• KDI Journal of Economic Policy
• /
• v.31 no.1
• /
• pp.169-206
• /
• 2009

This study stems from a question, "How should we understand the pattern of the Korean economy after the 1990s?" Among various analytic methods applicable, this study chooses a Structural Vector Autoregression (SVAR) with long-run restrictions, identifies diverse impacts that gave rise to the current status of the Korean economy, and differentiates relative contributions of those impacts. To that end, SVAR is applied to four economic models; Blanchard and Quah (1989)'s 2-variable model, its 3-variable extensions, and the two other New Keynesian type linear models modified from Stock and Watson (2002). Especially, the latter two models are devised to reflect the recent transitions in the determination of foreign exchange rate (from a fixed rate regime to a flexible rate one) as well as the monetary policy rule (from aggregate targeting to inflation targeting). When organizing the assumed results in the form of impulse response and forecasting error variance decomposition, two common denominators are found as follows. First, changes in the rate of economic growth are mainly attributable to the impact on productivity, and such trend has grown strong since the 2000s, which indicates that Korea's economic growth since the 2000s has been closely associated with its potential growth rate. Second, the magnitude or consistency of impact responses tends to have subsided since the 2000s. Given Korea's high dependence on trade, it is possible that low interest rates, low inflation, steady growth, and the economic emergence of China as a world player have helped secure capital and demand for export and import, which therefore might reduced the impact of each sector on overall economic status. Despite the fact that a diverse mixture of models and impacts has been used for analysis, always two common findings are observed in the result. Therefore, it can be concluded that the decreased rate of economic growth of Korea since 2000 appears to be on the same track as the decrease in Korea's potential growth rate. The contents of this paper are constructed as follows: The second section observes the recent trend of the economic development of Korea and related Korean articles, which might help in clearly defining the scope and analytic methodology of this study. The third section provides an analysis model to be used in this study, which is Structural VAR as mentioned above. Variables used, estimation equations, and identification conditions of impacts are explained. The fourth section reports estimation results derived by the previously introduced model, and the fifth section concludes.

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

• Radiation Oncology Journal
• /
• v.22 no.2
• /
• pp.130-137
• /
• 2004

Purpose : In radiotherapy for cervix cancer, both 3-dimensioal radiotherapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) could reduce the dose to the small bowel (SB), while the small bowel displacement system (SBDS) could reduce the SB volume in the pelvic cavity. To evaluate the effect of the SBDS on the dose to the SB in 3D-CRT and IMRT plans, 3D-CRT and IMRT plans, with or without SBDS, were compared. Materials and Methods : Ten consecutive uterine cervix cancer patients, receiving curative radiotherapy, were accrued. Ten pairs of computerized tomography (CT) scans were obtained in the prone position, with or without SBDS, which consisted of a Styrofoam compression device and an individualized custom-made abdominal immobilization device. Both 3D-CRT, using the 4-field box technique, and IMRT plans, with 7 portals of 15 MV X-ray, were generated for each CT image, and proscribed 50 Gy (25 fractions) to the isocenter. For the SB, the volume change due to the SBDS and the DVHs of the four different plans were analyzed using palled t-tests. Results : The SBDS significantly reduced the mean SB volume from 522 to 262 cm$^{3}$ (49.8$\%$ reduction). The SB volumes that received a dose of 10$\~$50 Gy were significantly reduced in 3D-CRT (65$\~$80$\%$ reduction) and IMRT plans (54$\~$67$\%$ reduction) using the SBDS. When the SB volumes that received 20$\~$50 Gy were compared between the 3D-CRT and IMRT plans, those of the IMRT without the SBDS were significantly less, by 6$\~$7$\%$, than those for the 3D-CRT without the SBDS, but the volume difference was less than 1$\%$ when using the SBDS. Conclusion : The SBDS reduced the radiation dose to the SB in both the 3D-CRT and IMRT plans, so could reduce the radiation injury of the SB.

