• Korean Journal of Environmental Biology
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• v.33 no.4
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• pp.403-411
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• 2015

To understand differences of environmental factors and planktonic communities in closed (CS) versus open (OS) enclosed experimental systems, we performed a study on a 100-L indoor-type artificial marine microcosm. For environmental factors, including water temperature, dissolved inorganic phosphorus, and dissolved silica, there were no significant differences between CS and OS; however, salinity was higher in CS than that of OS due to the evaporation effect. The concentration of dissolved oxygen and dissolved inorganic nitrogen was lower in CS than in OS. The abundance of phytoplankton was lower in CS than in OS. However, abundance of autotrophic nanoflagellates and heterotrophic bacteria varied inversely with that of phytoplankton abundances. In particular, the abundance of heterotrophic nanoflagellates and ciliates increased with bacterial growth after a time lag. Therefore, environmental factors and planktonic communities in CS gradually changed over time and characterized a different artificial ecosystem than in OS.

• Fire Science and Engineering
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• v.25 no.2
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• pp.132-137
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• 2011

A relationship between resisting moment and the structure of an automatic closure device is introduced for analyzing the effect of opening and closing condition on various fire door sizes in the pressurized room for smoke control system. The larger the size of fire door is, the more force is required for reaching to opening and closing conditions and there exists the design range of fire door in the pressurized room reflecting the closing time of fire door, rotative velocity, a relation between rotative angle and force and the efficiency of the automatic closure device.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.2023-2027
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• 2009

본 연구는 현재와 과거의 하도 지형자료 분석을 통하여 만경강에서 나타나는 폐천(Abandoned channel)을 파악하고, 유형을 폐쇄형, 개방형, 육화형 폐천으로 구분하여 각각의 본류구간과 함께 식물상 및 식생분포 특성을 비교하였다. 만경강의 경우 1918년 하도 형태가 경지정리 및 치수사업에 따른 제방축조 등 인위적인 절단(Engineered cutoff)으로 8개소 이상의 구간에서 하도 선형이 크게 변경됨으로써 폐천이 형성되는 것으로 나타났다. 현재 폐천부지는 육화형태의 농지 이용 및 개방형 또는 폐쇄형의 습지로 유지되는 것으로 조사되었다. 폐천 유형에 따라 나타난 식물상은 폐쇄형 56종류, 개방형 31종류로 조사되었다. 육화형의 본류의 경우 보에 의한 영향으로 달뿌리풀 (Phragmites japonica)과 저수로 검정말(Hydrilla verticillata) 등의 수생식물이 우점하는 정체수역이 나타났다. 개방형 폐천은 갈수기에도 수심이 깊은 수역이 확보되어 본류에 비하여 출현종수가 높았다. 폐쇄형 폐천은 연꽃(Nelumbo nucifera), 애기부들(Typha angustifolia) 등의 다양한 수생식물이 출현하여 본류에 비해 안정된 습지 생태계를 유지하였다. 만경강의 개방형과 폐쇄형 폐천은 수생식물의 증가와 전형적인 습지생태계를 유지하고 있었으며 본류의 정체수역이 관찰되었다. 본래 하천의 연속성을 향상하기 위한 유수생태계의 복원은 하천의 건강성을 향상하기 위한 방안이 될 것이다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.12-16
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• 2010

본 연구에서는 건설현장의 특별 피난계단 출입문 크기와 구조의 다양성을 고려한 자동폐쇄장치의 설계방안을 제시하였다. 이를 위해서 급기가압실의 방연풍속, 누설량 그리고 송풍기의 용량이 일정한 경우 출입문이 폐쇄되기 위한 힘의 상관관계를 회전각도와 회전속도의 변화에 따라서 분석하였으며, 방화문의 폭이 1,100 mm, 1,300 mm 인 경우 각각에 대해서 개방력과 폐쇄력을 측정하였다. 그 결과 현장 조건을 만족할 수 있는 자동폐쇄장치에 의한 방화문의 폐쇄조건 및 회전각도와 회전속도의 변화를 고려한 개방력과 폐쇄력의 최적 설계범위가 존재함을 확인하였다.

