Growth and Global Imbalances: The Role of Learning-by-Exporting

Rapidly growing developing economies have exported heavily and run current account surpluses. Empirical studies suggest that "learning-by-exporting" may be quantitatively large in developing countries and behind some of this dramatic growth. This paper explores if learning-by-exporting helps explain the key macroeconomic behavior of fast growing developing countries. It builds up a two country general equilibrium growth model in which a developing economy benefits from learning-by-exporting as it trades with a developed economy. As the benchmark, I consider a setup in which the policies are restricted to non-trade related ones by the World Trade Organization (WTO) and compare it to a model with "No-WTO restrictions". The optimal policies in the presence of WTO restrictions rationalize the observed current account surpluses of rapidly growing developing economies. However, if there were no WTO restrictions, the developing countries would manipulate their terms of trade rather than their current account, which improves the welfare of both developing and developed countries. This highlights the fact that terms of trade manipulation can be "win-win" in the presence of learning-by-exporting. This paper also considers a "Coordinated Policy" problem to obtain the first-best outcomes for the world. In this setup, the developing country's terms of trade deteriorate even more and it runs a greater current account deficit relative to the "No-WTO Restrictions" case

Structural Change in the Trend and Cycle in Korea

On the basis of regression of consumption on output, we develop a new approach to identify a structural break in business cycles. Using this approach, we find that a structural change in the trend and cycle in Korea occurred in 1993 and that the business cycles in Korea started to show the regularities of emerging market business cycles beginning in 1993. To explain these, we estimate the parameters of the productivity process in Korea, using data on Solow residuals. Our estimates show that the relative importance of trend growth shocks in the post-break period increased by a factor of 2.56 from that in the pre-break period

Experimental Study of the Injection System for CO2 Geologic Storage Demonstration

AbstractThe worldwide issue of greenhouse gas reduction has recently drawn great attention to carbon capture and storage (CCS). Almost CCS studies have been focused in the capture technology of carbon dioxide and the geological investigation for underground storage. The study of mechanical injection system for carbon dioxide has not implemented nearly. We are intended to develop a ground system for underground injection of carbon dioxide. In this study, we made lab-scale underground injection system and implemented injection simulation test experimentally. The 10,000 ton/year pilot plant for geological storage of carbon dioxide will be designed on the base of these test results. Major components of the lab-scale underground injection system include a pressure pump and an in-line heater to bring liquid carbon dioxide into its supercritical state. Test results assure that this system readily achieves the designed injection pressure and temperature, showing satisfactory control performance

Relative Contribution among Physical Fitness Factors Contributing to the Performance of Modern Pentathlon

This study reveals the relationship between physical fitness factors and performance in modern pentathlon and identifies the contribution of each physical factor to overall performance. The physical fitness assessment data and the competition records collected by the Korean national team pentathletes for the years 2005 to 2019 were tracked. The correlation between the competition records and fitness factors was confirmed by correlation analysis. In addition, the physical factors affecting performance were identified through multiple regression analysis, and the average difference between national and international competitions was verified by t-test. The first result was that fencing, swimming, and horseback riding rankings were more relevant to the overall pentathlon performance score than the combined rankings in national competitions. In the international competitions, performance in the combined running and shooting event was more relevant than fencing, swimming, and horseback riding. Second, the basic fitness factors of grip strength and sergeant jump and the specific fitness factors of leg strength—left and right average flexor were correlated with overall pentathlon performance national competitions. However, in international competitions, sergeant jump, 20 m shuttle run, reaction time, lung capacity, and back strength were correlated (presented in high to low order). In terms of the specific fitness factors, relative (%BW) and absolute (Nm) leg strength—left and right average flexor, lower body anaerobic fatigue rate, half squat, relative (W/kg) and absolute (Watts) maximal lower body anaerobic power were correlated accordingly with overall pentathlon performance. Third, we analyzed the differences between average performance in national and international competitions. Only the combined running and shooting event out of the five modern pentathlon events showed a difference. Grip strength and relative leg strength—average extensor AP (%BW) appeared to be different among the physical fitness factors. Fourth, we examined the level of contribution of each of the fitness factors on overall performance. The model’s goodness of fit was confirmed, and grip strength was found to have a significant contribution on overall performance. Furthermore, the level of contribution was higher in the following order: relative leg strength—left and right average flexor (%BW), bench press, half squat, relative leg strength— average extensor AP(%BW), GXT—time to exhaustion, relative lower body anaerobic average power (W/kg), and maximal lactic acid concentration. With the 2020 Tokyo Olympics just around the corner, combined running and shooting performance appeared to be a decisive factor in the final ranking in modern pentathlon according to the analysis of the basic and specific fitness factors of pentathletes. The basic fitness factors are critical in order of sergeant jump, grip strength, reaction time, lung capacity, side-step, back strength, 20 m shuttle run, sit-and-reach, sit-ups, and single leg standing. With respect to the specific fitness factors, relative leg strength—left and right average flexor (%BW), bench press, half squat, relative leg strength—average extensor AP (%BW), GXT—time to exhaustion, relative lower body anaerobic average power (W/kg), and maximal lactic acid concentration showed their relevance accordingly. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.1