• Food Science and Preservation
• /
• v.23 no.6
• /
• pp.797-803
• /
• 2016

In this study, we investigated the effect of fermentation conditions on the amylolytic and proteolytic activities of Aspergillus luchuensis strain 74-5 and Aspergillus oryzae strain 75-2, which are used in the preparation of the starter culture, for Takju (Korean traditional rice wine). The starter culture was optimized using different conditions, such as inoculum size, inoculation temperature, and incubation time. The enzyme activities under each condition were measured. In the A. luchuensis strain 74-5 starter culture, the ${\alpha}-amylase$ and glucoamylase activities increased, however the activity of acidic protease decreased as the diluent to starter culture ratio increased. In the A. oryzae 75-2 starter culture, all enzyme activities were maintained at a higher level even at 5% inoculation ratio. Higher enzyme activities were observed in the middle range of inoculation temperature (35, $40^{\circ}C$), than in the lower range (20, $30^{\circ}C$). Enzyme activity in the starter culture varied with incubation time, however it was the highest at 144 and 120 hr, respectively, for A. luchuensis strain 74-5 and A. oryzae strain 75-2. The spore count of the starter culture was approximately $2{\times}10^7$ during fermentation, out of which contamination by aerobic bacteria was about $3{\times}10^3$. The results suggested that the starter culture of each strain could be used as an inoculum for fermentation. However, we needs to conduct further research for the selection of suitable diluting agents as well as drying methods to reduce the contamination by aerobic bacteria, while retaining the enzyme activity.

• The Journal of the Petrological Society of Korea
• /
• v.26 no.3
• /
• pp.201-219
• /
• 2017

The Jinan Basin which includes Maisan locates in the central part of the northern boundary of the Yeongnam Massif. The basement rocks of the Jinan Basin and surrounding area are Precambrian gneiss and Mesozoic granite which were exposed on the surface before Cretaceous. The Jinan Basin, one of the Cretaceous pull-apart basins in South Korea, formed along the Yongdong-Gwangju fault system. Maisan is composed of conglomerate deposited in the eastern slope of the Jinan Basin showing the shape of horse ears and the unusual topography where many tafonies were developed. The strike slip fault that caused the Jinan Basin was connected to the deep depth so that the magma formed at 200 km depth could have extruded on the surface causing active volcanic activity in and around the Jinan basin. As a result, Cheonbansan composed of pyroclastic rocks, Gubongsan consisting of volcanic neck and WoonilamBanilam formed by the lava flow, appear around Maisan forming a specific terrain. After the formation of the Jinan Basin and surrounding volcanic rocks, they uplifted to form mountains including Masian; the uplifting time may be ca. 69-38 Ma. At this time, the Noryeong mountain range may be formed in the regions which extended from Chugaryeong through Muju and Jinan to Hampyeong dividing the Geumgang and Seomjingang water systems. Due to the ecological barrier, the Noryeong mountain range, Coreoleuciscus splendidus living in the Geumgang water systems was differentiated from that in the Soemjingang water system. In addition, the Geumgang and Mangyeong-Dongjingang water systems were separated by the Unjangsan, which developed in the NNW direction. As a result, diverse ecosystem have been established in and around Maisan and at the same time, diverse cultural and historical resources related to Maisan's unique petrological features, were also established. Therefore, Maisan and surrounding area can be regarded as a place where a geotourism can be successfully established by combining the ecological, cultural and historical resources with a geological heritage. Therefore Maisan and surrounding areas have a high possibility to be a National Geopark and UNESCO Global Geopark.

