A peer assessment method was implemented as part of an action research project where the primary goal was to create constructivist science classrooms. Student reflective writings, which had been created in the process of action research, were analyzed to examine the perceptions of the students concerning the peer assessment method employed in their earth science classrooms. Five perception categories and thirteen statements were developed from the student writings. These indicated that the students appreciated the positive nature of peer assessment and the effects of it as an alternative method for promoting learning. It was also revealed, however, that some students displayed inappropriate behaviors toward peer assessment which led to negative perceptions of the new assessment method. Implications for future use of peer assessment in science classrooms are discussed. Limitations founded in the present study as well as possible solutions are provided.

Labor required for managing and harvesting the oyster mushroom bed was evaluated. Although vinyl mulching cultivation method needs more hours for spawning, it saves more than 50% of labor for harvesting and managing of the mushroom bed. Harvesting hour of 1st-3rd flush in vinyl mulching method was 48~50% for Plerutus ostreatus and 36~41% for P. sajor-caju. Labor for bed management after harvesting in vinyl mulching method was also 38~50% for P. ostreatus compared to conventional method, and 20~35% for P. sajor-caju. Vinyl mulching is believed to be a very efficient method for saving labor in oyster mushroom cultivation.

Structural changes of high modulus carbon fiber by oxidation in carbon dioxide gas using SEM, TEM, and XRD have been observed. It was shown that the originally high modulus carbon fiber is composed of highly ordered graphitic crystalline area and non-crystalline area. It was observed that the La increases during the whole oxidation process. It was shown that the oxidation of high modulus carbon fiber initiates at the non-crystalline area and at the ends of fiber. The large pores developed in fiber by direction of fiber length at high temperature (1,100℃), and the small pores developed on the fiber surface at low temperature (900℃). In conclusion, it is found that the oxidation of the carbon fiber was progressed through the imperfection.

New electroluminescent materials based on anthracene chromophore with naphthylethenyl substituent, 9,10-bis(α-naphthylethenyl)anthracene (a-BNA), as well as four kinds of its derivatives were synthesized, and luminescent properties of these materials were investigated. Electrolumineecent(EL) emission band was discussed based on their substituent structure differences. It was found that the emission band strongly depends on the molecular structure of introduced substituent. It can be tuned from 557 nm to 591 nm by changing the substituent structures. On the other hand, the anthracene chromophore with bulky substituent possessed high melting point and they gave stable films through vacuum-sublimation. The double layer EL device of ITO/TPD/emission layer/Mg:Ag was employed, and exhibited efficient orange light originating from emitting materials. EL emission with a maximum luminance was observed in the b-BNA emitting material, : maximum luminance was about 8,060 cd m-2 at an applied voltage of 10 V and current density of 680 mA/cm2. In conclusion, the electroluminescent properties also showed good difference with their substituent structure.

Polyeyclic aromatic hydrocarbons (PAHs) were quantitatively determined in bivalves from Gwangyang Bay. Twenty-four kinds of target PAHs were detected in the entire samples. Total PAHs concentrations ranged 86.1∼1,210 ng g-1/ dry weight with a average

Tributyltin (TBT) and its degradation products, dibutyltin (DBT) and monobutyltin (MBT) were quantitatively determined in surface sediments and two molluscan species, Pacific oyster (Crassostrea gigas) and rock shell (Thais ctavigera), from Gwangyang Bay,

The first sentence in the second paragraph of INTRODUCTION, 'The first discovery of a galaxy beyond z=5 was reported by Weymann et al. (1998); HDF 4-470.3 at z=5.60.' should be read as 'The first discovery of a galaxy beyond z=5 was reported by Dey et al. (1998); 0140+326 RD1 at z=5.34'. The authors sincerely regret this error.

Most radio astronomy issues at WRC-03 (World Radiocommunication Conference-03) revolved around satellite downlink allocations, particularly to NGSO (Non-Geostationary Satellite Orbit) satellite systems, in bands adjacent to or close to a radio astronomy frequency band. Out of a total of 50 agenda items, ten were of interest to radio astronomers. This paper provides some details about the important outcome of the radio astronomy related issues at the WRC-03.