• Survey Research
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• v.18 no.4
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• pp.127-147
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• 2017

Despite the importance of questionnaires, little survey methodology research on questionnaire design has been conducted in Korea. The purpose of this study was to explore whether two questionnaire forms (close-ended vs. open-ended questions) about 'the most important problem in Korea' elicited similar responses. During the 2016 Korean General Social Survey (KGSS), a random half of respondents were asked the open-ended question form and the remaining half were asked the close-ended question form. While the economy is the most mentioned response (35% vs. 33.2%) to both close-ended and open-ended question forms, there is similarity in the order of highly mentioned responses if we consider that 'politics' is not provided as one of response categories in the close-ended question form. The order of second to fourth response category is crime (24.4%), education (15.4%), and poverty (6.3%) to the closed-ended question form, and politics (10.8%), crime (9.5%), and education (7.6%) to the open-ended question form. Also, the characteristics of respondents who responded with the economy as being the most important are slightly different between the two halves in terms of age, household income, and satisfaction with economic condition. Our findings suggest that we need to be careful when we adopt questions developed in other countries and to consider using survey experiments in pre-testing questionnaire items.

• Solar Energy
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• v.7 no.1
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• pp.42-52
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• 1987

파형 단면을 가진 유하식 집열기의 이론 및 실험 결과로서 유량, 각도등 집열성능에 미치는 영향등이 고려되었다. 입구 온도와 출구온도 차이가 적을 경우에는 이론과 실험치가 잘 맞으나 온도차이가 많을 경우 혹은 입구온도가 높을 때에는 투과체안에 생기는 결로 및 수증기의 영향으로 편차가 커진다. 개방회로와 폐쇄회로의 경우를 구분하여 실험되었는데 개방회로의 경우 효율은 약간 저하되지만 전반적인 성능은 폐쇄회로와 같은 경향을 나타내었다. 개방회로는 과열을 막는 방편으로 이용될 수 있다.

• Journal of Chest Surgery
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• v.40 no.11
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• pp.765-769
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• 2007

Background: The curative treatment of choice for empyema is decortication of the pleura. The risks of this treatment however are increased for the patient with reduced pulmonary function, complicated calcification or septic shock. In the past, open window thoracostomy was a final stage treatment for chronic empyema. Relatively safe treatment of empyema could be achieved in difficult cases with a closure of the open window after open drainage and use of a myocutaneous flap (one stage or staged). Material and Method: A retrospective study of the cause, progression and final outcome of empyema patients who received open window thoracostomy was performed. 21 patients were followed from 1995 to 2004 in the department of Thoracic and Cardiovascular Surgery in the College of Medicine, Pusan National University. Result: The average age of the patients was $57.5{\pm}15.5$ years (range $25{\sim}78$ years), of whom 16 (76.2%) were men and five (23.8%) were women. Pulmonary function test results showed an average FEV1 of $1.58{\pm}0.49 L$. The type of empyema was tuberculous empyema in 13 cases (61.9%), aspergillosis in three cases (14.3%), parapneumonic empyema in three cases (14.3%) and post-resectional empyema in two cases (10%). Bronchopulmonary fistula was seen in 14 cases. Eight cases were complicated by severe calcification of the pleura. For the four cases of bronchopulmonary fistula, the patients' serratus anterior muscle was covered in their first operation. The average number of ribs resected was $4{\pm}1$. Closure of the open window thoracostomy was performed in 12 cases. The average time to closure after open drainage was $10.22{\pm}3.11$ months and the average defect of the empyemal cavity before the final operation was $330{\pm}110 cc$. Among the 12 cases, there were two cases of spontaneous closure. In two cases closure was only achieved by using the reserved skin fold during the first surgery. Of the remaining eight cases, in seven we used the myocutaneous flap (four cases of lattisimus dorsi muscle and three cases of pectoralis major muscle), and in one case we used soft tissue. As regards complications of the closure, tissue necrosis occurred in one case, which led to failed closure, and there was one case of abdominal hernia in the rectus abdominis muscle flap. One patient died within 30 days of the surgery and one patient died of metastatic cancer. Conclusion: A staged operation with a final closure using open window thoracostomy, which consists of open drainage, transposition of the muscle and a myocutaneous flap, can be a safe and effective option for the chronic empyema patient who is difficult to cure with traditional surgical methods.

