• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.449-456
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• 2021

In this paper, we present a strategy to extend solution capability of an existing low Mach number preconditioned compressible solver to incompressible flows with a little modification. To this end, the energy equation that is of the same form of the total energy equation of compressible flows is used. The energy equation is obtained by a linear combination of the thermal energy equation, the continuity equation and the mechanical energy equation. Subsequently, a modified artificial compressibility method in conjunction with a time marching technique is applied to these incompressible governing equations for steady flow solutions. It is found that the Roe average of the common governing equations is equally valid for both the compressible and incompressible flow conditions. The extension of an existing compressible solver to incompressible flows does not affect the original compressible flow analysis. Validity for incompressible flow analysis of the extended solver is examined for various inviscid, laminar and turbulent flows.

• Animal Systematics, Evolution and Diversity
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• v.16 no.2
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• pp.169-176
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• 2000

As one of researches to clarify the taxonomic status of roe deer from Jeju island (C. pygargus tianschanicus), we analyzed partial sequences of mtDNA cytochrome b gene from six roe deers at Jeju island in Korea. Maximum nucleotide Tamura & Nei's distance among three haplotypes was 0.005, and this distance was comparable to the diversity within other roe deer subspecies: it is suggested that roe deers from the mainland dispersed rarely to Jejudo Island, although further analyses are ne-cessary to decide whether or not it was occurred by human introduction. Furthermore, nucleotide distance between cytochrome b sequences of roe deers from Jeju (C. pygargus tianschanicus) and the sequence of roe deer from west Siberia(C. p. pygargus), obtained from GenBank, was average 0.013, and it is suggested that C. p. tianschanicus diverged from C. p. pygargus of west Siberia 0.65 Myr ago.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.387-393
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• 2014

In this study were performed to investigate the physicochemical properties of flying fish roe shell extract(FRSE) extracted from flying fish roe shell. FRSE was prepared using marine flying fish roe shell, and then analyzed it's physicochemical properties. The result showed that the nutritional composition of FRSE consisted of 81.00% protein, 9.12% ash and 4.48% moisture. There were OH-proline and glycine known as characteristics of collagen peptide in the amino acid analysis of FRSE, and there were large amount of glutamic acid and aspartic acid involved in the metabolism of glucose and fat. The calories of FRSE was 347 kcal/100g and molecular weight appeared less than 1,300 Da molecular weight distribution.

• Korean Journal of Agricultural and Forest Meteorology
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• v.14 no.4
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• pp.254-259
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• 2012

Peeling damage of trees is usually caused by Cervidae such as deer, roe deer because of the lack of food in forests. However, it happens as part of the developing of antlers in Jeju Island when the roe deer try to remove the Velvet-the skin of the antlers. The research area is the Hannam experimental forest (400 m up to 500 m above sea level) of Korea Forest Research Institute in Jeju Island, and the survey was carried out along the 6 km long of forest road with 5 m width on both sides. Twenty five tree species (total 267 stands) are damaged by peeling; 18 (134 stands) deciduous broad-leaved species, 5 (71 stands) in evergreen broad-leaved species, 2 (62 stands) coniferous species. The most common damaged species are in order of Daphniphyllum macropodum, Cryptomeria japonica, Lindera erythrocarpa, Clerodendrum trichotomum, Zanthoxylum schinifolium. Mainly damaged trees are approximately 3~4 years old saplings, and they show the mean height $120.7{\pm}42.4cm$, diameter measured at 5 cm height $1.5{\pm}0.5cm$. The Lowest peeling beginning height is $22.1{\pm}10.1cm$, and the mean length of peeling is $27.5{\pm}10.6cm$. Once the peeling damage happens, the saplings are infected by fungi secondly, and are distorted or dead, therefore the future structure of warm-temperate forests could be in influenced in species. Warm-temperate forest landscape and species change related to the climate change is a rising issue in Jeju Island. However the changes caused by peeling damage also could be an important issue in the natural process of forest environment, afforestation, local nursery and sustainable forest management of Jeju Island.

