Byung-Yeon Kim

Optimization of environmental factors for the production and handling of recombinant retrovirus

Certain steps from the production to infection of the amphotrophic retroviral vector, MFG-LacZ, were optimized and the factors that affect retroviral titers were analyzed. Retroviral vector titers were highest when the culture supernatant was harvested 3 days after the producer cells had reached confluence. About a 2-fold increase in vector production was achieved at 32°C compared to that at 37°C. Low serum concentrations had no significant effect on the titers of virus produced by the CRIP cell line. Retroviral vectors were stable at 4°C but very unstable at 37°C and were quite sensitive to freezing and thawing. About 30%–50% of viral infectivity was lost during the thawing step and the loss was not recovered by the addition of commonly used cryoprotectants. Increase in viral exposure time for infection to target NIH3T3 cells was linearly proportional to the retroviral titer for up to 15 h. In addition, using DEAE-dextran in place of polybrene as a polycation during infection enhanced infection efficiency about 3-fold. The retrovirus was robust to simple ultrafiltration and its titer could be easily concentrated 16-fold. Taken together, our data suggest that at least a 100-fold increase in titer can be achieved with simple optimization.

The Informal Economy and the Growth of Small Enterprises in Russia

This article uses Russian regional data to estimate the determinants of the informal economy and to examine the relationship between the informal economy and the growth of legally registered small private enterprises during the transition period. After obtaining an estimate of the size of the informal economy in each Russian region from 1992 to 1999, an analysis is performed to find whether reform progress and institutional qualities account for the informal economy. An evaluation of the links between the informal economy and the growth of small enterprises within Russia is then carried out. The findings suggest that Russias informal economy resulted from a delay in reform and low qualities of institutions. It was found that the growth of small enterprises is positively affected by the informal economy. These results imply that the informal economy helped entrepreneurial activities to grow in the face of government failure, but these informal activities tend to become official over time.

Determinants of Labor Market Participation and Wages of North Korean Female Refugees in South Korea

This paper uses data from a survey on 289 North Korean female refugees who arrived in South Korea in 2007 to understand the determinants of their economic adaption in the South Korean labor market. More specifically, we look at the effects of job finding channels and government policies on the labor market participation and wages of these women. We find that job finding through both personal contacts and public employment networks increases the probability of finding employment, but the former, especially job finding through contacts with South Koreans, is the most effective route to finding employment. In addition, jobs with higher wages are acquired in employment attained from South Korean referrals, followed by South Korean government agencies and those from North Korean refugee contacts. We further find that labor market participation is negatively affected by both public benefits and private transfers possibly because of increases in the reservation wages of job seekers.

The Informal Economy and Bribery in North Korea

This paper uses the data of 227 North Korean refugees who have settled in South Korea to investigate the relationship between working in the informal economy (market component of the economy) and bribe-giving, and between bribe-giving and the number of hours worked in the formal sector (planned component of the economy). The first relationship is positive, and the second relationship is negative. These results imply that widespread informal economy activities in North Korea have been undermining the socialist regime through bribery.

The Possibility of Economic Reform in North Korea

Abstract This article argues that North Korea can achieve an economic catch-up after decades of economic isolation and stagnation by promoting an economic opening focused on foreign trade and investment in a sustained manner. An analogy is been made with the case of Fujian Province in China, which has accomplished economic catch-up, mainly due to Taiwanese investments. To realise its potential, it is argued that North Korea treats its foreign direct investment (FDI) from South Korea as intra-Korean investment. The article also discusses the diverse modes of engagement with foreign capital that are available for North Korea, considering its own capability (absorption or management capabilities), rivalry among possible foreign investors, implications for market structure (monopoly or more competition), the nature of target technologies or facilities, opportunity for learning and transfer, and so forth. Finally, the article discusses the economic and political preconditions for such and economic catch-up.

Financial Systems and Enterprise Restructuring in Eastern Europe

This article investigates the effects of financial systems on enterprise restructuring in twenty-six transition economies from 1999 to 2005. It identifies various sources of financing and estimates their respective impacts on enterprise restructuring. Loans from local commercial banks are found to be more effective than any other form of financing at promoting restructuring. Their effect increases as the size of the firm decreases. There is some evidence that the effectiveness of equity financing in restructuring increases over time, suggesting that the equity mechanism takes root in transition economies only gradually. It is also found that restructuring contributes to firm performance, suggesting a linkage among financing sources, restructuring, and firm performance.

Scenarios for a Transition to a Prosperous Market Economy in North Korea

We examine in detail two possible scenarios for a transition to the market economy in North Korea. In the first scenario, we explore a transition path of North Korea to the market economy following a regime collapse. In the second scenario, we explore a transition path that would be chosen by the North Korean leaders, following the experience of China and Vietnam. While these scenarios have common features, they also involve important differences.

