According to the star formation rate and metal enrichment rate given by the disk-halo model of Lee and Ann (1981), the two different forms of time-dependent initial mass function (IMF) and the present day mass function (PDMF) of nearby stars have been examined. It was shown that the constraint for the initial rapid metal enrichment requires the time-dependence of IMF at the very early phase ( t ≲ 5 × 10 8 yrs) of the solar neighborhood. The computed PDMF's show that the PDMF is nearly independent of any specific functional form of IMF as long as the latter includes a Gaussian distribution of log m. This result is due to the very small fractional mass ( × 5 of stars formed at the very early period during which the IMF is time-dependent. The computed PDMF suggests the presence of more numerous low mass stars than shown in Miller and Scalo's (1979) PDMF, supporting the possibility of the existence of low-velocity M dwarfs. According to the number distribution of stars with respect to [Fe/H], the mean age of these low mass star must be very old so as to yield the mean metal abundance ¯ [ F e / H ] ≈ − 0.15 for the stars in the solar neighborhood.

Weibull analyses given to the initial mass function (IMF) deduced by Miller and Scalo (1979) have shown that the mass dependence of IMF is an exp [ − α m ] - form in low mass range while in the high mass range it assumes an exp [ − α √ m ] / √ m -form with the break-up being at about the solar mass. Various astrophysical reasonings are given for identifying the exp [ − α m ] and exp [ − α √ m ] / √ m with halo and disk star characteristics, respectively. The physical conditions during the halo formation were such that low mass stars were preferentially formed and those in the disk high mass stars favoured. The two component nature of IMF is in general accord with the dichotomies in various stellar properties.

The evolutionary tracks of a protostar of one solar mass under quasi-hydrostatic equilibrium are computed with mass-accretion time scales of 10^3,10^4,10^5 and 10^6 years, and their resulting behaviors in the H-R diagram are discussed. It is found that there exists a critical time scale of mass accretion, which reverses the course of their evolutionary tracks. A value of the critical time scale appears to lie between 10^3 and 10^4 years. The physical cause for the presence of the critical time scale is discussed. Finally, it is proposed that star formation requires at least several 10^3 years before any star is born out of dark dense interstellar clouds.

We have collected times of minimum light available in the literature for WZ Andromedae and analyzed the nature of the period variations. The O-C diagram of WZ And clearly shows that two abrupt changes near JD 2418000 and JD 2435000 are deduced by dp/p= + 4.24 |timesa 10 − 6 and dp/p= − 2.46 × 10 − 6 , respectively. For these period changes, we have introduced the equations which represent mass exchange in the close binery systems given by Biermann and Hall (1973), and the computation yieleled a mass flow of 7.42 × 10 − 5 M . from the hotter component to the cooler one. Due to the amount of mass flow, the period decrease may also be calculated. The theoritical new period after JD 2435000 became 0.69565858 days, which is in good agreement with the value 0.69566034 days found in the O-C diagram. In this computation, the mass ratio of WZ And suggested that the hotter star is the filling its Rochclooe, and thus WZ And is in Paczynski's stage II.

Densities of the three constituent spheroids of the same eccentricity as our earlier model of the Galaxy are assumed to be given by an analytical form of ρ i (r)= k i e − m i r u i , where k i , m i , and α i are obtained by comparing with the results of the previous model. Using three values of ρ i (r) the galactic rotation curve, mass of each spheroid and the whole Galaxy are calculated, and the three dimensional density distribution in the Galaxy is also obtained. The calculated rotation curve of the model Galaxy is in good agreement with the observed curve, and the shape of the cross section of the model Galaxy given by the computed density is very similar to the inferred shape of the spiral galaxies.

An improved version of the galatic mass distribution has been derived by increasing the number of shells in each spheroid of our earlier model. It is found that the increase of the number of the shell improves the model considerably, thus making it agree far better with observations.

A simple model of the galactic mass distribution consisting of one sphere and two spheroids with different eccentricities is considered. The resulting model is found to be consistent with the recent observations of the galactic rotation as well as suggested shape of the Galaxy.

1. 침파리의 동계사육 결과 평균온도 에서 유충기간 7일, 용기간 9.2일, 전산란기간 14.2일, 성충수명 23.3일이었다. 2. 5월부터 7월까지 사육온도 로 고정시켰을 때의 생육기간은 유충기간 8.0일, 용기간 5.3일, 전산란기간 11.7일, 성충수명 30.1일 이었다. 3. 용 개체중량은 5월-7월의 에서 13.3mg으로서 현저한 증가를 볼 수 있었다. 4. 전산란 기간중의 성충사망율은 습도 조절(R. H.)에 따라서 큰 차이를 보여주었으며 누대사육을위해서는 의 R.H.를 유지할 필요가 있을 것으로 본다. 5. 성충의 산란율은 산란 시작후 제8-10일에 제일 높다.