• Journal of Intelligence and Information Systems
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• v.24 no.3
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• pp.157-176
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• 2018

The purpose of this research is to develop a detection model for companies designated as administrative issue in KOSDAQ market using financial data. Administration issue designates the companies with high potential for delisting, which gives them time to overcome the reasons for the delisting under certain restrictions of the Korean stock market. It acts as an alarm to inform investors and market participants of which companies are likely to be delisted and warns them to make safe investments. Despite this importance, there are relatively few studies on administration issues prediction model in comparison with the lots of studies on bankruptcy prediction model. Therefore, this study develops and verifies the detection model of the companies designated as administrative issue using financial data of KOSDAQ companies. In this study, logistic regression and decision tree are proposed as the data mining models for detecting administrative issues. According to the results of the analysis, the logistic regression model predicted the companies designated as administrative issue using three variables - ROE(Earnings before tax), Cash flows/Shareholder's equity, and Asset turnover ratio, and its overall accuracy was 86% for the validation dataset. The decision tree (Classification and Regression Trees, CART) model applied the classification rules using Cash flows/Total assets and ROA(Net income), and the overall accuracy reached 87%. Implications of the financial indictors selected in our logistic regression and decision tree models are as follows. First, ROE(Earnings before tax) in the logistic detection model shows the profit and loss of the business segment that will continue without including the revenue and expenses of the discontinued business. Therefore, the weakening of the variable means that the competitiveness of the core business is weakened. If a large part of the profits is generated from one-off profit, it is very likely that the deterioration of business management is further intensified. As the ROE of a KOSDAQ company decreases significantly, it is highly likely that the company can be delisted. Second, cash flows to shareholder's equity represents that the firm's ability to generate cash flow under the condition that the financial condition of the subsidiary company is excluded. In other words, the weakening of the management capacity of the parent company, excluding the subsidiary's competence, can be a main reason for the increase of the possibility of administrative issue designation. Third, low asset turnover ratio means that current assets and non-current assets are ineffectively used by corporation, or that asset investment by corporation is excessive. If the asset turnover ratio of a KOSDAQ-listed company decreases, it is necessary to examine in detail corporate activities from various perspectives such as weakening sales or increasing or decreasing inventories of company. Cash flow / total assets, a variable selected by the decision tree detection model, is a key indicator of the company's cash condition and its ability to generate cash from operating activities. Cash flow indicates whether a firm can perform its main activities(maintaining its operating ability, repaying debts, paying dividends and making new investments) without relying on external financial resources. Therefore, if the index of the variable is negative(-), it indicates the possibility that a company has serious problems in business activities. If the cash flow from operating activities of a specific company is smaller than the net profit, it means that the net profit has not been cashed, indicating that there is a serious problem in managing the trade receivables and inventory assets of the company. Therefore, it can be understood that as the cash flows / total assets decrease, the probability of administrative issue designation and the probability of delisting are increased. In summary, the logistic regression-based detection model in this study was found to be affected by the company's financial activities including ROE(Earnings before tax). However, decision tree-based detection model predicts the designation based on the cash flows of the company.

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.213-222
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• 2018

This study attempts to empirically investigate the excess returns of growth stocks in the Korean stock market comparing with those of value stocks. Recently, a few of IT and bio-pharmaceutical stocks with high growth potentials have accomplished dramatically high returns in the Korean stock market. Whereas, important prior studies in this line have observed negative excess returns from investment of growth stocks on average. And a few studies have reported that the distribution of excess returns from growth stocks is not normal but positively skewed. Empirical results of the present study are consistent with those of prior studies. Interestingly, the present study observed serial inverse correlation between excess returns of growth stocks and value stocks. Also, regardless of growth or value stocks, the stocks with higher PEG(=PER/ROE) showed higher excess returns.

• Korea Trade Review
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• v.41 no.1
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• pp.67-90
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• 2016

This study examines whether there is any significant relation between executive compensation and future firm performance for the Korean export manufacturing small and medium-sized firms. We sorted the whole sample firms into the sub-groups of 10 deciles by firm size and the KSIC standard. We found the following empirical results. First, Korean export manufacturing small and medium-sized firms typically showed lower or even negative profitability in terms of return on equity and operating profit ratio to sales. Foreign equity ownership is very low with an average of 3.77%. Second, for the firms with higher ratio of excess executive compensation to asset had lower future firm performance. It implies that the typical owner-manager in Korean export manufacturing SMEs earns excess pay, but do not contribute much to firm performance. Third, as for future cumulative abnormal returns for future one- and three-year periods, firms with higher owner-executive pay had lower returns compared with firms with lower pay. So the stock market investors set a lower value on them. Fourth, there is a positive relation between excess executive pay and executive overconfidence, and it implies that owner-CEOs with higher pay may become overconfident, thereby lowering future firm performance somehow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.9
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• pp.1075-1080
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• 2004

