallard (MCP) was $568.02km^2$, it is wider than home-range(MCP) of spot-billed duck $397.13km^2$ relatively, the core habitats of mallard is $53.05km^2$, it is wider than mallard's core habitats(KDE 50%) $29.26km^2$ relatively.

• Journal of Chest Surgery
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• v.36 no.5
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• pp.309-315
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• 2003

Background: To avoid the adverse effects of cardiopulmonary bypass and to overcome late vein graft failure we routinely peformed off-pump total arterial coronary revascularization. Material and Method: From July 2000 to August 2001, 104 consecutive patients underwent first elective off-pump total arterial coronary revascularization. Both internal mammary, radial and gastroepiploic arteries were used. Sequential and composite grafts were used to achieve complete revascularization. Perioperative adverse events and postoperative angiograms were analyzed. Result: A total of 252 arterial conduits were used with an average of 2.47 grafts per patient. A total of 326 distal anastomosis were performed with a mean of 3.13 distal anastomosis per patient. Cross over to on-pump occurred in seven patients (6.7%). Of these 4 were due to unstable hemodynamics during lateral or posterior wall stabilization as a result of cardiomegaly and 3 were due to uncontrolled bleeding during dissection of diffusely dimunitive deeply placed intramyocardial coronary arteries. There were no opeartive deaths. Two cases of perioperative myocardial infarction and transient neurologic complications occurred, respectively. Of the 312 distal anastomoses, 308 (98.7%) were compatible with Fitz-Gibboll A or B patency grading. Conclusion: Off-pump total arterial coronary revascularization was technically feasible in most elective cases with satisfactory early results. However, on-pump coronary bypass surgery should be considered in difficult circumstances, such as cardiomegaly or unfavorable anatomy of the target coronary artery.

• Korea journal of population studies
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• v.29 no.1
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• pp.185-207
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• 2006

Predominant explanations of the persistence of sex segregation ill occupations link job choices to profoundly gendered responses to childbearing and other family demands, arguing that women are more likely to seek jobs which are in some sense compatible with motherhood, either because they are family friendly (flexible, low intensity work) or because they are easy to exit and re-enter. In this paper, I examine the effect of occupational sex segregation on job exits into the labor market among women, with a special attention to the role of childbearing and child rearing. I use data from detailed employment histories gathered from the National Longitudinal Survey of Youth (NLSY) in continuous time event history models. My results indicate that women in female dominated jobs are less likely to exit their jobs than women in other types of occupations. Further this relationship is not shaped by motherhood. While mothers or pregnant women are more likely to leave work, mothers in female-dominated occupations are slightly less likely to leave employment than mothers in other occupations. These results are not consistent with the ideas that women's choice of female-dominated occupations expresses a gendered identity and women strategically seek jobs which accommodate maternal roles. Taken together, my findings do not provide support to the idea that women choose female-dominated occupations because they are easier to integrate with motherhood (except for the pregnancy period).