갈색엽고병(Fusarium niwate)의 효과적인 접종방법을 찾아내기 위해 본 시험을 수행하였던 바 다음과 같은 결과를 얻었다. 1) 본 균의 분생포자의 증류수 현탁액을 벼 유묘에 분무접종할 때, 접종 후 습실에 1일 보존했을 경우에는 거의 발병이 되지 않았으나 2일간 보존한 겅우에는 어느 정도 병반이 나타났다. 2) 벼 유묘에 바람이나 또는 나무막대기로 물리적인 상처를 입힌 다음 증류수 포자현탁액을 분무한 결과 상당한 병만이 형성되었다. 3) 포자현탁액에 벼 잎 추출액, glucose, polypeptone, yeast exract 등의 용액을 첨가 분무접종했을 때 병반형성이 양호하였다. 4) 포자발아상태는 종류수중에서는 불량하였으나 영양분을 첨가한 용액중에서는 발아력도 좋았고 균사의 융합도 양호하게 일어났다. 5) 본 접종시험의 결과 통일품종은 재래 장려품종인 풍광에 비해 본 병에 대해 약했다.

환성진화(桓星進化)의 최종단계(最終段階)에서 이루어지는 고밀도성(高密度星)(백색왜성(白色矮星), 중성자성(中性子星))의 평형(平衡)의 한계질량(限界質量)은 현재(現在)까지 태양질량(太陽質量)의 0.6 ∼ 2 배(倍)로 알려졌다. 이 값의 차이(差異)는 가정(假定)한 상태방정식(狀態方程式)에 따르고 있으나 그 어느것이나 모두 태양(太陽)의 질량(質量)과 대차(大差)없다는 사실(事實)은 주목(注目)할 일이다. 또 관측(觀測)된 보통(普通)의 별의 질량(質量)도 태양질량(太陽質量)의 1 10 ∼ 60 배(倍)의 범위에 있다. 이 두 사실(事實)을 종합(綜合)하여 태양(太陽)의 질량(質量)이 가지는 특정(特定)한 자리의 물리적(物理的)인 근거(根據)로서 Polytrope 기체(氣體)의 지수(指數) ( γ = 4 3 ) 와 ( ℏ c G m H 2 ) 3 2 의 지수(指數)사이의 연관성(聯關性)을 고찰(考察)하였다.

Chelating agents in low and intermediate radioactive wastes can form complexes with radionuclides and increase the mobility of the radionuclides. According to the Korea Radioactive Waste Agency (Acceptance criteria for low and intermediate radioactive waste, WAC-SIL-2022-1), if the amount of residual chelating agents in the waste are greater than 0.1%, the chemical names and residual amounts should be specified; if greater than 1%, the waste must be solidified and contain no more than 8%. The existing method for analyzing chelates in radioactive waste was based on UV–Visible spectrophotometry (UV-Vis), but the new method is based on liquid chromatography/mass spectrometry (LC-MS). The analysis was performed in aqueous solution before applying to real samples. Since the real sample may contain several heavy metals, it is expected that the chelates will exist as complexes. Therefore, 1.0×10-4 mol L-1 of EDTA (Ethylenediaminetetraacetic acid), DTPA (Diethylenetriaminepentaacetic acid), NTA (Nitrilotriacetic acid), and excess metals in aqueous solution were analyzed using HPLC using RP (Reverse Phase) column and HILIC (Hydrophilic interaction) column. When the RP column was used, each substance eluted without separation at the beginning of the analysis. However, when analyzed using a HILIC column, the peaks of each substance were separated. LC-MS measurements using HILIC conditions resulted in separations with better sensitivity.