In this study, performance and emissions characteristics of an liquefied petroleum gas (LPG) engine converted from a diesel engine were examined by using mixer system and liquid propane injection (LPi) system fuel supply methods. A compression ratio for the base diesel engine, 21, was modified into 8, 8.5, 9 and 9.5. The cylinder head and the piston crown were modified to roe the LPG in the engine. Ignition timing was controlled to be at minimum spark advance for best torque (MBT) each case. Engine performance and emissions characteristics are analyzed by investigating engine power, brake mean effective pressure (BMEP), brake specific fuel consumption (BSFC), volumetric efficiency, CO, THC and NOx. Experimental results showed that the LPi system generates higher power and lower emissions than the conventional mixer fuel supply method.

• The Korean Journal of Financial Studies
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• v.11 no.1
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• pp.177-198
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• 2005

본 연구는 기업의 자본비용을 반영한 초과이익(excessive earnings)의 우리나라 주식시장에서 투자지표로서의 유용성에 대해서 분석하였다. 이를 위해서 주당초과이익과 함께 전통적인 성과지표인 주당순이익을 비교분석하였으며, 주된 분석결과를 요약하면 다음과 같다. 첫째, 분석기간 중 주당순이익을 기준으로 보면 대부분의 기업들이 양(+)의 값을 가지는 것으로 나타났으나, 주당초과이익의 경우에는 대다수의 기업들에서 음(-)의 값을 가지는 것으로 나타났다. 이는 기업들이 주주들에게 충분한 보상을 하지 못하고 있다는 것을 의미한다. 둘째, 주당초과이익(EES)은 전통적인 성과지표(EPS, ROE)보다 주식수익률과 상관관계가 높으며, 주당순이익에 비하여 주당초과이익을 기준으로 포트폴리오를 구성하는 경우에 보다 높은 초과수익률을 올릴 수 있는 것으로 나타났다. 셋째, 주당순이익 기준에 의한 하위집단의 누적평균초과수익률은 유의적으로 음의 값을 보이는 반면에 상위집단은 0과 차이를 보이지 않는다. 그러나 주당초과이익 상위집단의 수익률은 시장수익률보다 유의하게 높고 하위집단에서는 낮게 나타난다. 이는 주당순이익이 낮은 EPS 하위집단의 경우는 당기순손실이 주는 부정적 효과가 반영된 것으로 유추할 수 있으며, 투자지표로서는 EES가 유용한 것으로 판단된다. 결론적으로 기업의 진정한 부가가치 생산은 자본비용을 반영한 순이익이며, 제한적이지만 우리나라 주식시장에서 초과이익이 투자지표로서 활용될 수 있을 것으로 판단된다.

• Journal of the Korean Geographical Society
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• v.41 no.6 s.117
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• pp.657-669
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• 2006

Rates and processes of bare patch denudation were observed at Janggumokoreum(1,710m) and Minoruem(1,600m) in order to clarify some characteristics of turf exfoliation in the subalpine grassland of Mt. Halla. The bare patches have marginal terrace fronts with a maximum height of 85 cm. The terrace risers usually develop an overhanging edge 2 to 38 cm long that eventually hangs down and protects the riser beneath. The patches are largely covered with angular pebbles and cobbles. The mean rate of riser retreat for the period 2002-2004 is 39.2 mm, equivalent to 19.6 mm/yr. However, there is a disparity of the rate of riser retreat at individual sites. The maximum rate is 131 mm measured at Janggumokoreum patch while the minimum rate is 0 mm at Minoreum patch. The rate of riser retreat also varies with seasons. The thawing season of April exhibits a maximum rate of retreat. The freezing season of October and November and the rainy season of June and July show relatively high rates of retreat. Several Processes such as frost action, aeolian deflation, rainwash, rainsplash and fauna activity cause the denudation of bare patches. In particular, the needle ire action which is combined with rainwash or deflation plays a primary role in turf exfoliation due to the diurnal freeze-thaw cycles occurred over 100 days, melted snow and strong wind in the subalpine zone of Mt. Halla. Rainwash is also an important contributing process in the rainy season because Mt. Halla has the highest precipitation in Korea. By contrast, rainsplash erosion has a minor effect on the bare patch denudation due to the overhanging edge of terrace risers. Recent increase in roe deer appears to be responsible for turf destruction.