• Journal of dental hygiene science
• /
• v.15 no.3
• /
• pp.259-264
• /
• 2015

For this experiment, specimen was manufactured by injecting polymer and monomer into silicon mold with volume ratio of 2.5:1 based on ISO 20795-2 so that average thickness, width and length of specimen would be maintained as 3.3 mm, 10.0 mm and 65.0 mm, respectively depending on spray on technique. Specimen was divided into 3 groups ($25^{\circ}C$, $40^{\circ}C$, $70^{\circ}C$) depending on polymerization temperature and 10 specimen was manufactured for each group and it was polymerized in water tank of ${\pm}1^{\circ}C$ under the setting condition of polymerization time of 15 minutes and pressure of 3 bar. After keeping specimen in distilled water of $37^{\circ}C$ for over 48 hours before experiment, flexural strength (FS) and elasticity modulus (EM) of specimen being tested by using Intron (3344; Instron; Instron). SPSS ver. 16.0 was used for analysis and post-hoc test of Scheffe was performed after using one-way ANOVA. When comparing mean value of FS of resin for orthodontics, it was represented in the range of 71.500 MPa for $25^{\circ}C$ group, 74.920 MPa for $40^{\circ}C$ group and 76.880 MPa for $70^{\circ}C$ group and difference was shown in the order of $25^{\circ}C$ group <$40^{\circ}C$ group <$70^{\circ}C$ group but such difference was not significant statistically (p=0.052). Result of EM mean value of resin for orthodontics was more polymerization temperature was high, the more was significant difference represented in the order of $25^{\circ}C$ group <$40^{\circ}C$ group <$70^{\circ}C$ group (p<0.039).

• Journal of Life Science
• /
• v.25 no.3
• /
• pp.276-284
• /
• 2015

This study was designed to investigate the effect of garlic shoot extract administration on serum and liver tissue lipid levels in hyperlipidemic rats. The rats were fed a 45% high-fat diet to induce hyperlipidemia. They were then administered garlic shoot extract (50%) and ethanol extract (75%) at 200 mg/kg B.W./day (GSA-1, GSB-1) and 400 mg/kg B.W./day (GSA-2, GSB-2) for 5 weeks. The total lipid and triglyceride contents in serum were lowest in the GSB-2 group, and the total cholesterol content was significantly lower in the GSA-2 and GSB-2 groups than in the control group. The high density lipoprotein (HDL)-cholesterol content of the GSB-2 group was similar to that of the normal group. The low density lipoprotein (LDL) and very low density lipoprotein (VLDL)-cholesterol contents were significantly lower in the GSB-1 and GSB-2 group than in the control group. atherogenic index (AI) and cardiac risk factor (CRF) were lowest in the GSB-2 group (0.58 and 1.57, respectively). Aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) activities were significantly higher in the control group than in the normal group, and the levels of AST, ALT, and ALP were significantly lower in the GSA-2 and GSB-2 groups than in the control group. The total lipid content in liver tissue was significantly lower in all the experimental groups compared to that of the control group, but it was not significantly different among the experimental groups. The total cholesterol and triglyceride content in liver tissue was lowest in the GSB-2 group. Antioxidant activity in serum and liver tissue was highest in the GSB-2 group (40.16% and 47.41%, respectively).The thiobarbituric acid reactive substance (TBARS) content in serum and liver tissue was lowest in the GSB-2 group, with the significant difference. Our results suggest that garlic shoot extracts may improve lipid metabolism in serum and liver tissue and potentially reduce hyperlipidemia.