• KDI Journal of Economic Policy
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• v.36 no.1
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• pp.81-106
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• 2014

This paper compares the monetary policy problem in open economies with that in closed economies. It is found that the monetary policy problems in open and closed economies are isomorphic even in the presence of distortions in a steady state and hence the optimal monetary policies have similar properties. On the other hand, the monetary policy maker in open economies has a distorted incentive to manipulate the terms-of-trade. Because of the additional distortion in open economies, there exist gains from international monetary policy cooperation even in the case of a unit intertemporal elasticity of substitution, in contrast to the literature that abstracts from distortions in a steady state. Also, it is found that in the presence of distortions inflation bias is decreasing in openness, which is line with empirical evidence. In addition, this paper presents a simple transformation so that methods in closed-economy models are easily applicable to open-economy models.

• Information Systems Review
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• v.16 no.3
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• pp.135-160
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• 2014

Most Social Network Service (SNS) provide online chat, video and file sharing, blogging and others. Because of this advantage, people depend on SNS to communicate with others. However, recently SNS encourage people to reveal too much information broadly so SNS users are concerned about privacy invasion and data spill. They also feel fatigue in process of touching people they don't know while using SNSs. That is the reason why they attempt to switch from opened SNS to Closed SNS. Therefore, the purpose of this study is to empirically investigate and analyze the effect of the factors on the SNS users' switching behavior when using SNS. To accomplish this purpose, this research adopted "Push-Pull-Mooring (PPM)" framework. The PPM is proposed by population geologist, who used it to explain the incentives of demographic migration. Following PPM model, this research empirically examines the three categories of antecedents for SNS switching intention toward closed SNS: push (i.e., weak connection, privacy concern, relative complexity), pull (i.e., enjoyment, belongingness, peer influence), mooring (i.e., SNS fatigue, user resistance) factors. The survey was conducted for 285 users on SNS communities in Korea. The results of this study are as follows; First, wear connection and privacy concern are significantly related to SNS switching intention. Second, enjoyment and belongingness are significantly related to SNS switching intention. Finally, the results show that SNS fatigue has a moderating effect on the links between push factors and SNS switching Intention. Also, user resistance has a moderating effect on the links between pull factors and SNS switching Intention. These findings contribute to the SNS literature both theoretically and practically.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.101-109
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• 2007

Two variations of toll roads exist: mainline toll plazas and entry/exit tolls. On a mainline toll system(open toll scheme), all vehicles stop at various locations along the highway to pay a toll. While this may save money from the lack of need to construct tolls at every exit, it can cause lots of traffic congestion, and drivers could evade tolls by going around them. With entry/exit tolls, vehicles collect a ticket when entering the highway, which displays the fares it will pay when it exits, increasing in cost for distance travelled. Upon exit, the driver will pay the amount listed for the given exit. The pressures on the Seoul ring roadway network have been changing over time. In the past, the emphasis was on mobility and maintenance of the road network to provide an efficient transportation network, but recently, road use has outstripped the network's ability to extend and expand the road network and hence the policy emphasis has moved towards reducing free riders rather than mitigating its effects. In addition to this pressure is an incidental pressure, which argues that provision of free ride segments generates further traffic in isolation of other factors. This paper is examining policies to reduce the burden of traffic congestion in Seoul ring roadway which is used open toll scheme for decades. One key mechanism to achieve this policy aim is automatic charging mechanism on freeway, but if a nation-wide electronic toll collection is to be implemented successfully, there are a number of prerequisites which must be place.