Attitude Control Strategy for HAUSAT-2 with Pitch Bias Momentum System

The HAUSAT-2 is a 25kg class micro/nanosatellite which is being developed by graduate students at the Space System Research Laboratory(SSRL). This paper addresses a newly proposed strategy for detumbling the HAUSAT-2 and starting up a momentum wheel, and also studies performance validation and application ranges of such method through simulation. B-dot logic is generally used for controlling the initial tip-off rate. However, it has the disadvantage of taking a relatively long time to control the initial tip-off rate. To solve this problem, this paper suggests a new detumbling control method to be able to adapt to micro/nanosatellite with the pitch bias momentum system, and has shown simulation results. Proposed detumbling method was able to control the angular rate within 20 minutes which is a significant reduction compared to conventional methods. In addition, the momentum wheel initial start-up must be done under stable conditions, and conventional pitch spin-stabilized initial wheel start-up method is commonly used. The performance of the method is compared and verified through simulation. The overall result shows much faster control time compared to the conventional methods, and achievement of the nominal wheel speed and 3-axes stabilization while maintaining stability

Neurocutaneous Melanosis Presenting as Chronic Partial Epilepsy

BACKGROUND: Neurocutaneous melanosis (NCM) is a rare neurocutaneous syndrome characterized by the presence of multiple congenital melanocytic nevi (CMN) and the proliferation of melanocytes in the central nervous system, usually involving the leptomeninges. Chronic partial epilepsy as a sole manifestation is rare in NCM. CASE REPORT: A 32-year-old man suffering from chronic partial epilepsy presented with multiple CMN on his trunk and scalp. Brain MRI demonstrated a focal lesion in the right amygdala that was consistent with interictal epileptiform discharges in the right temporal region on electroencephalography (EEG). An anterior temporal lobectomy was performed, and the pathology investigation revealed numerous melanophages in the amygdala. The patient was seizure-free after surgery. CONCLUSIONS: We report a patient with NCM presenting as chronic partial epilepsy who was successfully treated by anterior temporal lobectomy.ope

Elucidation of Akkermansia muciniphila Probiotic Traits Driven by Mucin Depletion

Akkermansia muciniphila is widely considered a next-generation beneficial microbe. This bacterium resides in the mucus layer of its host and regulates intestinal homeostasis and intestinal barrier integrity by affecting host signaling pathways. However, it remains unknown how the expression of genes encoding extracellular proteins is regulated in response to dynamic mucosal environments. In this study, we elucidated the effect of mucin on the gene expression and probiotic traits of A. muciniphila. Transcriptome analysis showed that the genes encoding most mucin-degrading enzymes were significantly upregulated in the presence of mucin. By contrast, most genes involved in glycolysis and energy metabolic pathways were upregulated under mucin-depleted conditions. Interestingly, the absence of mucin resulted in the upregulation of 79 genes encoding secreted protein candidates, including Amuc-1100 as well as members of major protein secretion systems. These transcript level changes were consistent with the fact that administration of A. muciniphila grown under mucin-depleted conditions to high-fat diet-induced diabetic mice reduced obesity and improved intestinal barrier integrity more efficiently than administration of A. muciniphila grown under mucin-containing conditions. In conclusion, mucin content in the growth medium plays a critical role in the improvement by A. muciniphila of high-fat diet-induced obesity, intestinal inflammation, and compromised intestinal barrier integrity related to a decrease in goblet cell density. Our findings suggest the depletion of animal-derived mucin in growth medium as a novel principle for the development of A. muciniphila for human therapeutics

The First Case of X-linked Alpha-thalassemia/Mental Retardation (ATR-X) Syndrome in Korea

Mutation of the ATRX gene leads to X-linked alpha-thalassemia/mental retardation (ATR-X) syndrome and several other X-linked mental retardation syndromes. We report the first case of ATR-X syndrome documented here in Korea. A 32-month-old boy came in with irritability and fever. He showed dysmorphic features, mental retardation and epilepsy, so ATR-X syndrome was considered. Hemoglobin H inclusions in red blood cells supported the diagnosis and genetic studies confirmed it. Mutation analysis for our patient showed a point mutation of thymine to cytosine on the 9th exon in the ATRX gene, indicating that Trp(C), the 220th amino acid, was replaced by Ser(R). Furthermore, we investigated the same mutation in family members, and his mother and two sisters were found to be carriers