• Journal of Life Science
• /
• v.22 no.11
• /
• pp.1529-1537
• /
• 2012

In order to determine the effective concentration, 2, 7, and 14 brix black garlic extracts (BGE) were fed to restraint stressed rats and the lipid metabolism was analyzed. The dietary intake of the 14 brix BGE-fed group was $547.64{\pm}13.99$ g/4 weeks and it was significantly higher than that of the control group. The weight of all organs from the all BGE-fed groups showed no significant differences. While BGE concentration increased, BGE-fed groups tend to have low content of blood glucose. It was the lowest in the 14 brix BGE-fed group ($121.32{\pm}3.50$ mg/dl). Total cholesterol content was $54.54{\pm}1.63{\sim}65.84{\pm}2.61$ mg/dl. Total cholesterol content of the 14 brix BGE-fed group was the lowest and, in addition, lower than the normal group. Triglyceride content of serum showed the same tendency. HDL-cholesterol concentrations of the restraint stressed control (RSC) group were significantly higher than those of 7 and 14 brix BGE-fed groups. LDL and VLDL-cholesterol contents showed contrary results. GOT, GTP, and ALP activity of serum were lower when BGE concentration was higher. It is expected that BGE has a liver protective activity. In the liver, total lipids and triglyceride contents were significantly lower in BGE-fed groups than in the ISC group. However, total cholesterol content showed no significant difference between groups. TBARS content in liver of the 2 brix BGE-fed group was not significantly different than control, while 7 and 14 brix BGE-fed groups were lower than control. Glycogen content in the liver was only significantly lower in the 14 brix BGE-fed group than in the RSC group. Findings indicate that feed of BGE over 7 brix contributes to resolving the restraint-stressed rats by improving the lipid metabolism and liver protective activity.

• Journal of Life Science
• /
• v.19 no.11
• /
• pp.1547-1552
• /
• 2009

This study was carried out to evaluate the supplementation effect of dietary natural plant extracts (NP: $Coxynil^{(R)}$, $Growell^{(R)}$ and $Respowell^{(R)}$) on broiler chickens. Forty thousand male broilers with 7 days adaptation after hatching were fed experiment diets for 34 days. The supplementation effects of NP on growth performance, blood parameters and biopsy were examined with twenty thousand broilers as the treatment group. Twenty thousand broilers for the control group (CON) were fed the diet with salinomycin-6, clopidol-25, enramycin-1, and BMD-2.5. In the diet of the treatment group, the antibiotics were replaced with 0.03%, 0.035% and 0.03% of $Coxynil^{(R)}$, $Growell^{(R)}$ and $Respowell^{(R)}$, respectively. The weight gain of the treatment group was increased but the feed intake was decreased, indicating that feed efficiency was increased compared to the CON. The mortality of the NP group was also lower compared to the CON group (1,008 birds to 1,693 birds), showing positive dietary effects from natural plant extracts. In the activity of infectious bursal disease virus (IBDV) and new cattle disease virus (NDV) antibodies, the NP showed lower antibody titer levels for both of IBDV and NDV compared to the CON. The levels of total cholesterol, HDL-cholesterol, globulin, and IgG in blood did not show significant differences between the groups. In the microscopic tissue analysis, no significant differences were detected. These results may suggest that a complex of three natural plant extracts can be used as alternative antibiotics in broilers.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.425-426
• /
• 2013