P29.07: Short-term and long-term outcome of spontaneous twin anemia-polycythemia sequence

A higher prevalence has been reported in pregnancies complicated by selective growth restriction (sFGR), birth weight discordance (BWD). We aimed to investigate the association between cord insertion site and adverse pregnancy outcomes in twin pregnancies. Methods: A single-centre cohort study of twin pregnancies that had placental histology. Higher-order multiples, major fetal anomaly, aneuploidy and MCMA pregnancies were excluded. Cord insertion site was categorised into 3 groups: marginal (attachment <2cm to the placental margin), velamentous (attached to the membrane before reaching the placenta with vessels traversing the membranes), normal. Chorionicity, placental weight, number of cord vessels, examination of the membranes, ultrasound findings, maternal characteristics and pregnancy outcome were collected. Results: 546 pregnancies were eligible; 497 (146 monochorionic; 351 dichorionic) were included in the analysis. Significant differences were found between the normal and abnormal cord insertion groups with regards to BWD (P=0.001), BWD>25% (P=0.001), and absolute Z-score differences (P=0.020). Velamentous, but not marginal, cord insertion was significantly associated with sFGR (OR 8.51,95%CI 2.09-34.58;P=0.03) and BWD>25% (OR 11.88,95%CI 3.54-39.79;P=0.04). In MCDA, but not DCDA pregnancies, the rate of composite adverse outcome was higher in those with abnormal cord insertion (70.0% vs 53.0%, p=0.04). Conclusions: Selective fetal growth restriction and birthweight discordance are more common in twin pregnancies with abnormal cord insertion. MCDA twins with velamentous cord insertion are at increased risk of sFGR, and composite adverse pregnancy outcome.

South and North Korea: Economic Challenges and Policy Issues

This special symposium section consists of seven papers on South and North Korea. The four papers on South Korea are the results of a research project of the Social Science Korea program titled “Search for a New Framework in the Analysis of the Korean Economy: Based on a New Perspective about EmergingMarket Countries.” They investigate exchange rate behaviors and monetary and macroprudential policies in South Korea. Exchange rate behaviors have been one of the most crucial economic issues in Korea, since Korea is much integrated to the world economy in terms of financial and goods/services markets.Monetary policy has been an important traditional macroeconomic policy in many countries including Korea. Korea has been one of the most frequent users of macroprudential policy (such as the ratios of loan-to-value (LTV) and debt-to-income (DTI)), which has receives a great amount of attention after the global financial crisis. These works were supported by the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2014S1A3A2044637). In the first article, Yun provides a noble perspective on the purchasing power parity puzzle. The notion of the purchasing power parity has been an important building block for many theoretic models in international economics. However, past studies often documented that the deviation from the purchasing power parity is too persistent to be justified by popular theoretical models, which is known as the purchasing power parity puzzle. The article suggests that the slow adjustment of the natural exchange rate is mainly responsible for the puzzle. The author empirically examines the relative importance between the financial and output gap channels in explaining the puzzle, and finds that the financial channel is a dominant factor to explain persistent deviations of the real exchange rate from its long-run level. In the second article, Jung, Kim, and Yang investigate the effects of macroprudential policy in Korea, both empirically and theoretically. Empirical results based on vector auto-regression (VAR) models show that macroprudential policies like LTV and DTI have significant and persistent effect on real household credit and real house price in South Korea. They further examine the implications of optimal macroprudential and monetary policy by employing a standard dynamic stochastic general equilibrium model. The results suggest that the time-varying macroprudential policy responding to the borrower’s debt to income ratio is most effective in stabilizing household debt among the macroprudential policy rules considered, although such a policy produces a moderate downturn of the economy. In the third article, Lee empirically investigates the relationship between exchange rate and firm investment considering two possible channels, namely exports and imports, in South Korea. By employing a firm-level panel dataset based on the Census on Establishments, she examines how the exchange rate level or exchange rate changes affect firms’ activities. The empirical results show that they do not affect exports significantly, as opposed to the conventional wisdom. However, they do affect imports significantly, which may suggest that currency appreciation may not necessarily decrease a firm’s investment level.

Trade Between North Korea and China: Firm-Level Analysis

ABSTRACT Using the unique survey data involving 138 Chinese firms, this study examines the determinants of the performance of the Chinese firms doing businesses with North Korea. The business ties between the Chinese firms and their North Korean counterparts affiliated with the army are positively correlated with the former’s performance. This finding suggests that North Korea’s “Military First” policy acts as a guiding principle of the resource allocation in the country’s export sector. We also found that South Korean sanctions against North Korea were ineffective in banning North Korean goods from gaining access to the South Korean market possibly because of the circumvention of Chinese firms.