For the sake of future generations, the management of radioactive waste is essential. The disposal of spent nuclear fuel (SNF) is considered an urgent challenge to ensure human safety by storing it until its radioactivity drops to a negligible level. Evaluating the safety of disposal facilities is crucial to guarantee their durability for more than 100,000 years, a period sufficient for SNF radioactivity to become ignored. Past studies have proposed various parameters for forecasting the safety of SNF disposal. Among these, radiochemistry and electrochemistry play pivotal roles in predicting the corrosion-related chemical reactions occurring within the SNF and the structural materials of disposal facilities. Our study considers an extreme scenario where the SNF canister becomes compromised, allowing underground water to infiltrate and contact the SNF. We aim to improve the corrosion mechanism and mass-balance equation compared with what Shoesmith et al. proved under the same circumstances. To enhance the comprehensibility of the chemical reactions occurring within the breached SNF canister, we have organized these reactions into eight categories: mass diffusion, alpha radiolysis, adsorption, hydrate formation, solidification, decomposition, ionization, and oxidation. After categorization, we define how each species interacts with others and calculate the rate of change in species’ concentrations resulting from these reactions. By summing up the concentration change rates of each species due to these reactions, we redefine the mass-balance equations for each species. These newly categorized equations, which have not been explained in detail previously, offer a detailed description of corrosion reactions. This comprehensive understanding allows us to evaluate the safety implications of a compromised SNF canister and the associated disposal facilities by numerically solving the mass-balance equations.

Nuclear power generation is expected to be enlarged for domestic electricity supply based on the 10th Basic Plan of Long-Term Electricity Supply and Demand. However, the issues on the disposal of spent nuclear fuel or high-level radioactive waste has not been solved. KBS-3 concept of the deep geological disposal and pyroprocessing has been investigated as options for disposal and treatment way of spent nuclear fuel. In other way, the radionuclide management process with 6 scenarios are devised combining chlorination treatment and alternative disposal methods for the efficient disposal of spent nuclear fuel. Various scenarios will be considered and comprehensively optimized by evaluation on many aspects, such as waste quantity, radiotoxicity, economy and so on. Level 0 to 4 were identified with the specialized nuclide groups: Level 0 (NFBC, Hull), Level 1 (Long-lived, volatile nuclides), Level 2 (High heat emitting nuclides), Level 3 (TRU/RE), Level 4 (U). The 6 options (Op.1 to 6) were proposed with the differences between scenarios, for examples, phase types of wastes, the isolated nuclide groups, chlorination process sequences. Op.1 adopts Level 0 and 1 to separate I, Tc, Se, C, Cs nuclides which are major concerns for long-term disposal through heat treatment. The rest of spent nuclear fuel will be disposed as oxide form itself. Op.2 contains Sr separation process using chlorination by MgCl2 and precipitation by K2CO3to alleviate the burden of heat after heat treatment process. U/TRU/RE will be remained and disposed in oxide form. Op.3 is set to pyroprocessing as reference method, but residual TRU/RE chlroides after electrorefining will be recovered as precipitates by K3PO4. Op.4 introduces NH4Cl to chlorinate TRU/RE from oxides after Op.2 applied and precipitates them. TRU/RE/Sr will be simultaneously chlorinated by NH4Cl without MgCl2 in Op.5. Then, chlorinated Sr and TRU/RE groups will be separated by post-chlorination process for disposal. But, chlorinated Sr and TRU/RE are designed not to be divided in disposal steps in Op.6. In this study, the mass flow analysis of radionuclide management process scenarios with updated process variables are performed. The amount and composition of wastes by types will be addressed in detail.

Some consumer goods containing radioactive substances are in circulation and used in everyday life. In accordance with the Nuclear Safety Act, consumer goods with radioactivity are regulated. However, since most consumer goods distributed in Korea have no information that can confirm the amount of radiation, it is necessary to analyze the radiation for safety regulation. Among these consumer goods, GTLS (Gaseous Tritium Light Source) contains gaseous tritium (tritium, written as 3H or T), which is a radioactive material. The gaseous composition ratio in GTLS was analyzed using a precision gas mass spectrometer (Thermo Fisher, model MAT 271). As a result of GTLS analysis, the H2, HD or H3 +(T) or 3He, HT or D2 or He, DT, and T2, which correspond to the mass-to-charge ratio (m/z) 2 to 6 and the air components were detected. In addition, substances corresponding to m/z=24 and m/z=21 were also detected. These were compared with pure CH4 and those fragmentation patterns. The ratios of CT4 (m/z = 24) to CT3 (m/z = 21) and CH4 (m/z = 16) to CH3 (m/z = 15) were compared and they agree within the measurement uncertainty. We also performed additional experiments to separate the water component in the GTLS samples, considering the possibility that the m/z = 21 to m/z = 24 region is tritium compounds based on H2O. Despite the removal of the water components, peaks were detected at m/z=21 and m/z=24. Therefore, we confirmed that the component of m/z = 24 in the GTLS sample was CT4.