IIIN계 물질 기반의 광 반도체는 직접 천이형 넓은 밴드갭 구조를 갖고 있기 때문에 적외선부터 가시광선 및 자외선까지를 포함한 폭 넓은 발광파장 조절이 가능하여 조명 및 디스플레이 관련 차세대 광원으로 많은 관심을 받고 있다. 일반적인 청색 및 녹색 발광영역의 활성층으로는 InGaN/GaN 다중양자우물구조를 사용하고 있으나, 장파장의 녹색 발광을 얻기 위해서는 인듐의 함유량이 증가하여야 한다. 하지만, 인듐의 함유량이 증가함에 따라서 InGaN/GaN 다중양자우물 구조내에서 인듐의 편석현상의 발생이 용이하게 되어 계면 특성을 저하할 뿐 아니라, 비발광 센터를 증가하여 발광 효율을 급격히 감소시키는 원인이 되고 있다. 또한, InGaN과 GaN의 큰 성장온도의 차이에 따라 800도 부근의 저온 영역에서 성장된 InGaN층이 1,000도 이상의 고온 영역에서 GaN층이 성장시 InGaN층의 열화 현상이 급격히 발생되고 있다. 이를 억제하기 위해서 금속유기화학증착법의 성장 변수 최적화, 응력제어, 도핑 등의 편석 억제기술 및 보호층이 사용되고 있다. 본 연구에서는 인듐함유량이 증가된 녹색 InGaN/GaN 다중양자우물구조에서 InGaN 우물층 상하부에 도입된 GaN 보호층에 따라 발생되는 양자우물구조의 광학 및 결정학적 특성 분석을 통해 GaN 보호층의 역할을 분석하고자 한다. 본 연구에서는 금속유기화학증착장치를 이용하여 사파이어 기판위에 GaN 템플릿을 성장하고, n-형 GaN, InGaN/GaN 다중양자우물구조 및 p-형 층을 성장하였다. 앞선 언급하였듯이, InGaN/GaN 다중양자우물구조내에 GaN 보호층의 역할을 규명하기 위하여 샘플 A의 경우는 보호층이 전혀 없는 구조이고, 샘플 B의 경우는 InGaN 우물층의 상단부에만, 샘플 C의 경우에는 우물층 상부 및 하단부 모두에 약 2.0 nm 두께의 GaN 보호층을 형성하였다. 이 보호층의 유무에 따른 다중양자우물구조의 계면 특성을 확인하기 위한 X-선 회절을 이용하였고, 광학적 특성을 확인하고 상온 포토루미네선스법을 이용하여 녹색 발광 파장의 변화 및 발광세기를 관찰하였다. 우선적으로, 상온 포토루미네선스법을 이용하여 각 샘플의 발광특성을 확인한 바 상하부 모두에 GaN 보호층이 존재하는 샘플 C의 경우 약 510 nm 부근에서 발광이 관찰되었지만, 상단부에 GaN 보호층이 존재하는 샘플 B는 약 495 nm영역에 발광이 확인되었다. 특히, 전혀 보호층이 존재하지 않는 샘플 A의 경우 약 440 nm에서 발광하는 현상을 관찰하였다. 이는 우물층 상단부 및 하단부에 존재하는 GaN 보호층이 In의 확산을 억제하는 것으로 판단된다. 또한, 발광파장 및 세기를 확인한 바, 보호층의 존재하지 않을수록 단파장화가 발생함에도 불구하고 발광세기는 급격히 약해지는 것으로 보아 계면특성이 저하되어 비발광센터가 증가되는 것으로 판단된다. 이를 구조적으로 확인하기 위하여 X-선 회절법을 통한 ${\omega}$/$2{\Theta}$ 스캔의 결과는 In의 0차 피크가 GaN 보호층이 없을 경우 GaN의 피크 방향으로 이동하는 것으로 보아 GaN 보호층은 우물층 성장 후 GaN 장벽층을 성장하기 위해 온도를 증가시키는 과정에서 In의 확산되는 것으로 판단된다. 또한, 하부 GaN 보호층의 경우 GaN 장벽층 성장 후 온도를 감소시키는 과정에서 성장되므로, 우물층으로부터 In의 탈착현상이 아닌 장벽층과의 상호 확산으로 판단된다. 또한, 계면특성을 확인하기 위해 InGaN의 X-선 위성 피크를 확인한 바 샘플 A의 경우 매우 넓고 약한 피크가 관찰된 반면, 보호층이 존재하는 샘플 B와 C의 경우 강하고 얇은 피크가 확인되었다. 이는 GaN 보호층의 도입으로 인해 계면특성이 향상되는 것으로 판단된다. 따라서, 우리는 InGaN/GaN 다중양자우물구조에서 GaN 보호층은 상부의 열화 억제 뿐아니라, 하부의 장벽층 및 우물층 사이의 상호확산을 억제하는 GaN 보호층의 도입을 통하여 우수한 계면 특성 및 비발광센터의 억제를 얻을 수 있을 것으로 생각되며, 이는 향후 GaN계 발광다이오드의 전계 발광특성을 증가하여 우수한 발광소자를 개발할 수 있을 것으로 기대된다.