이 논문은 20세기 후반 건축을 선두로 문학, 미술, 철학등 각 예술 분야에 대두된 포스트모더니즘의 미학을 중심으로 동양 현대음악의 시간적 구조를 살펴본 연구이다. 음악에 있어서 포스트모더니즘은 르네상스 이후 서양음악의 불문율로 여겨왔던 "목적 지향적 시간론(goal-oriented notion of time)"을 파기하고, 새로운 시간개념의 도입을 가능케 한 중요한 논리적 배경이 되었다. 특히 동양적 에토스(ethos)에 근거한 동양 현대 작곡가들의 작품들은 흔히 서양적 관점에서 보면 "목적 지향적 시간구조"의 결여로 이해되어져, 서양 예술론을 적용하기보다는 "이국적 정서(exoticism)" 혹은 "오리엔탈리즘"으로 이해되어져 왔다. 그러나 이 새로운 음악적 시간개념은 동-서양 현대작곡가의 작품을 하나의 통일된 예술론으로 이해할 수 있는 중요한 인식변화를 가져왔다. 이 논문을 통하여 필자는 포스트모던 건축학자 로보트 스턴(Robert Stern)의 "전통적 (Traditional) 포스트모더니즘과 분리파적(Schismatic) 포스트모더니즘론," 레오날드 마이어의 "비목적론적 시간론(NOn-teleology)"등을 바탕으로 포스트모더니즘의 한 시간적 특성을 "시간의 해방(the Emancipation of time)"으로 정의하였다. 한편, 동양철학이나 예술에 나타난 시간적 구조는 "순화적 시간(Circular Time)"과 "초월적 시간(Transcendental Time)"으로 구분 짓고, 그 들의 이중적 혹은 다중적 사용-시간의 이중성(Double Perception of Time)을 서양 포스트모더니즘 시간 구조와 비교, 고찰하였다. 필자는 이 논제를 위하여 일본의 도-루 타케미츠(Toru Takemitsu), 한국의 필자 자신, 중국의 탄 둔(Tan Dun)등 극동의 세 작곡가를 선택하여, 그들 작품에 나타난 음악적 시간구조를 분석하였다. 즉, 이 세 동양작곡가들 작품에 나타난 시간적 특성을 중심으로 그들의 창작과정이나 작품, 음악어법 등을 포스트모니즘이라는 새로운 시각으로 재조명하였다.

The spatio-temporal distribution of four coexisting acartiid species in two subgenera Acartiura (Acartia hongi and A. omorii) and Odontacartia (A. erythraea and A. pacifica) was examined at seven stations in the southwestern waters of Korea, between Janua

The spatial distribution and composition of the mesozooplankton community in the southeastern Barents Sea were observed at 17 stations, from 12 to 28 July 2002. Six taxa of zooplankton were found, including tintinnids, copepods, cumaceans, appendicularian

The southern rough shrimp Trachysalambria curvirostris (Stimpson) was monthly sampled from the coastal area of Yeosu, Korea from June 2000 to May 2001 and its stomach contents were investigated. Mysids and amphipods were the most dominant prey, comprising

Two types of carbon fiber based high modulus- and isotropic-pitch were exposed to isothermal oxidation in air and CO2 gas and the weight change was measured by TGA apparatus. The kinetic equation was introduced f=1--(-atb) and the constant b was obtained in the range of 1.02~1.68 for the isotropic fiber and obtained 0.91~1.93 for the high modulus fiber respectively. In considering the effect of the atmosphere for isothermal oxidation, the value of the constant b obtained in the carbon dioxide was higher than that obtained in the air. Therefore, it was found that the pitch based carbon fiber shows sigmoidal characteristic when it is oxidized in the carbon dioxide. In addition, it was also found that kf = 0.5, which was reaction constant at f = 0.5, was a very useful parameter for evaluation of the oxidation reactivity of pitch based carbon fibers. According to the consideration, it is suggested that the conversion-time curves of the pitch based carbon fibers are correlated by normalized equation f=1--(-AτB), where τ=t/tf= 0.5.

The role of KOH in the one-stage KOH-activation of rice straws was studied using FTIR, XPS, TGA, and DTG techniques.It was found that at the impregnation, KOH extracts to some extent the lignin component from rice straw and reacts withhydroxyl groups. On heat-treatment, the impregnated KOH facilitates intermolecular condensation reaction on one hand butretards the thermal degradation of cellulose molecules on the other hand. The oxygen-containing surface functional groupsnewly created by oxidation of KOH may facilitate the bulk, not controlled, consumption of carbon atoms so that the effectiveporosities may not be able to be developed by the one-stage activation process.

As in other areas of materials technology, the tendency towards light weight constructions becomes more and more important also for powder metallurgy. The development is mainly driven by the automotive industry looking for mass reduction of vehicles as a major factor for fuel economy. Powder metallurgy has to offer a number of interesting areas including the development of sintered materials of light metals. PM aluminium alloys with improved properties are on the way to replace ferrous pars. For high temperature applications in the engine, titanium aluminide based materials offer a great potential, e.g. for exhaust valves. The PM route using elemental powders and reactions sintering is considered to be a cost effective way for net shape parts production. Furthermore it is expected that lower costs for titanium raw materials coming from metallurgical activities will offer new chances for sintered parts with titanium alloys. The field of cellular metals expands with the hollow sphere technique, that can provide materials of many metals and alloys with a great flexibility in structure modifications. These structures are expected to be used in improving the safety (crash absoption) and noise reduction in cars in the near future and offer great potential for many other applications.